Signal_Generator

Author: Dean Souleles, KK4DAS Revision: 1.0, 25-Jan-2020

Description:

The signal generator outputs a sine wave from DC to ~62 MHz using an Arduino Nano and Analog Devices AD9850 Direct Digital Synthesizer. A 10K linear taper potentiometer is used as a variable attenuator. The display is 16x2 I2C LCD. The control is a Rotary Digital Encoder with push button. Turn the encoder to change frequency Push the button to select the tuning increment.

There are various versions of this floating around the internet. This is my implementation

Build Instructions:

 Download the Arduino DDS Library by Paul Darlinton, M0XPD and install using the Arduino IDE library manager.
        https://github.com/m0xpd/DDS
        http://m0xpd.blogspot.com/2014/03/dds-and-duedds-libraries.html
 
 
 Create a folder called KK4DASSigGen and install the the source files there.  The main sketch is KK4DASSigGen.ino.  Open it in the 
 Arduino IDE. It should compile with no errors.
 
 A schematic and Fritzing diagram are included for reference.

Components:

  Arduino Nano
  
  DDS Signal Generator Module - any one of the AD9850 boards should work. I used each of these at different times:
    https://www.amazon.com/HiLetgo-AD9850-Generator-0-40MHz-Equipment/dp/B01J7XPWNU/
    https://www.amazon.com/gp/product/B082143FD9 
  Data sheet: https://www.analog.com/media/en/technical-documentation/data-sheets/AD9850.pdf

  16x2 I2C LCD display
        https://www.amazon.com/JANSANE-Arduino-Display-Interface-Raspberry/dp/B07D83DY17

  Rotary Encoder with switch
        https://www.mouser.com/ProductDetail/652-PEC11R-4020F-S24

  10K Linear Taper Potentiometer
        https://www.mouser.com/ProductDetail/Bourns/PDB181-K415K-103B?qs=Zq5ylnUbLm7hRcKeZmRxRw%3D%3D

Enclosure and permanent mounting:

  Enclosure - 4"x3" plastic enclosure
        https://www.mpja.com/4in-X-3in-X-16in-Black-Plastic-Box-Enclosure/productinfo/15523+BX/ 

  Panel mount BNC Connector
        https://www.mpja.com/BNC-Type-Connector-UG-1094-Female-Single-Hole-Mount/productinfo/20507+RC/ 

  PCBs = two Adafruit 1/4 sized breadboard PCBs, one for the Arduino and one for the AD-9850 module
        https://www.adafruit.com/product/589

  Mounting hardware - 4-40 standoffs and spacers, machine screws, washers and nuts

  Optional - 0.1" female headers on the breadboard make it easy to wire the components up in the case

Wiring:

AD9850	Arduino
W_CLK	Pin 8 - connect to AD9850 module word load clock pin (CLK)
FQ_UD	Pin 9 - connect to freq update pin (FQ)
DATA	Pin 10 - connect to serial data load pin (DATA)
RESET	Pin 11 - connect to reset pin (RST)
VCC	+5
Gnd	Gnd

Encoder	Arduino
A	2 - Encoder pin A D2 (interrupt pin)
B	3 - Encoder pin B D3 (interrupt pin)
BTN	A3 - Encoder push button

LCD/I2C	Arduino
SDA	4
SCL	5
VCC	+5
Gnd	Gnd

Pot	Connects to
1	AD-9850 Sin B
2	Wiper goes to center pin of BNC
3	Gnd

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