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This library enables you to use Interrupt from Hardware Timers on an NRF52-based board using mbed-RTOS such as Nano-33-BLE. These nRF52 Hardware Timers, using Interrupt, still work even if other functions are blocking. Moreover, they are much more precise (certainly depending on clock frequency accuracy) than other software timers using millis() or micros(). That's mandatory if you need to measure some data requiring better accuracy. It now supports 16 ISR-based Timers, while consuming only 1 Hardware Timer. Timers' interval is very long (ulong millisecs). The most important feature is they're ISR-based Timers. Therefore, their executions are not blocked by bad-behaving functions or tasks. This important feature is absolutely necessary for mission-critical tasks.

License: MIT License

C++ 94.01% C 5.94% Shell 0.05%
hardware-timers isr timerinterrupt-libraries arduino-libraries non-blocking mission-critical timerinterrupt timerinterrupt-library mbed accuracy

nrf52_mbed_timerinterrupt's Introduction

NRF52_MBED_TimerInterrupt Library

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Table of Contents

Important Change from v1.4.0

Please have a look at HOWTO Fix Multiple Definitions Linker Error

Why do we need this NRF52_MBED_TimerInterrupt library

Features

This library enables you to use Interrupt from Hardware Timers on an NRF52-based board using mbed-RTOS such as Nano-33-BLE.

As Hardware Timers are rare, and very precious assets of any board, this library now enables you to use up to 16 ISR-based Timers, while consuming only 1 Hardware Timer. Timers' interval is very long (ulong millisecs).

Now with these new 16 ISR-based timers, the maximum interval is practically unlimited (limited only by unsigned long milliseconds) while the accuracy is nearly perfect compared to software timers.

The most important feature is they're ISR-based timers. Therefore, their executions are not blocked by bad-behaving functions / tasks. This important feature is absolutely necessary for mission-critical tasks.

The ISR_Timer_Complex example will demonstrate the nearly perfect accuracy compared to software timers by printing the actual elapsed millisecs of each type of timers.

Being ISR-based timers, their executions are not blocked by bad-behaving functions / tasks, such as connecting to WiFi, Internet and Blynk services. You can also have many (up to 16) timers to use.

This non-being-blocked important feature is absolutely necessary for mission-critical tasks.

You'll see blynkTimer Software is blocked while system is connecting to WiFi / Internet / Blynk, as well as by blocking task in loop(), using delay() function as an example. The elapsed time then is very unaccurate

Why using ISR-based Hardware Timer Interrupt is better

Imagine you have a system with a mission-critical function, measuring water level and control the sump pump or doing something much more important. You normally use a software timer to poll, or even place the function in loop(). But what if another function is blocking the loop() or setup().

So your function might not be executed, and the result would be disastrous.

You'd prefer to have your function called, no matter what happening with other functions (busy loop, bug, etc.).

The correct choice is to use a Hardware Timer with Interrupt to call your function.

These hardware timers, using interrupt, still work even if other functions are blocking. Moreover, they are much more precise (certainly depending on clock frequency accuracy) than other software timers using millis() or micros(). That's necessary if you need to measure some data requiring better accuracy.

Functions using normal software timers, relying on loop() and calling millis(), won't work if the loop() or setup() is blocked by certain operation. For example, certain function is blocking while it's connecting to WiFi or some services.

The catch is your function is now part of an ISR (Interrupt Service Routine), and must be lean / mean, and follow certain rules. More to read on:

HOWTO Attach Interrupt

Important notes about NRF_TIMER_1

  • Starting from core mbed_nano core v2.0.0+, NRF_TIMER_1 stops working.
// For core mbed core 1.3.2-
// Depending on the board, you can select NRF52 Hardware Timer from NRF_TIMER_1,NRF_TIMER_3,NRF_TIMER_4 (1,3 and 4)
// If you select the already-used NRF_TIMER_0 or NRF_TIMER_2, it'll be auto modified to use NRF_TIMER_1

// For core mbed core 2.0.0-
// Depending on the board, you can select NRF52 Hardware Timer from NRF_TIMER_3,NRF_TIMER_4 (3 and 4)
// If you select the already-used NRF_TIMER_0, NRF_TIMER_1 or NRF_TIMER_2, it'll be auto modified to use NRF_TIMER_3

Currently supported Boards

  1. MBED nRF52840-based boards such as Nano_33_BLE, Nano_33_BLE_Sense, etc. using Arduino-mbed mbed_nano core
  2. Seeeduino nRF52840-based boards such as SEEED_XIAO_NRF52840 and SEEED_XIAO_NRF52840_SENSE, etc. using Seeeduino mbed core

Important Notes about ISR

  1. Inside the attached function, delay() won’t work and the value returned by millis() will not increment. Serial data received while in the function may be lost. You should declare as volatile any variables that you modify within the attached function.

  2. Typically global variables are used to pass data between an ISR and the main program. To make sure variables shared between an ISR and the main program are updated correctly, declare them as volatile.

Notes for recent 2.0.0 release of Arduino Mbed OS Boards platform

From Add mbed_nano to list of compatible architectures #3

In the recent 2.0.0 release of the Arduino Mbed OS Boards platform, the mbed architecture split into four architectures:

mbed_edge: Arduino Edge Control
mbed_nano: Nano 33 BLE and Nano RP2040 Connect
mbed_rp2040: Raspberry Pi Pico
mbed_portenta: Portenta H7

The mbed architecture should be retained for backwards support, but the new mbed_nano should also be added to avoid spurious incompatibility warnings and the library's examples being shown under the File > Examples > INCOMPATIBLE menu of the Arduino IDE when the Nano 33 BLE board is selected.

Prerequisites

  1. Arduino IDE 1.8.19+ for Arduino. GitHub release

  2. Arduino mbed_nano core 3.4.1+ for NRF52-based board using mbed-RTOS such as Nano-33-BLE if you don't use NRF_TIMER_1. GitHub release

  3. Arduino mbed core v1.3.2- for NRF52-based board using mbed-RTOS such as Nano-33-BLE if you'd like to use NRF_TIMER_1. Latest is GitHub release

  4. Seeeduino mbed core 2.7.2+ for Seeeduino nRF52840-based boards such as SEEED_XIAO_NRF52840 and SEEED_XIAO_NRF52840_SENSE

  5. To use with certain example

Installation

Use Arduino Library Manager

The best and easiest way is to use Arduino Library Manager. Search for NRF52_MBED_TimerInterrupt, then select / install the latest version. You can also use this link arduino-library-badge for more detailed instructions.

Manual Install

Another way to install is to:

  1. Navigate to NRF52_MBED_TimerInterrupt page.
  2. Download the latest release NRF52_MBED_TimerInterrupt-main.zip.
  3. Extract the zip file to NRF52_MBED_TimerInterrupt-main directory
  4. Copy whole NRF52_MBED_TimerInterrupt-main folder to Arduino libraries' directory such as ~/Arduino/libraries/.

VS Code & PlatformIO

  1. Install VS Code
  2. Install PlatformIO
  3. Install NRF52_MBED_TimerInterrupt library by using Library Manager. Search for NRF52_MBED_TimerInterrupt in Platform.io Author's Libraries
  4. Use included platformio.ini file from examples to ensure that all dependent libraries will installed automatically. Please visit documentation for the other options and examples at Project Configuration File

Libraries' Patches

Notes: These patches are totally optional and necessary only when you use the related Ethernet library and get certain error or issues.

1. For application requiring 2K+ HTML page

If your application requires 2K+ HTML page, the current Ethernet library must be modified if you are using W5200/W5500 Ethernet shields. W5100 is not supported for 2K+ buffer. If you use boards requiring different CS/SS pin for W5x00 Ethernet shield, for example ESP32, ESP8266, nRF52, etc., you also have to modify the following libraries to be able to specify the CS/SS pin correctly.

2. For Ethernet library

To fix Ethernet library, just copy these following files into the Ethernet library directory to overwrite the old files:

3. For EthernetLarge library

To fix EthernetLarge library, just copy these following files into the EthernetLarge library directory to overwrite the old files:

4. For Ethernet2 library

To fix Ethernet2 library, just copy these following files into the Ethernet2 library directory to overwrite the old files:

To add UDP Multicast support, necessary for the UPnP_Generic library:

5. For Ethernet3 library

  1. To fix Ethernet3 library, just copy these following files into the Ethernet3 library directory to overwrite the old files:

6. For UIPEthernet library

To be able to compile and run on nRF52 boards with ENC28J60 using UIPEthernet library, you have to copy these following files into the UIPEthernet utility directory to overwrite the old files:

HOWTO Fix Multiple Definitions Linker Error

The current library implementation, using xyz-Impl.h instead of standard xyz.cpp, possibly creates certain Multiple Definitions Linker error in certain use cases.

You can include these .hpp files

// Can be included as many times as necessary, without `Multiple Definitions` Linker Error
#include "NRF52_MBED_TimerInterrupt.hpp"   //https://github.com/khoih-prog/NRF52_MBED_TimerInterrupt

// Can be included as many times as necessary, without `Multiple Definitions` Linker Error
#include "NRF52_MBED_ISR_Timer.hpp"        //https://github.com/khoih-prog/NRF52_MBED_TimerInterrupt

in many files. But be sure to use the following .h files in just 1 .h, .cpp or .ino file, which must not be included in any other file, to avoid Multiple Definitions Linker Error

// To be included only in main(), .ino with setup() to avoid `Multiple Definitions` Linker Error
#include "NRF52_MBED_TimerInterrupt.h"     //https://github.com/khoih-prog/NRF52_MBED_TimerInterrupt

// To be included only in main(), .ino with setup() to avoid `Multiple Definitions` Linker Error
#include "NRF52_MBED_ISR_Timer.h"          //https://github.com/khoih-prog/NRF52_MBED_TimerInterrupt

Check the new multiFileProject example for a HOWTO demo.

New from v1.0.1

Now with these new 16 ISR-based timers (while consuming only 1 hardware timer), the maximum interval is practically unlimited (limited only by unsigned long milliseconds). The accuracy is nearly perfect compared to software timers. The most important feature is they're ISR-based timers Therefore, their executions are not blocked by bad-behaving functions / tasks. This important feature is absolutely necessary for mission-critical tasks.

The ISR_16_Timers_Array example will demonstrate the nearly perfect accuracy compared to software timers by printing the actual elapsed millisecs of each type of timers. Being ISR-based timers, their executions are not blocked by bad-behaving functions / tasks, such as connecting to WiFi, Internet and Blynk services. You can also have many (up to 16) timers to use. This non-being-blocked important feature is absolutely necessary for mission-critical tasks. You'll see blynkTimer Software is blocked while system is connecting to WiFi / Internet / Blynk, as well as by blocking task in loop(), using delay() function as an example. The elapsed time then is very unaccurate

Usage

Before using any Timer, you have to make sure the Timer has not been used by any other purpose.

1. Using only Hardware Timer directly

1.1 Init Hardware Timer

// For core mbed core 1.3.2-
// Depending on the board, you can select NRF52 Hardware Timer from NRF_TIMER_1,NRF_TIMER_3,NRF_TIMER_4 (1,3 and 4)
// If you select the already-used NRF_TIMER_0 or NRF_TIMER_2, it'll be auto modified to use NRF_TIMER_1

// For core mbed core 2.0.0-
// Depending on the board, you can select NRF52 Hardware Timer from NRF_TIMER_3,NRF_TIMER_4 (3 and 4)
// If you select the already-used NRF_TIMER_0, NRF_TIMER_1 or NRF_TIMER_2, it'll be auto modified to use NRF_TIMER_3

// Init NRF52 timer NRF_TIMER3
NRF52_MBED_Timer ITimer(NRF_TIMER_3);

1.2 Set Hardware Timer Interval and attach Timer Interrupt Handler function

Use one of these functions with interval in unsigned long milliseconds

// interval (in microseconds).
// No params and duration now. To be added in the future by adding similar functions here or to NRF52-hal-timer.c
bool setInterval(unsigned long interval, timerCallback callback);

// interval (in microseconds).
// No params and duration now. To be added in the future by adding similar functions here or to NRF52-hal-timer.c
bool attachInterruptInterval(unsigned long interval, timerCallback callback);

as follows

void TimerHandler(void)
{
  // Doing something here inside ISR
  // No Serial.print() can be used
}

#define TIMER_INTERVAL_MS        1000      // 1s = 1000ms
void setup()
{
  ....
  
  // Interval in microsecs
  if (ITimer.attachInterruptInterval(TIMER_INTERVAL_MS * 1000, TimerHandler0))
  {
    Serial.print(F("Starting ITimer0 OK, millis() = ")); Serial.println(millis());
  }
  else
    Serial.println(F("Can't set ITimer0. Select another freq. or timer));
}

1.3 Set Hardware Timer Frequency and attach Timer Interrupt Handler function

Use one of these functions with frequency in float Hz

// frequency (in hertz).
// No params and duration now. To be added in the future by adding similar functions here or to NRF52-hal-timer.c
bool setFrequency(float frequency, timerCallback callback);

// frequency (in hertz).
bool attachInterrupt(float frequency, timerCallback callback);

as follows

void TimerHandler0()
{
  // Doing something here inside ISR
  // No Serial.print() can be used
}

#define TIMER0_FREQ_HZ        5555.555

void setup()
{
  ....
  
  // Frequency in float Hz
  if (ITimer0.attachInterrupt(TIMER0_FREQ_HZ, TimerHandler0))
  {
    Serial.print(F("Starting ITimer0 OK, millis() = ")); Serial.println(millis());
  }
  else
    Serial.println(F("Can't set ITimer0. Select another freq. or timer));
}

2. Using 16 ISR_based Timers from 1 Hardware Timer

2.1 Important Note

The 16 ISR_based Timers, designed for long timer intervals, only support using unsigned long millisec intervals. If you have to use much higher frequency or sub-millisecond interval, you have to use the Hardware Timers directly as in 1.3 Set Hardware Timer Frequency and attach Timer Interrupt Handler function

2.2 Init Hardware Timer and ISR-based Timer

// For core mbed core 1.3.2-
// Depending on the board, you can select NRF52 Hardware Timer from NRF_TIMER_1,NRF_TIMER_3,NRF_TIMER_4 (1,3 and 4)
// If you select the already-used NRF_TIMER_0 or NRF_TIMER_2, it'll be auto modified to use NRF_TIMER_1

// For core mbed core 2.0.0-
// Depending on the board, you can select NRF52 Hardware Timer from NRF_TIMER_3,NRF_TIMER_4 (3 and 4)
// If you select the already-used NRF_TIMER_0, NRF_TIMER_1 or NRF_TIMER_2, it'll be auto modified to use NRF_TIMER_3

// Init NRF52 timer NRF_TIMER3
NRF52_MBED_Timer ITimer(NRF_TIMER_3);

// Init NRF52_MBED_ISRTimer
// Each NRF52_MBED_ISRTimer can service 16 different ISR-based timers
NRF52_MBED_ISRTimer ISR_Timer;

2.3 Set Hardware Timer Interval and attach Timer Interrupt Handler functions

void TimerHandler(void)
{
  ISR_Timer.run();
}

#define HW_TIMER_INTERVAL_MS          50L

#define TIMER_INTERVAL_2S             2000L
#define TIMER_INTERVAL_5S             5000L
#define TIMER_INTERVAL_11S            11000L
#define TIMER_INTERVAL_101S           101000L

// In NRF52, avoid doing something fancy in ISR, for example complex Serial.print with String() argument
// The pure simple Serial.prints here are just for demonstration and testing. Must be eliminate in working environment
// Or you can get this run-time error / crash
void doingSomething2s()
{
  // Doing something here inside ISR
}
  
void doingSomething5s()
{
  // Doing something here inside ISR
}

void doingSomething11s()
{
  // Doing something here inside ISR
}

void doingSomething101s()
{
  // Doing something here inside ISR
}

void setup()
{
  ....
  
  // Interval in microsecs
  if (ITimer.attachInterruptInterval(HW_TIMER_INTERVAL_MS * 1000, TimerHandler))
  {
    lastMillis = millis();
    Serial.printf("Starting  ITimer OK, millis() = %ld\n", lastMillis);
  }
  else
    Serial.println("Can't set ITimer correctly. Select another freq. or interval");

  // Just to demonstrate, don't use too many ISR Timers if not absolutely necessary
  // You can use up to 16 timer for each ISR_Timer
  ISR_Timer.setInterval(TIMER_INTERVAL_2S, doingSomething2s);
  ISR_Timer.setInterval(TIMER_INTERVAL_5S, doingSomething5s);
  ISR_Timer.setInterval(TIMER_INTERVAL_11S, doingSomething11s);
  ISR_Timer.setInterval(TIMER_INTERVAL_101S, doingSomething101s);
}

Examples:

  1. Argument_None
  2. ISR_16_Timers_Array
  3. ISR_16_Timers_Array_Complex
  4. SwitchDebounce
  5. TimerInterruptTest
  6. TimerInterruptLEDDemo
  7. FakeAnalogWrite
  8. Change_Interval
  9. multiFileProject New

Example ISR_16_Timers_Array_Complex

NRF52_MBED_TimerInterrupt/examples/ISR_16_Timers_Array_Complex/ISR_16_Timers_Array_Complex.ino

Lines 35 to 387 in c302b0d

#if !( ARDUINO_ARCH_NRF52840 && TARGET_NAME == ARDUINO_NANO33BLE )
#error This code is designed to run on nRF52-based Nano-33-BLE boards using mbed-RTOS platform! Please check your Tools->Board setting.
#endif
// These define's must be placed at the beginning before #include "NRF52TimerInterrupt.h"
// _TIMERINTERRUPT_LOGLEVEL_ from 0 to 4
// Don't define _TIMERINTERRUPT_LOGLEVEL_ > 0. Only for special ISR debugging only. Can hang the system.
// For Nano33-BLE, don't use Serial.print() in ISR as system will definitely hang.
#define TIMER_INTERRUPT_DEBUG 0
#define _TIMERINTERRUPT_LOGLEVEL_ 3
// To be included only in main(), .ino with setup() to avoid `Multiple Definitions` Linker Error
#include "NRF52_MBED_TimerInterrupt.h"
// To be included only in main(), .ino with setup() to avoid `Multiple Definitions` Linker Error
#include "NRF52_MBED_ISR_Timer.h"
#include <SimpleTimer.h> // https://github.com/jfturcot/SimpleTimer
#ifndef LED_BUILTIN
#define LED_BUILTIN D13
#endif
#ifndef LED_BLUE_PIN
#if defined(LEDB)
#define LED_BLUE_PIN LEDB
#else
#define LED_BLUE_PIN D7
#endif
#endif
#ifndef LED_RED_PIN
#if defined(LEDR)
#define LED_RED_PIN LEDR
#else
#define LED_RED_PIN D8
#endif
#endif
#define HW_TIMER_INTERVAL_US 10000L
volatile uint32_t startMillis = 0;
// For core mbed core 1.3.2-
// Depending on the board, you can select NRF52 Hardware Timer from NRF_TIMER_1,NRF_TIMER_3,NRF_TIMER_4 (1,3 and 4)
// If you select the already-used NRF_TIMER_0 or NRF_TIMER_2, it'll be auto modified to use NRF_TIMER_1
// For core mbed core 2.0.0-
// Depending on the board, you can select NRF52 Hardware Timer from NRF_TIMER_3,NRF_TIMER_4 (3 and 4)
// If you select the already-used NRF_TIMER_0, NRF_TIMER_1 or NRF_TIMER_2, it'll be auto modified to use NRF_TIMER_3
// Init NRF52 timer NRF_TIMER3
NRF52_MBED_Timer ITimer(NRF_TIMER_3);
// Init NRF52_MBED_ISRTimer
// Each NRF52_MBED_ISRTimer can service 16 different ISR-based timers
NRF52_MBED_ISRTimer ISR_Timer;
#define LED_TOGGLE_INTERVAL_MS 2000L
void TimerHandler()
{
static bool toggle = false;
static int timeRun = 0;
ISR_Timer.run();
// Toggle LED every LED_TOGGLE_INTERVAL_MS = 2000ms = 2s
if (++timeRun == ((LED_TOGGLE_INTERVAL_MS * 1000) / HW_TIMER_INTERVAL_US) )
{
timeRun = 0;
//timer interrupt toggles pin LED_BUILTIN
digitalWrite(LED_BUILTIN, toggle);
toggle = !toggle;
}
}
/////////////////////////////////////////////////
#define NUMBER_ISR_TIMERS 16
typedef void (*irqCallback) ();
/////////////////////////////////////////////////
#define USE_COMPLEX_STRUCT true
#if USE_COMPLEX_STRUCT
typedef struct
{
irqCallback irqCallbackFunc;
uint32_t TimerInterval;
unsigned long deltaMillis;
unsigned long previousMillis;
} ISRTimerData;
// In NRF52, avoid doing something fancy in ISR, for example Serial.print()
// The pure simple Serial.prints here are just for demonstration and testing. Must be eliminate in working environment
// Or you can get this run-time error / crash
void doingSomething(int index);
#else
volatile unsigned long deltaMillis [NUMBER_ISR_TIMERS] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
volatile unsigned long previousMillis [NUMBER_ISR_TIMERS] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
// You can assign any interval for any timer here, in milliseconds
uint32_t TimerInterval[NUMBER_ISR_TIMERS] =
{
5000L, 10000L, 15000L, 20000L, 25000L, 30000L, 35000L, 40000L,
45000L, 50000L, 55000L, 60000L, 65000L, 70000L, 75000L, 80000L
};
void doingSomething(int index)
{
unsigned long currentMillis = millis();
deltaMillis[index] = currentMillis - previousMillis[index];
previousMillis[index] = currentMillis;
}
#endif
////////////////////////////////////
// Shared
////////////////////////////////////
void doingSomething0()
{
doingSomething(0);
}
void doingSomething1()
{
doingSomething(1);
}
void doingSomething2()
{
doingSomething(2);
}
void doingSomething3()
{
doingSomething(3);
}
void doingSomething4()
{
doingSomething(4);
}
void doingSomething5()
{
doingSomething(5);
}
void doingSomething6()
{
doingSomething(6);
}
void doingSomething7()
{
doingSomething(7);
}
void doingSomething8()
{
doingSomething(8);
}
void doingSomething9()
{
doingSomething(9);
}
void doingSomething10()
{
doingSomething(10);
}
void doingSomething11()
{
doingSomething(11);
}
void doingSomething12()
{
doingSomething(12);
}
void doingSomething13()
{
doingSomething(13);
}
void doingSomething14()
{
doingSomething(14);
}
void doingSomething15()
{
doingSomething(15);
}
#if USE_COMPLEX_STRUCT
ISRTimerData curISRTimerData[NUMBER_ISR_TIMERS] =
{
//irqCallbackFunc, TimerInterval, deltaMillis, previousMillis
{ doingSomething0, 5000L, 0, 0 },
{ doingSomething1, 10000L, 0, 0 },
{ doingSomething2, 15000L, 0, 0 },
{ doingSomething3, 20000L, 0, 0 },
{ doingSomething4, 25000L, 0, 0 },
{ doingSomething5, 30000L, 0, 0 },
{ doingSomething6, 35000L, 0, 0 },
{ doingSomething7, 40000L, 0, 0 },
{ doingSomething8, 45000L, 0, 0 },
{ doingSomething9, 50000L, 0, 0 },
{ doingSomething10, 55000L, 0, 0 },
{ doingSomething11, 60000L, 0, 0 },
{ doingSomething12, 65000L, 0, 0 },
{ doingSomething13, 70000L, 0, 0 },
{ doingSomething14, 75000L, 0, 0 },
{ doingSomething15, 80000L, 0, 0 }
};
void doingSomething(int index)
{
unsigned long currentMillis = millis();
curISRTimerData[index].deltaMillis = currentMillis - curISRTimerData[index].previousMillis;
curISRTimerData[index].previousMillis = currentMillis;
}
#else
irqCallback irqCallbackFunc[NUMBER_ISR_TIMERS] =
{
doingSomething0, doingSomething1, doingSomething2, doingSomething3,
doingSomething4, doingSomething5, doingSomething6, doingSomething7,
doingSomething8, doingSomething9, doingSomething10, doingSomething11,
doingSomething12, doingSomething13, doingSomething14, doingSomething15
};
#endif
///////////////////////////////////////////
#define SIMPLE_TIMER_MS 2000L
// Init SimpleTimer
SimpleTimer simpleTimer;
// Here is software Timer, you can do somewhat fancy stuffs without many issues.
// But always avoid
// 1. Long delay() it just doing nothing and pain-without-gain wasting CPU power.Plan and design your code / strategy ahead
// 2. Very long "do", "while", "for" loops without predetermined exit time.
void simpleTimerDoingSomething2s()
{
static unsigned long previousMillis = startMillis;
unsigned long currMillis = millis();
Serial.print(F("SimpleTimer : "));
Serial.print(SIMPLE_TIMER_MS / 1000);
Serial.print(F(", ms : "));
Serial.print(currMillis);
Serial.print(F(", Dms : "));
Serial.println(currMillis - previousMillis);
for (uint16_t i = 0; i < NUMBER_ISR_TIMERS; i++)
{
#if USE_COMPLEX_STRUCT
Serial.print(F("Timer : "));
Serial.print(i);
Serial.print(F(", programmed : "));
Serial.print(curISRTimerData[i].TimerInterval);
Serial.print(F(", actual : "));
Serial.println(curISRTimerData[i].deltaMillis);
#else
Serial.print(F("Timer : "));
Serial.print(i);
Serial.print(F(", programmed : "));
Serial.print(TimerInterval[i]);
Serial.print(F(", actual : "));
Serial.println(deltaMillis[i]);
#endif
}
previousMillis = currMillis;
}
void setup()
{
pinMode(LED_BUILTIN, OUTPUT);
Serial.begin(115200);
while (!Serial && millis() < 5000);
delay(100);
Serial.print(F("\nStarting ISR_16_Timers_Array_Complex on "));
Serial.println(BOARD_NAME);
Serial.println(NRF52_MBED_TIMER_INTERRUPT_VERSION);
// Interval in microsecs
if (ITimer.attachInterruptInterval(HW_TIMER_INTERVAL_US, TimerHandler))
{
startMillis = millis();
Serial.print(F("Starting ITimer OK, millis() = "));
Serial.println(startMillis);
}
else
Serial.println(F("Can't set ITimer. Select another freq. or interval"));
// Just to demonstrate, don't use too many ISR Timers if not absolutely necessary
// You can use up to 16 timer for each ISR_Timer
for (uint16_t i = 0; i < NUMBER_ISR_TIMERS; i++)
{
#if USE_COMPLEX_STRUCT
curISRTimerData[i].previousMillis = startMillis;
ISR_Timer.setInterval(curISRTimerData[i].TimerInterval, curISRTimerData[i].irqCallbackFunc);
#else
previousMillis[i] = startMillis;
ISR_Timer.setInterval(TimerInterval[i], irqCallbackFunc[i]);
#endif
}
// You need this timer for non-critical tasks. Avoid abusing ISR if not absolutely necessary.
simpleTimer.setInterval(SIMPLE_TIMER_MS, simpleTimerDoingSomething2s);
}
#define BLOCKING_TIME_MS 3000L
void loop()
{
// This unadvised blocking task is used to demonstrate the blocking effects onto the execution and accuracy to Software timer
// You see the time elapse of ISR_Timer still accurate, whereas very unaccurate for Software Timer
// The time elapse for 2000ms software timer now becomes 3000ms (BLOCKING_TIME_MS)
// While that of ISR_Timer is still prefect.
delay(BLOCKING_TIME_MS);
// You need this Software timer for non-critical tasks. Avoid abusing ISR if not absolutely necessary
// You don't need to and never call ISR_Timer.run() here in the loop(). It's already handled by ISR timer.
simpleTimer.run();
}

Debug Terminal Output Samples

1. ISR_16_Timers_Array_Complex on Arduino Nano_33_BLE

The following is the sample terminal output when running example ISR_16_Timers_Array_Complex on Arduino Nano_33_BLE to demonstrate the accuracy of ISR Hardware Timer, especially when system is very busy. The ISR timer is programmed for 2s, is activated exactly after 2.000s !!!

While software timer, **programmed for 2s, is activated after more than 3.000s in loop().

Starting ISR_16_Timers_Array_Complex on Nano 33 BLE
NRF52_MBED_TimerInterrupt v1.4.1
[TISR] Timer = NRF_TIMER3, Timer Clock (Hz) = 1000000.00
[TISR] Frequency = 100.00, _count = 10000
Starting  ITimer OK, millis() = 714
simpleTimer2s, ms=3714, Dms=3000
Timer : 0, programmed : 5000, actual : 0
Timer : 1, programmed : 10000, actual : 0
Timer : 2, programmed : 15000, actual : 0
Timer : 3, programmed : 20000, actual : 0
Timer : 4, programmed : 25000, actual : 0
Timer : 5, programmed : 30000, actual : 0
Timer : 6, programmed : 35000, actual : 0
Timer : 7, programmed : 40000, actual : 0
Timer : 8, programmed : 45000, actual : 0
Timer : 9, programmed : 50000, actual : 0
Timer : 10, programmed : 55000, actual : 0
Timer : 11, programmed : 60000, actual : 0
Timer : 12, programmed : 65000, actual : 0
Timer : 13, programmed : 70000, actual : 0
Timer : 14, programmed : 75000, actual : 0
Timer : 15, programmed : 80000, actual : 0
simpleTimer2s, ms=6730, Dms=3016
Timer : 0, programmed : 5000, actual : 5004
Timer : 1, programmed : 10000, actual : 0
Timer : 2, programmed : 15000, actual : 0
Timer : 3, programmed : 20000, actual : 0
Timer : 4, programmed : 25000, actual : 0
Timer : 5, programmed : 30000, actual : 0
Timer : 6, programmed : 35000, actual : 0
Timer : 7, programmed : 40000, actual : 0
Timer : 8, programmed : 45000, actual : 0
Timer : 9, programmed : 50000, actual : 0
Timer : 10, programmed : 55000, actual : 0
Timer : 11, programmed : 60000, actual : 0
Timer : 12, programmed : 65000, actual : 0
Timer : 13, programmed : 70000, actual : 0
Timer : 14, programmed : 75000, actual : 0
Timer : 15, programmed : 80000, actual : 0
simpleTimer2s, ms=9746, Dms=3016
Timer : 0, programmed : 5000, actual : 5004
Timer : 1, programmed : 10000, actual : 0
Timer : 2, programmed : 15000, actual : 0
Timer : 3, programmed : 20000, actual : 0
Timer : 4, programmed : 25000, actual : 0
Timer : 5, programmed : 30000, actual : 0
Timer : 6, programmed : 35000, actual : 0
Timer : 7, programmed : 40000, actual : 0
Timer : 8, programmed : 45000, actual : 0
Timer : 9, programmed : 50000, actual : 0
Timer : 10, programmed : 55000, actual : 0
Timer : 11, programmed : 60000, actual : 0
Timer : 12, programmed : 65000, actual : 0
Timer : 13, programmed : 70000, actual : 0
Timer : 14, programmed : 75000, actual : 0
Timer : 15, programmed : 80000, actual : 0
simpleTimer2s, ms=12762, Dms=3016
Timer : 0, programmed : 5000, actual : 5004
Timer : 1, programmed : 10000, actual : 10008
Timer : 2, programmed : 15000, actual : 0
Timer : 3, programmed : 20000, actual : 0
Timer : 4, programmed : 25000, actual : 0
Timer : 5, programmed : 30000, actual : 0
Timer : 6, programmed : 35000, actual : 0
Timer : 7, programmed : 40000, actual : 0
Timer : 8, programmed : 45000, actual : 0
Timer : 9, programmed : 50000, actual : 0
Timer : 10, programmed : 55000, actual : 0
Timer : 11, programmed : 60000, actual : 0
Timer : 12, programmed : 65000, actual : 0
Timer : 13, programmed : 70000, actual : 0
Timer : 14, programmed : 75000, actual : 0
Timer : 15, programmed : 80000, actual : 0
simpleTimer2s, ms=15778, Dms=3016
Timer : 0, programmed : 5000, actual : 4994
Timer : 1, programmed : 10000, actual : 10008
Timer : 2, programmed : 15000, actual : 15002
Timer : 3, programmed : 20000, actual : 0
Timer : 4, programmed : 25000, actual : 0
Timer : 5, programmed : 30000, actual : 0
Timer : 6, programmed : 35000, actual : 0
Timer : 7, programmed : 40000, actual : 0
Timer : 8, programmed : 45000, actual : 0
Timer : 9, programmed : 50000, actual : 0
Timer : 10, programmed : 55000, actual : 0
Timer : 11, programmed : 60000, actual : 0
Timer : 12, programmed : 65000, actual : 0
Timer : 13, programmed : 70000, actual : 0
Timer : 14, programmed : 75000, actual : 0
Timer : 15, programmed : 80000, actual : 0
simpleTimer2s, ms=18794, Dms=3016
Timer : 0, programmed : 5000, actual : 4994
Timer : 1, programmed : 10000, actual : 10008
Timer : 2, programmed : 15000, actual : 15002
Timer : 3, programmed : 20000, actual : 0
Timer : 4, programmed : 25000, actual : 0
Timer : 5, programmed : 30000, actual : 0
Timer : 6, programmed : 35000, actual : 0
Timer : 7, programmed : 40000, actual : 0
Timer : 8, programmed : 45000, actual : 0
Timer : 9, programmed : 50000, actual : 0
Timer : 10, programmed : 55000, actual : 0
Timer : 11, programmed : 60000, actual : 0
Timer : 12, programmed : 65000, actual : 0
Timer : 13, programmed : 70000, actual : 0
Timer : 14, programmed : 75000, actual : 0
Timer : 15, programmed : 80000, actual : 0
simpleTimer2s, ms=21810, Dms=3016
Timer : 0, programmed : 5000, actual : 5002
Timer : 1, programmed : 10000, actual : 9996
Timer : 2, programmed : 15000, actual : 15002
Timer : 3, programmed : 20000, actual : 20004
Timer : 4, programmed : 25000, actual : 0
Timer : 5, programmed : 30000, actual : 0
Timer : 6, programmed : 35000, actual : 0
Timer : 7, programmed : 40000, actual : 0
Timer : 8, programmed : 45000, actual : 0
Timer : 9, programmed : 50000, actual : 0
Timer : 10, programmed : 55000, actual : 0
Timer : 11, programmed : 60000, actual : 0
Timer : 12, programmed : 65000, actual : 0
Timer : 13, programmed : 70000, actual : 0
Timer : 14, programmed : 75000, actual : 0
Timer : 15, programmed : 80000, actual : 0
simpleTimer2s, ms=24826, Dms=3016
Timer : 0, programmed : 5000, actual : 5002
Timer : 1, programmed : 10000, actual : 9996
Timer : 2, programmed : 15000, actual : 15002
Timer : 3, programmed : 20000, actual : 20004
Timer : 4, programmed : 25000, actual : 0
Timer : 5, programmed : 30000, actual : 0
Timer : 6, programmed : 35000, actual : 0
Timer : 7, programmed : 40000, actual : 0
Timer : 8, programmed : 45000, actual : 0
Timer : 9, programmed : 50000, actual : 0
Timer : 10, programmed : 55000, actual : 0
Timer : 11, programmed : 60000, actual : 0
Timer : 12, programmed : 65000, actual : 0
Timer : 13, programmed : 70000, actual : 0
Timer : 14, programmed : 75000, actual : 0
Timer : 15, programmed : 80000, actual : 0
simpleTimer2s, ms=27842, Dms=3016
Timer : 0, programmed : 5000, actual : 5002
Timer : 1, programmed : 10000, actual : 9996
Timer : 2, programmed : 15000, actual : 15002
Timer : 3, programmed : 20000, actual : 20004
Timer : 4, programmed : 25000, actual : 25006
Timer : 5, programmed : 30000, actual : 0
Timer : 6, programmed : 35000, actual : 0
Timer : 7, programmed : 40000, actual : 0
Timer : 8, programmed : 45000, actual : 0
Timer : 9, programmed : 50000, actual : 0
Timer : 10, programmed : 55000, actual : 0
Timer : 11, programmed : 60000, actual : 0
Timer : 12, programmed : 65000, actual : 0
Timer : 13, programmed : 70000, actual : 0
Timer : 14, programmed : 75000, actual : 0
Timer : 15, programmed : 80000, actual : 0
simpleTimer2s, ms=30858, Dms=3016
Timer : 0, programmed : 5000, actual : 5002
Timer : 1, programmed : 10000, actual : 10004
Timer : 2, programmed : 15000, actual : 15006
Timer : 3, programmed : 20000, actual : 20004
Timer : 4, programmed : 25000, actual : 25006
Timer : 5, programmed : 30000, actual : 30008
Timer : 6, programmed : 35000, actual : 0
Timer : 7, programmed : 40000, actual : 0
Timer : 8, programmed : 45000, actual : 0
Timer : 9, programmed : 50000, actual : 0
Timer : 10, programmed : 55000, actual : 0
Timer : 11, programmed : 60000, actual : 0
Timer : 12, programmed : 65000, actual : 0
Timer : 13, programmed : 70000, actual : 0
Timer : 14, programmed : 75000, actual : 0
Timer : 15, programmed : 80000, actual : 0
simpleTimer2s, ms=33874, Dms=3016
Timer : 0, programmed : 5000, actual : 5002
Timer : 1, programmed : 10000, actual : 10004
Timer : 2, programmed : 15000, actual : 15006
Timer : 3, programmed : 20000, actual : 20004
Timer : 4, programmed : 25000, actual : 25006
Timer : 5, programmed : 30000, actual : 30008
Timer : 6, programmed : 35000, actual : 0
Timer : 7, programmed : 40000, actual : 0
Timer : 8, programmed : 45000, actual : 0
Timer : 9, programmed : 50000, actual : 0
Timer : 10, programmed : 55000, actual : 0
Timer : 11, programmed : 60000, actual : 0
Timer : 12, programmed : 65000, actual : 0
Timer : 13, programmed : 70000, actual : 0
Timer : 14, programmed : 75000, actual : 0
Timer : 15, programmed : 80000, actual : 0
simpleTimer2s, ms=36890, Dms=3016
Timer : 0, programmed : 5000, actual : 4992
Timer : 1, programmed : 10000, actual : 10004
Timer : 2, programmed : 15000, actual : 15006
Timer : 3, programmed : 20000, actual : 20004
Timer : 4, programmed : 25000, actual : 25006
Timer : 5, programmed : 30000, actual : 30008
Timer : 6, programmed : 35000, actual : 35000
Timer : 7, programmed : 40000, actual : 0
Timer : 8, programmed : 45000, actual : 0
Timer : 9, programmed : 50000, actual : 0
Timer : 10, programmed : 55000, actual : 0
Timer : 11, programmed : 60000, actual : 0
Timer : 12, programmed : 65000, actual : 0
Timer : 13, programmed : 70000, actual : 0
Timer : 14, programmed : 75000, actual : 0
Timer : 15, programmed : 80000, actual : 0
simpleTimer2s, ms=39906, Dms=3016
Timer : 0, programmed : 5000, actual : 4992
Timer : 1, programmed : 10000, actual : 10004
Timer : 2, programmed : 15000, actual : 15006
Timer : 3, programmed : 20000, actual : 20004
Timer : 4, programmed : 25000, actual : 25006
Timer : 5, programmed : 30000, actual : 30008
Timer : 6, programmed : 35000, actual : 35000
Timer : 7, programmed : 40000, actual : 0
Timer : 8, programmed : 45000, actual : 0
Timer : 9, programmed : 50000, actual : 0
Timer : 10, programmed : 55000, actual : 0
Timer : 11, programmed : 60000, actual : 0
Timer : 12, programmed : 65000, actual : 0
Timer : 13, programmed : 70000, actual : 0
Timer : 14, programmed : 75000, actual : 0
Timer : 15, programmed : 80000, actual : 0
simpleTimer2s, ms=42922, Dms=3016
Timer : 0, programmed : 5000, actual : 5001
Timer : 1, programmed : 10000, actual : 9993
Timer : 2, programmed : 15000, actual : 15006
Timer : 3, programmed : 20000, actual : 19997
Timer : 4, programmed : 25000, actual : 25006
Timer : 5, programmed : 30000, actual : 30008
Timer : 6, programmed : 35000, actual : 35000
Timer : 7, programmed : 40000, actual : 40001
Timer : 8, programmed : 45000, actual : 0
Timer : 9, programmed : 50000, actual : 0
Timer : 10, programmed : 55000, actual : 0
Timer : 11, programmed : 60000, actual : 0
Timer : 12, programmed : 65000, actual : 0
Timer : 13, programmed : 70000, actual : 0
Timer : 14, programmed : 75000, actual : 0
Timer : 15, programmed : 80000, actual : 0
simpleTimer2s, ms=45938, Dms=3016
Timer : 0, programmed : 5000, actual : 5001
Timer : 1, programmed : 10000, actual : 9993
Timer : 2, programmed : 15000, actual : 14994
Timer : 3, programmed : 20000, actual : 19997
Timer : 4, programmed : 25000, actual : 25006
Timer : 5, programmed : 30000, actual : 30008
Timer : 6, programmed : 35000, actual : 35000
Timer : 7, programmed : 40000, actual : 40001
Timer : 8, programmed : 45000, actual : 45002
Timer : 9, programmed : 50000, actual : 0
Timer : 10, programmed : 55000, actual : 0
Timer : 11, programmed : 60000, actual : 0
Timer : 12, programmed : 65000, actual : 0
Timer : 13, programmed : 70000, actual : 0
Timer : 14, programmed : 75000, actual : 0
Timer : 15, programmed : 80000, actual : 0
simpleTimer2s, ms=48954, Dms=3016
Timer : 0, programmed : 5000, actual : 5001
Timer : 1, programmed : 10000, actual : 9993
Timer : 2, programmed : 15000, actual : 14994
Timer : 3, programmed : 20000, actual : 19997
Timer : 4, programmed : 25000, actual : 25006
Timer : 5, programmed : 30000, actual : 30008
Timer : 6, programmed : 35000, actual : 35000
Timer : 7, programmed : 40000, actual : 40001
Timer : 8, programmed : 45000, actual : 45002
Timer : 9, programmed : 50000, actual : 0
Timer : 10, programmed : 55000, actual : 0
Timer : 11, programmed : 60000, actual : 0
Timer : 12, programmed : 65000, actual : 0
Timer : 13, programmed : 70000, actual : 0
Timer : 14, programmed : 75000, actual : 0
Timer : 15, programmed : 80000, actual : 0
simpleTimer2s, ms=51970, Dms=3016
Timer : 0, programmed : 5000, actual : 5001
Timer : 1, programmed : 10000, actual : 10002
Timer : 2, programmed : 15000, actual : 14994
Timer : 3, programmed : 20000, actual : 19997
Timer : 4, programmed : 25000, actual : 24997
Timer : 5, programmed : 30000, actual : 30008
Timer : 6, programmed : 35000, actual : 35000
Timer : 7, programmed : 40000, actual : 40001
Timer : 8, programmed : 45000, actual : 45002
Timer : 9, programmed : 50000, actual : 50003
Timer : 10, programmed : 55000, actual : 0
Timer : 11, programmed : 60000, actual : 0
Timer : 12, programmed : 65000, actual : 0
Timer : 13, programmed : 70000, actual : 0
Timer : 14, programmed : 75000, actual : 0
Timer : 15, programmed : 80000, actual : 0
simpleTimer2s, ms=54986, Dms=3016
Timer : 0, programmed : 5000, actual : 5001
Timer : 1, programmed : 10000, actual : 10002
Timer : 2, programmed : 15000, actual : 14994
Timer : 3, programmed : 20000, actual : 19997
Timer : 4, programmed : 25000, actual : 24997
Timer : 5, programmed : 30000, actual : 30008
Timer : 6, programmed : 35000, actual : 35000
Timer : 7, programmed : 40000, actual : 40001
Timer : 8, programmed : 45000, actual : 45002
Timer : 9, programmed : 50000, actual : 50003
Timer : 10, programmed : 55000, actual : 0
Timer : 11, programmed : 60000, actual : 0
Timer : 12, programmed : 65000, actual : 0
Timer : 13, programmed : 70000, actual : 0
Timer : 14, programmed : 75000, actual : 0
Timer : 15, programmed : 80000, actual : 0
simpleTimer2s, ms=58002, Dms=3016
Timer : 0, programmed : 5000, actual : 5003
Timer : 1, programmed : 10000, actual : 10002
Timer : 2, programmed : 15000, actual : 14994
Timer : 3, programmed : 20000, actual : 19997
Timer : 4, programmed : 25000, actual : 24997
Timer : 5, programmed : 30000, actual : 30008
Timer : 6, programmed : 35000, actual : 35000
Timer : 7, programmed : 40000, actual : 40001
Timer : 8, programmed : 45000, actual : 45002
Timer : 9, programmed : 50000, actual : 50003
Timer : 10, programmed : 55000, actual : 55006
Timer : 11, programmed : 60000, actual : 0
Timer : 12, programmed : 65000, actual : 0
Timer : 13, programmed : 70000, actual : 0
Timer : 14, programmed : 75000, actual : 0
Timer : 15, programmed : 80000, actual : 0
simpleTimer2s, ms=61018, Dms=3016
Timer : 0, programmed : 5000, actual : 5003
Timer : 1, programmed : 10000, actual : 10006
Timer : 2, programmed : 15000, actual : 15007
Timer : 3, programmed : 20000, actual : 20008
Timer : 4, programmed : 25000, actual : 24997
Timer : 5, programmed : 30000, actual : 30001
Timer : 6, programmed : 35000, actual : 35000
Timer : 7, programmed : 40000, actual : 40001
Timer : 8, programmed : 45000, actual : 45002
Timer : 9, programmed : 50000, actual : 50003
Timer : 10, programmed : 55000, actual : 55006
Timer : 11, programmed : 60000, actual : 60009
Timer : 12, programmed : 65000, actual : 0
Timer : 13, programmed : 70000, actual : 0
Timer : 14, programmed : 75000, actual : 0
Timer : 15, programmed : 80000, actual : 0
simpleTimer2s, ms=64034, Dms=3016
Timer : 0, programmed : 5000, actual : 5003
Timer : 1, programmed : 10000, actual : 10006
Timer : 2, programmed : 15000, actual : 15007
Timer : 3, programmed : 20000, actual : 20008
Timer : 4, programmed : 25000, actual : 24997
Timer : 5, programmed : 30000, actual : 30001
Timer : 6, programmed : 35000, actual : 35000
Timer : 7, programmed : 40000, actual : 40001
Timer : 8, programmed : 45000, actual : 45002
Timer : 9, programmed : 50000, actual : 50003
Timer : 10, programmed : 55000, actual : 55006
Timer : 11, programmed : 60000, actual : 60009
Timer : 12, programmed : 65000, actual : 0
Timer : 13, programmed : 70000, actual : 0
Timer : 14, programmed : 75000, actual : 0
Timer : 15, programmed : 80000, actual : 0
simpleTimer2s, ms=67050, Dms=3016
Timer : 0, programmed : 5000, actual : 4992
Timer : 1, programmed : 10000, actual : 10006
Timer : 2, programmed : 15000, actual : 15007
Timer : 3, programmed : 20000, actual : 20008
Timer : 4, programmed : 25000, actual : 24997
Timer : 5, programmed : 30000, actual : 30001
Timer : 6, programmed : 35000, actual : 35000
Timer : 7, programmed : 40000, actual : 40001
Timer : 8, programmed : 45000, actual : 45002
Timer : 9, programmed : 50000, actual : 50003
Timer : 10, programmed : 55000, actual : 55006
Timer : 11, programmed : 60000, actual : 60009
Timer : 12, programmed : 65000, actual : 65001
Timer : 13, programmed : 70000, actual : 0
Timer : 14, programmed : 75000, actual : 0
Timer : 15, programmed : 80000, actual : 0
simpleTimer2s, ms=70066, Dms=3016
Timer : 0, programmed : 5000, actual : 4992
Timer : 1, programmed : 10000, actual : 10006
Timer : 2, programmed : 15000, actual : 15007
Timer : 3, programmed : 20000, actual : 20008
Timer : 4, programmed : 25000, actual : 24997
Timer : 5, programmed : 30000, actual : 30001
Timer : 6, programmed : 35000, actual : 35000
Timer : 7, programmed : 40000, actual : 40001
Timer : 8, programmed : 45000, actual : 45002
Timer : 9, programmed : 50000, actual : 50003
Timer : 10, programmed : 55000, actual : 55006
Timer : 11, programmed : 60000, actual : 60009
Timer : 12, programmed : 65000, actual : 65001
Timer : 13, programmed : 70000, actual : 0
Timer : 14, programmed : 75000, actual : 0
Timer : 15, programmed : 80000, actual : 0
simpleTimer2s, ms=73082, Dms=3016
Timer : 0, programmed : 5000, actual : 5003
Timer : 1, programmed : 10000, actual : 9995
Timer : 2, programmed : 15000, actual : 15007
Timer : 3, programmed : 20000, actual : 20008
Timer : 4, programmed : 25000, actual : 24997
Timer : 5, programmed : 30000, actual : 30001
Timer : 6, programmed : 35000, actual : 35004
Timer : 7, programmed : 40000, actual : 40001
Timer : 8, programmed : 45000, actual : 45002
Timer : 9, programmed : 50000, actual : 50003
Timer : 10, programmed : 55000, actual : 55006
Timer : 11, programmed : 60000, actual : 60009
Timer : 12, programmed : 65000, actual : 65001
Timer : 13, programmed : 70000, actual : 70004
Timer : 14, programmed : 75000, actual : 0
Timer : 15, programmed : 80000, actual : 0
simpleTimer2s, ms=76098, Dms=3016
Timer : 0, programmed : 5000, actual : 5003
Timer : 1, programmed : 10000, actual : 9995
Timer : 2, programmed : 15000, actual : 14998
Timer : 3, programmed : 20000, actual : 20008
Timer : 4, programmed : 25000, actual : 25004
Timer : 5, programmed : 30000, actual : 30001
Timer : 6, programmed : 35000, actual : 35004
Timer : 7, programmed : 40000, actual : 40001
Timer : 8, programmed : 45000, actual : 45002
Timer : 9, programmed : 50000, actual : 50003
Timer : 10, programmed : 55000, actual : 55006
Timer : 11, programmed : 60000, actual : 60009
Timer : 12, programmed : 65000, actual : 65001
Timer : 13, programmed : 70000, actual : 70004
Timer : 14, programmed : 75000, actual : 75007
Timer : 15, programmed : 80000, actual : 0
simpleTimer2s, ms=79114, Dms=3016
Timer : 0, programmed : 5000, actual : 5003
Timer : 1, programmed : 10000, actual : 9995
Timer : 2, programmed : 15000, actual : 14998
Timer : 3, programmed : 20000, actual : 20008
Timer : 4, programmed : 25000, actual : 25004
Timer : 5, programmed : 30000, actual : 30001
Timer : 6, programmed : 35000, actual : 35004
Timer : 7, programmed : 40000, actual : 40001
Timer : 8, programmed : 45000, actual : 45002
Timer : 9, programmed : 50000, actual : 50003
Timer : 10, programmed : 55000, actual : 55006
Timer : 11, programmed : 60000, actual : 60009
Timer : 12, programmed : 65000, actual : 65001
Timer : 13, programmed : 70000, actual : 70004
Timer : 14, programmed : 75000, actual : 75007
Timer : 15, programmed : 80000, actual : 0
simpleTimer2s, ms=82130, Dms=3016
Timer : 0, programmed : 5000, actual : 5002
Timer : 1, programmed : 10000, actual : 10005
Timer : 2, programmed : 15000, actual : 14998
Timer : 3, programmed : 20000, actual : 20000
Timer : 4, programmed : 25000, actual : 25004
Timer : 5, programmed : 30000, actual : 30001
Timer : 6, programmed : 35000, actual : 35004
Timer : 7, programmed : 40000, actual : 40008
Timer : 8, programmed : 45000, actual : 45002
Timer : 9, programmed : 50000, actual : 50003
Timer : 10, programmed : 55000, actual : 55006
Timer : 11, programmed : 60000, actual : 60009
Timer : 12, programmed : 65000, actual : 65001
Timer : 13, programmed : 70000, actual : 70004
Timer : 14, programmed : 75000, actual : 75007
Timer : 15, programmed : 80000, actual : 80009

2. TimerInterruptTest on Arduino Nano_33_BLE

The following is the sample terminal output when running example TimerInterruptTest on Arduino Nano_33_BLE to demonstrate the accuracy and how to start/stop Hardware Timers.

Starting TimerInterruptTest on Nano 33 BLE
NRF52_MBED_TimerInterrupt v1.4.1
[TISR] Timer = NRF_TIMER3, Timer Clock (Hz) = 1000000.00
[TISR] Frequency = 1.00, _count = 1000000
Starting ITimer0 OK, millis() = 1219
[TISR] Timer = NRF_TIMER4, Timer Clock (Hz) = 1000000.00
[TISR] Frequency = 0.33, _count = 3000000
Starting ITimer1 OK, millis() = 1221
Stop ITimer0, millis() = 5001
Start ITimer0, millis() = 10002
Stop ITimer1, millis() = 15001
Stop ITimer0, millis() = 15003
Start ITimer0, millis() = 20004
Stop ITimer0, millis() = 25005
Start ITimer1, millis() = 30002
Start ITimer0, millis() = 30006
Stop ITimer0, millis() = 35007
Start ITimer0, millis() = 40008
Stop ITimer1, millis() = 45003
Stop ITimer0, millis() = 45009

3. Argument_None on Arduino Nano_33_BLE

The following is the sample terminal output when running example Argument_None on Arduino Nano_33_BLE to demonstrate the accuracy of Hardware Timers.

Starting Argument_None on Nano 33 BLE
NRF52_MBED_TimerInterrupt v1.4.1
[TISR] Timer = NRF_TIMER4, Timer Clock (Hz) = 1000000.00
[TISR] Frequency = 2.00, _count = 500000
Starting ITimer0 OK, millis() = 814
[TISR] Timer = NRF_TIMER3, Timer Clock (Hz) = 1000000.00
[TISR] Frequency = 0.50, _count = 2000000
Starting  ITimer1 OK, millis() = 816
Time = 10001, Timer0Count = 18, Timer1Count = 4
Time = 20002, Timer0Count = 38, Timer1Count = 9
Time = 30003, Timer0Count = 58, Timer1Count = 14
Time = 40004, Timer0Count = 78, Timer1Count = 19
Time = 50005, Timer0Count = 98, Timer1Count = 24
Time = 60006, Timer0Count = 118, Timer1Count = 29

4. FakeAnalogWrite on Arduino Nano_33_BLE

The following is the sample terminal output when running example FakeAnalogWrite on Arduino Nano_33_BLE to demonstrate the usage of PWWM fakeAnalogWrite to simulate PWM analogWrite, but being able to write to many more pins.

Starting FakeAnalogWrite on Nano 33 BLE
NRF52_MBED_TimerInterrupt v1.4.1
[TISR] Timer = NRF_TIMER3, Timer Clock (Hz) = 1000000.00
[TISR] Frequency = 10000.00, _count = 100
Starting ITimer OK, millis() = 909
Add index 0, pin = 2, input PWM_Value=0, mapped PWM_Value= 0
Add index 1, pin = 3, input PWM_Value=0, mapped PWM_Value= 0
Add index 2, pin = 4, input PWM_Value=0, mapped PWM_Value= 0
Add index 3, pin = 5, input PWM_Value=0, mapped PWM_Value= 0
Add index 4, pin = 6, input PWM_Value=0, mapped PWM_Value= 0
Add index 5, pin = 7, input PWM_Value=0, mapped PWM_Value= 0
Add index 6, pin = 8, input PWM_Value=0, mapped PWM_Value= 0
Add index 7, pin = 9, input PWM_Value=0, mapped PWM_Value= 0
Test PWM_Value = 0, max = 255
Update index 0, pin = 2, input PWM_Value=5, mapped PWM_Value= 14
Update index 1, pin = 3, input PWM_Value=5, mapped PWM_Value= 14
Update index 2, pin = 4, input PWM_Value=5, mapped PWM_Value= 14
Update index 3, pin = 5, input PWM_Value=5, mapped PWM_Value= 14
Update index 4, pin = 6, input PWM_Value=5, mapped PWM_Value= 14
Update index 5, pin = 7, input PWM_Value=5, mapped PWM_Value= 14
Update index 6, pin = 8, input PWM_Value=5, mapped PWM_Value= 14
Update index 7, pin = 9, input PWM_Value=5, mapped PWM_Value= 14
Test PWM_Value = 5, max = 255
Update index 0, pin = 2, input PWM_Value=10, mapped PWM_Value= 27
Update index 1, pin = 3, input PWM_Value=10, mapped PWM_Value= 27
Update index 2, pin = 4, input PWM_Value=10, mapped PWM_Value= 27
Update index 3, pin = 5, input PWM_Value=10, mapped PWM_Value= 27
Update index 4, pin = 6, input PWM_Value=10, mapped PWM_Value= 27
Update index 5, pin = 7, input PWM_Value=10, mapped PWM_Value= 27
Update index 6, pin = 8, input PWM_Value=10, mapped PWM_Value= 27
Update index 7, pin = 9, input PWM_Value=10, mapped PWM_Value= 27
Test PWM_Value = 10, max = 255
Update index 0, pin = 2, input PWM_Value=15, mapped PWM_Value= 39
Update index 1, pin = 3, input PWM_Value=15, mapped PWM_Value= 39
Update index 2, pin = 4, input PWM_Value=15, mapped PWM_Value= 39
Update index 3, pin = 5, input PWM_Value=15, mapped PWM_Value= 39
Update index 4, pin = 6, input PWM_Value=15, mapped PWM_Value= 39
Update index 5, pin = 7, input PWM_Value=15, mapped PWM_Value= 39
Update index 6, pin = 8, input PWM_Value=15, mapped PWM_Value= 39
Update index 7, pin = 9, input PWM_Value=15, mapped PWM_Value= 39
Test PWM_Value = 15, max = 255
Update index 0, pin = 2, input PWM_Value=20, mapped PWM_Value= 49
Update index 1, pin = 3, input PWM_Value=20, mapped PWM_Value= 49
Update index 2, pin = 4, input PWM_Value=20, mapped PWM_Value= 49
Update index 3, pin = 5, input PWM_Value=20, mapped PWM_Value= 49
Update index 4, pin = 6, input PWM_Value=20, mapped PWM_Value= 49
Update index 5, pin = 7, input PWM_Value=20, mapped PWM_Value= 49
Update index 6, pin = 8, input PWM_Value=20, mapped PWM_Value= 49
Update index 7, pin = 9, input PWM_Value=20, mapped PWM_Value= 49
Test PWM_Value = 20, max = 255
...
Update index 0, pin = 2, input PWM_Value=100, mapped PWM_Value= 118
Update index 1, pin = 3, input PWM_Value=100, mapped PWM_Value= 118
Update index 2, pin = 4, input PWM_Value=100, mapped PWM_Value= 118
Update index 3, pin = 5, input PWM_Value=100, mapped PWM_Value= 118
Update index 4, pin = 6, input PWM_Value=100, mapped PWM_Value= 118
Update index 5, pin = 7, input PWM_Value=100, mapped PWM_Value= 118
Update index 6, pin = 8, input PWM_Value=100, mapped PWM_Value= 118
Update index 7, pin = 9, input PWM_Value=100, mapped PWM_Value= 118
Test PWM_Value = 100, max = 255
Update index 0, pin = 2, input PWM_Value=105, mapped PWM_Value= 120
Update index 1, pin = 3, input PWM_Value=105, mapped PWM_Value= 120
Update index 2, pin = 4, input PWM_Value=105, mapped PWM_Value= 120
Update index 3, pin = 5, input PWM_Value=105, mapped PWM_Value= 120
Update index 4, pin = 6, input PWM_Value=105, mapped PWM_Value= 120
Update index 5, pin = 7, input PWM_Value=105, mapped PWM_Value= 120
Update index 6, pin = 8, input PWM_Value=105, mapped PWM_Value= 120
Update index 7, pin = 9, input PWM_Value=105, mapped PWM_Value= 120
Test PWM_Value = 105, max = 255
Update index 0, pin = 2, input PWM_Value=110, mapped PWM_Value= 121
Update index 1, pin = 3, input PWM_Value=110, mapped PWM_Value= 121
Update index 2, pin = 4, input PWM_Value=110, mapped PWM_Value= 121
Update index 3, pin = 5, input PWM_Value=110, mapped PWM_Value= 121
Update index 4, pin = 6, input PWM_Value=110, mapped PWM_Value= 121
Update index 5, pin = 7, input PWM_Value=110, mapped PWM_Value= 121
Update index 6, pin = 8, input PWM_Value=110, mapped PWM_Value= 121
Update index 7, pin = 9, input PWM_Value=110, mapped PWM_Value= 121
Test PWM_Value = 110, max = 255
Update index 0, pin = 2, input PWM_Value=115, mapped PWM_Value= 123
Update index 1, pin = 3, input PWM_Value=115, mapped PWM_Value= 123
Update index 2, pin = 4, input PWM_Value=115, mapped PWM_Value= 123
Update index 3, pin = 5, input PWM_Value=115, mapped PWM_Value= 123
Update index 4, pin = 6, input PWM_Value=115, mapped PWM_Value= 123
Update index 5, pin = 7, input PWM_Value=115, mapped PWM_Value= 123
Update index 6, pin = 8, input PWM_Value=115, mapped PWM_Value= 123
Update index 7, pin = 9, input PWM_Value=115, mapped PWM_Value= 123
Test PWM_Value = 115, max = 255
Update index 0, pin = 2, input PWM_Value=120, mapped PWM_Value= 124
Update index 1, pin = 3, input PWM_Value=120, mapped PWM_Value= 124
Update index 2, pin = 4, input PWM_Value=120, mapped PWM_Value= 124
Update index 3, pin = 5, input PWM_Value=120, mapped PWM_Value= 124
Update index 4, pin = 6, input PWM_Value=120, mapped PWM_Value= 124
Update index 5, pin = 7, input PWM_Value=120, mapped PWM_Value= 124
Update index 6, pin = 8, input PWM_Value=120, mapped PWM_Value= 124
Update index 7, pin = 9, input PWM_Value=120, mapped PWM_Value= 124
Test PWM_Value = 120, max = 255

5. Change_Interval on Arduino Nano_33_BLE

The following is the sample terminal output when running example Change_Interval on Arduino Nano_33_BLE to demonstrate how to change Timer Interval on-the-fly

Starting Change_Interval on Nano 33 BLE
NRF52_MBED_TimerInterrupt v1.4.1
[TISR] Timer = NRF_TIMER4, Timer Clock (Hz) = 1000000.00
[TISR] Frequency = 2.00, _count = 500000
Starting ITimer0 OK, millis() = 810
[TISR] Timer = NRF_TIMER3, Timer Clock (Hz) = 1000000.00
[TISR] Frequency = 0.50, _count = 2000000
Starting ITimer1 OK, millis() = 812
Time = 10001, Timer0Count = 18, Timer1Count = 4
Time = 20002, Timer0Count = 38, Timer1Count = 9
[TISR] Timer = NRF_TIMER4, Timer Clock (Hz) = 1000000.00
[TISR] Frequency = 1.00, _count = 1000000
[TISR] Timer = NRF_TIMER3, Timer Clock (Hz) = 1000000.00
[TISR] Frequency = 0.25, _count = 4000000
Changing Interval, Timer0 = 1000,  Timer1 = 4000
Time = 30003, Timer0Count = 48, Timer1Count = 11
Time = 40004, Timer0Count = 58, Timer1Count = 14
[TISR] Timer = NRF_TIMER4, Timer Clock (Hz) = 1000000.00
[TISR] Frequency = 2.00, _count = 500000
[TISR] Timer = NRF_TIMER3, Timer Clock (Hz) = 1000000.00
[TISR] Frequency = 0.50, _count = 2000000
Changing Interval, Timer0 = 500,  Timer1 = 2000

Debug

Debug is enabled by default on Serial.

You can also change the debugging level (TIMERINTERRUPT_LOGLEVEL) from 0 to 4

// These define's must be placed at the beginning before #include "NRF52_MBED_TimerInterrupt.h"
// _TIMERINTERRUPT_LOGLEVEL_ from 0 to 4
// Don't define _TIMERINTERRUPT_LOGLEVEL_ > 0. Only for special ISR debugging only. Can hang the system.
#define TIMER_INTERRUPT_DEBUG         0
#define _TIMERINTERRUPT_LOGLEVEL_     0

Troubleshooting

If you get compilation errors, more often than not, you may need to install a newer version of the core for Arduino boards.

Sometimes, the library will only work if you update the board core to the latest version because I am using newly added functions.

Issues

Submit issues to: NRF52_MBED_TimerInterrupt issues

TO DO

  1. Search for bug and improvement.

DONE

  1. Basic hardware timers for NRF52832 and NRF52840.
  2. More hardware-initiated software-enabled timers
  3. Longer time interval
  4. Similar features for remaining Arduino boards such as AVR, ESP32, ESP8266, STM32, SAM-DUE, SAMD21/SAMD51, nRF52, Teensy, etc.
  5. Add Table of Contents
  6. Add new mbed_nano to list of compatible architectures.
  7. Fix multiple-definitions linker error
  8. Optimize library code by using reference-passing instead of value-passing
  9. Add support to Seeeduino nRF52840-based boards such as SEEED_XIAO_NRF52840 and SEEED_XIAO_NRF52840_SENSE, etc. using Seeeduino mbed core
  10. Add astyle using allman style. Restyle the library

Contributions and Thanks

Many thanks for everyone for bug reporting, new feature suggesting, testing and contributing to the development of this library.

  1. Thanks to per1234 to make PR in Add mbed_nano to list of compatible architectures #3 leading to the new version v1.2.1 to add new mbed_nano to list of compatible architectures.
  2. Thanks to cattledogGH to report issue in Nano 33 BLE will not run library examples using NRF_TIMER_1 #6 leading to the new version v1.3.0 to not use NRF_TIMER_1 because of ArduinoCore-mbed mbed_nano core v2.0.0+
per1234
per1234
 cattledogGH
cattledogGH

Contributing

If you want to contribute to this project:

  • Report bugs and errors
  • Ask for enhancements
  • Create issues and pull requests
  • Tell other people about this library

License

  • The library is licensed under MIT

Copyright

Copyright 2020- Khoi Hoang

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nrf52_mbed_timerinterrupt's Issues

Nano 33 BLE will not run library examples using NRF_TIMER_1

Arduino IDE 1.8.15
mbed nano 2.4.1 core
Board selection "Arduino Nano 33"
NRF52_MBED_TimerInterrupt v1.2.1

Library example files (e.g. Argument_None) run as expected with the use of Timer3 and Timer4. Most of the example programs are written for these two timers,

The library states

Depending on the board, you can select NRF52 Hardware Timer from NRF_TIMER_1,NRF_TIMER_3,NRF_TIMER_4 (1,3 and 4)
//If you select the already-used NRF_TIMER_0 or NRF_TIMER_2, it'll be auto modified to use NRF_TIMER_1

In library example Argument_None, if either Timer3 or Timer4 is changed to Timer1, the led will not flash and the timer count does not increment.

Is there an issue with the implementation of Timer1 on the Nano33 Ble?

/****************************************************************************************************************************
  Argument_None.ino
  For NRF52 boards using mbed-RTOS such as Nano-33-BLE
  Written by Khoi Hoang

  Built by Khoi Hoang https://github.com/khoih-prog/NRF52_MBED_TimerInterrupt
  Licensed under MIT license

  Now even you use all these new 16 ISR-based timers,with their maximum interval practically unlimited (limited only by
  unsigned long miliseconds), you just consume only one NRF52 timer and avoid conflicting with other cores' tasks.
  The accuracy is nearly perfect compared to software timers. The most important feature is they're ISR-based timers
  Therefore, their executions are not blocked by bad-behaving functions / tasks.
  This important feature is absolutely necessary for mission-critical tasks.

  Based on SimpleTimer - A timer library for Arduino.
  Author: [email protected]
  Copyright (c) 2010 OTTOTECNICA Italy

  Based on BlynkTimer.h
  Author: Volodymyr Shymanskyy

  Version: 1.2.1

  Version Modified By   Date      Comments
  ------- -----------  ---------- -----------
  1.0.1   K Hoang      22/11/2020 Initial coding and sync with NRF52_TimerInterrupt
  1.0.2   K Hoang      23/11/2020 Add and optimize examples
  1.1.1   K.Hoang      06/12/2020 Add Change_Interval example. Bump up version to sync with other TimerInterrupt Libraries
  1.2.0   K.Hoang      11/01/2021 Add better debug feature. Optimize code and examples to reduce RAM usage
  1.2.1   K.Hoang      04/05/2021 Add mbed_nano to list of compatible architectures
*****************************************************************************************************************************/

/*
   Notes:
   Special design is necessary to share data between interrupt code and the rest of your program.
   Variables usually need to be "volatile" types. Volatile tells the compiler to avoid optimizations that assume
   variable can not spontaneously change. Because your function may change variables while your program is using them,
   the compiler needs this hint. But volatile alone is often not enough.
   When accessing shared variables, usually interrupts must be disabled. Even with volatile,
   if the interrupt changes a multi-byte variable between a sequence of instructions, it can be read incorrectly.
   If your data is multiple variables, such as an array and a count, usually interrupts need to be disabled
   or the entire sequence of your code which accesses the data.
*/

#if !( ARDUINO_ARCH_NRF52840 && TARGET_NAME == ARDUINO_NANO33BLE )
  #error This code is designed to run on nRF52-based Nano-33-BLE boards using mbed-RTOS platform! Please check your Tools->Board setting.
#endif

// These define's must be placed at the beginning before #include "NRF52TimerInterrupt.h"
// _TIMERINTERRUPT_LOGLEVEL_ from 0 to 4
// Don't define _TIMERINTERRUPT_LOGLEVEL_ > 0. Only for special ISR debugging only. Can hang the system.
// For Nano33-BLE, don't use Serial.print() in ISR as system will definitely hang.
#define TIMER_INTERRUPT_DEBUG         1
#define _TIMERINTERRUPT_LOGLEVEL_     0

#include "NRF52_MBED_TimerInterrupt.h"

//#ifndef LED_BUILTIN
//  #define LED_BUILTIN         D13
//#endif

#ifndef LED_BLUE_PIN
  #define LED_BLUE_PIN          D7
#endif

#ifndef LED_RED_PIN
  #define LED_RED_PIN           D8
#endif

#define TIMER0_INTERVAL_MS        500   //1000
#define TIMER1_INTERVAL_MS        2000

volatile uint32_t Timer0Count = 0;
volatile uint32_t Timer1Count = 0;

// Depending on the board, you can select NRF52 Hardware Timer from NRF_TIMER_1,NRF_TIMER_3,NRF_TIMER_4 (1,3 and 4)
// If you select the already-used NRF_TIMER_0 or NRF_TIMER_2, it'll be auto modified to use NRF_TIMER_1

// Init NRF52 timer NRF_TIMER1
//NRF52_MBED_Timer ITimer0(NRF_TIMER_4);
NRF52_MBED_Timer ITimer0(NRF_TIMER_1);

// Init NRF52 timer NRF_TIMER3
NRF52_MBED_Timer ITimer1(NRF_TIMER_3);
//NRF52_MBED_Timer ITimer1(NRF_TIMER_1);

void printResult(uint32_t currTime)
{
  Serial.print(F("Time = ")); Serial.print(currTime); 
  Serial.print(F(", Timer0Count = ")); Serial.print(Timer0Count);
  Serial.print(F(", Timer1Count = ")); Serial.println(Timer1Count);
}

void TimerHandler0()
{
  static bool toggle0 = false;

  // Flag for checking to be sure ISR is working as SErial.print is not OK here in ISR
  Timer0Count++;

  //timer interrupt toggles pin LED_BUILTIN
  digitalWrite(LED_BUILTIN, toggle0);
  toggle0 = !toggle0;
}

void TimerHandler1()
{
  static bool toggle1 = false;

  // Flag for checking to be sure ISR is working as Serial.print is not OK here in ISR
  Timer1Count++;
  
  //timer interrupt toggles outputPin
  digitalWrite(LED_BLUE_PIN, toggle1);
  toggle1 = !toggle1;
}

void setup()
{
  pinMode(LED_BUILTIN, OUTPUT);
  pinMode(LED_BLUE_PIN, OUTPUT);
  
  Serial.begin(115200);
  while (!Serial);

  delay(100);

  Serial.print(F("\nStarting Argument_None on ")); Serial.println(BOARD_NAME);
  Serial.println(NRF52_MBED_TIMER_INTERRUPT_VERSION);
 
  // Interval in microsecs
  if (ITimer0.attachInterruptInterval(TIMER0_INTERVAL_MS * 1000, TimerHandler0))
  {
    Serial.print(F("Starting ITimer0 OK, millis() = ")); Serial.println(millis());
  }
  else
    Serial.println(F("Can't set ITimer0. Select another freq. or timer"));

  // Interval in microsecs
  if (ITimer1.attachInterruptInterval(TIMER1_INTERVAL_MS * 1000, TimerHandler1))
  {
    Serial.print(F("Starting  ITimer1 OK, millis() = ")); Serial.println(millis());
  }
  else
    Serial.println(F("Can't set ITimer1. Select another freq. or timer"));
}

#define CHECK_INTERVAL_MS     10000L

void loop()
{
  static uint32_t lastTime = 0;
  static uint32_t currTime;

  currTime = millis();

  if (currTime - lastTime > CHECK_INTERVAL_MS)
  {
    printResult(currTime);
    lastTime = currTime;
  }
}

NRF52_MBED_Timer's TimerHandler delay 

// Arduino Nano 33 BLE

#define TIMER_INTERRUPT_DEBUG         0
#define _TIMERINTERRUPT_LOGLEVEL_     0
#define HW_TIMER_INTERVAL_MS      1

#include "NRF52_MBED_TimerInterrupt.h"
#include "NRF52_MBED_ISR_Timer.h"

NRF52_MBED_Timer ITimer(NRF_TIMER_3);

// Init NRF52 timer NRF_TIMER3
NRF52_MBED_Timer ITimer(NRF_TIMER_3);
// Init NRF52_MBED_ISRTimer
// Each NRF52_MBED_ISRTimer can service 16 different ISR-based timers
NRF52_MBED_ISRTimer ISR_Timer;

#define TIMER_INTERVAL_1s    1000L

volatile static unsigned int count = 0;
void TimerHandler() {
    count += 1;
    if (count % 100000 == 0) // **** should happen every 1 sec? - does not work
        digitalWrite(LED_PWR, !digitalRead(LED_PWR)); 
    ISR_Timer.run();
}


void onTimer1s() { // once per 1 sec. - it works
     digitalWrite(LED_BUILTIN, !digitalRead(LED_BUILTIN));
   }


void setup() {
    // Interval in microsecs
    if (ITimer.attachInterruptInterval(HW_TIMER_INTERVAL_MS * 1000/100, TimerHandler)) {  // **** every 10 us?
        // Serial.print(F("Starting ITimer OK, millis() = ")); Serial.println(millis());
    } else {
       //  Serial.println(F("Can't set ITimer. Select another freq. or timer"));
    }
    ISR_Timer.setInterval(TIMER_INTERVAL_1s, onTimer1s); 
 }


void loop() {
}

For some reason LED_PWR blink are about twice as slow... onTimer1s works as expected.

analogRead

I tried using the Argument_None Example that you have on Ardiuno Nano 33 Sense and it worked perfectly fine.
The issue is whenever I add a analogRead within any of the Interrupt Service Routines the program will freeze after the first printResult function. To even upload a new sketch the Ardiuno Nano 33 Sense has to be but into bootloader mode.

Procedure For Installing MBED 1.3.2

I'm using a Nano 33 BLE, and the Arduino IDE.

I know that Timer 1 doesn't work for the latest MBED versions, which I discovered myself before reading other peoples reports.

Therefore, I have two questions...

  1. Please describe the procedure for installing MBED 1.3.2 (and will this then mean that timer 1 will work after doing this?)

  2. Does this library make use of all 16 bit timers, e.g., will 10 micro seconds (or even lower, perhaps 1) be accurate? like when setting registers directly, as demonstrated in various AVR examples.

Thank you, Gary.

Edit 1: ah! so for micro second precision we need the following maybe...

#include <hal/nrf_timer.h>
#include <hal/nrf_gpiote.h>
#include <hal/nrf_gpio.h>
#include <hal/nrf_ppi.h>

Please kindly confirm if this library uses the above for the Nano 33 BLE?

Edit 2: my sincere apologies for editing again, but I'm trying to understand the fundamentals...

NRF52840 Timers... "5×32 bit 16MHz Timer"

So for the Nano 33 BLE... is this correct? so potentially extremely accurate via using the GPIOTE.

Edit 3: the timers are listed in the 1st table on this page as well Nordic's NRF52 Timer Info

Issue w/ AnalogRead in Interrupt

Hi Khoi,
Thanks for writing and sharing this timer interrupt library.
I am trying to implement consistently spaced sampling on a Nano33BLE, but the board seems to crash whenever I have a call to analogRead within the ISR.

Arduino IDE version: 1.8.13
Arduino mbed Nano Core Version 2.4.1
OS: Windows 10

Minimal code is below. I have also tried with an Adafruit nrf52 board and your other version of the library. This seems to work, but only if interrupts are halted before the analogRead call and enabled afterwards.

Working on native Nordic SDK firmware, but it would be great to accelerate prototyping with your library!

// test of timer ADC functionality

#include "NRF52_MBED_TimerInterrupt.h"

#define MOTOR_PIN P0_27 // 9u, D9
#define OPTO_PIN P0_21 // 8u, D8
#define FIELD_MILL_PIN P0_5 // 15u, A1

#define SAMPLE_INTERVAL 500
#define BLE_INTERVAL 10000

NRF52_MBED_Timer sample_timer(NRF_TIMER_4);
NRF52_MBED_Timer ble_timer(NRF_TIMER_3);

volatile int idx;
volatile unsigned long times[20] = {};
volatile int readings[20] = {};
volatile int fm_output = 0;

unsigned long t_now; // start time for current loop
unsigned long t_last_sample = 0;
unsigned long sample_delay = 5000;
unsigned long t_last_print = 0;
unsigned long print_delay = 500E3;

void setup() {
// put your setup code here, to run once:

Serial.begin(57600);

analogReadResolution(12);

sample_timer.attachInterruptInterval(SAMPLE_INTERVAL, SampleTimerFunc);
ble_timer.attachInterruptInterval(BLE_INTERVAL, BleTimerFunc);

}

void loop() {
// put your main code here, to run repeatedly:

t_now = micros();
// if (t_now - t_last_sample > sample_delay)
// {
// t_last_sample = t_now;
// times[idx] = micros();
// readings[idx] = analogRead(FIELD_MILL_PIN);
// idx++;
// if (idx >= 20)
// {
// idx = 0;
// }
// }

// Print debug data
if (t_now - t_last_print > print_delay)
{
t_last_print = t_now;
Serial.println(fm_output);
for (int i = 0; i < 20; i++)
{
Serial.print(times[i]);
Serial.print("\t");
}
Serial.println();
for (int i = 0; i < 20; i++)
{
Serial.print(readings[i]);
Serial.print("\t");
}
Serial.println();
}
}

void SampleTimerFunc()
{
times[idx] = micros();
// noInterrupts();
readings[idx] = analogRead(FIELD_MILL_PIN);
// interrupts();
// readings[idx] = 200;

idx++;
if (idx >= 20)
{
idx = 0;
}
}

void BleTimerFunc()
{
int total = 0;
for (int i = 0; i < 20; i++)
{
total += readings[i];
}
fm_output = (int)(76.0 * (double)total / 20.0);
}

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