tardisgallifrey / ads1115 Goto Github PK

WARNING Use of this code or anything here is given without warranty for any purpose. USE AT YOUR OWN RISK.

Update 6/21/2020: added adsget.c and modded Makefile to adapt.

06/21/2020: run "make clean simple" to produce ads_get. ads_get takes numbers on command line for address, ai line, and gain. Will produce one read of ai line. This is prep for use in PHP and other programs.

example: ads_get 1 2 2 (where 1 = address 0x48, 2 = ain2, and 2 = voltage range 4.096 (for 5V and 3.3V))

Short cut: If you fork this repo to your own Raspberry Pi, you should be able to run "make clean default" in order to produce the current version of ads_read.

Run this with "sudo ./ads_read" on Linux and you ought to get a stream from STD_IN on your terminal with the voltage of your chosen AI line (configured in the program) on the ADS1115.

Long story: A C based package (more or less) to read analog values from an ADS1115 A/D board.

I give original credit to Lewis Loflin at bristolwatch.com as he was the one that deciphered the cut sheet for the ADS1115 register instructions.

I have altered the original C code to function-ize the basic register calling and turn it into a returned decimal value (0-32767).

I also put the function into its own file so that one can write code using the function without having to keep track of the function itself.

The function definition is given below:

int16_t ads_read( int address, int ain, int gain );

The function depends upon a header file where I define the needed binary sorted numbers that make up the configuration register.

The ADS1115 can be set up easily to be one of four I2C bus addresses.

The variable 'address' is set to be one of the following for predefined values: HEX48 HEX49 HEX4A HEX4B

The function makes use of a bit setting for either 1-shot read and shutdown operation or continuous read. Loewis didn't go into continuous read much and the 1-shot setting works well, so I've set it permanently in the function.

There are four analog inputs on the ADS1115 board. The following predefined values tell which one to read from. AI0 AI1 AI2 AI3

There is also a gain setting for the AI and the following predefined settings set that on a read cycle. GAIN2 works for most 3.3V and 5V inputs.

GAIN1 through GAIN8

Making a program that makes it easier to read and display (or return) a value and the ability of addressing multiple boards, means that one could have an I2C enabled device that could easily read up to 16 0-3.3VDC or 0-5VDC sensors.

Things to do:

1. Currently working on a main program that reads function values from the command line and returns the value (in progress, see adsget.c).
2. Plan to write program such that it can be used with PHP to display an analog input value in a web page.
3. Not a programming task, but experiment with a way to use opto-isolators in the SDA/SCL lines so that the ADS1115 can be used at 5VDC but still operate on the Raspberry PI 3.3VDC enabled I2C bus.
4. Currently, working on porting this project over to C++, C# (.NET), and possibly Go. There will be future folders appearing when these begin to be finalized.