MCP4725 Digital to Analog Converter Hookup Guide

Contributors: Joel_E_B

Firmware

With everything hooked up, it's time to upload some code to the Arduino that will allow the breakout to send analog signals. In this example, the code will generate a simple sine wave.

Open up the Arduino IDE, and copy in this snippet of code:

language:c
/****************************************************************************** 
MCP4725 Example Waveform Sketch
Joel Bartlett
SparkFun Electronics
Sept. 11, 2014
https://github.com/sparkfun/MCP4725_Breakout

This sketch takes data from a lookup table to provide 
waveforms to be generated by the MCP4725 DAC. 

Development environment specifics:
Arduino 1.0+
Hardware Version V14

This code is beerware; if you see me (or any other SparkFun employee) at the local, 
and you've found our code helpful, please buy us a round!

Distributed as-is; no warranty is given. 

This code builds off the sketch written by Mark VandeWettering, which can be found here:
http://brainwagon.org/2011/02/24/arduino-mcp4725-breakout-board/
*/

#include <Wire.h>//Include the Wire library to talk I2C

//This is the I2C Address of the MCP4725, by default (A0 pulled to GND).
//Please note that this breakout is for the MCP4725A0. 
#define MCP4725_ADDR 0x60   
//For devices with A0 pulled HIGH, use 0x61

//Sinewave Tables were generated using this calculator:
//http://www.daycounter.com/Calculators/Sine-Generator-Calculator.phtml


int lookup = 0;//varaible for navigating through the tables

int sintab2[512] = 
{
  2048, 2073, 2098, 2123, 2148, 2174, 2199, 2224,
  2249, 2274, 2299, 2324, 2349, 2373, 2398, 2423,
  2448, 2472, 2497, 2521, 2546, 2570, 2594, 2618,
  2643, 2667, 2690, 2714, 2738, 2762, 2785, 2808,
  2832, 2855, 2878, 2901, 2924, 2946, 2969, 2991,
  3013, 3036, 3057, 3079, 3101, 3122, 3144, 3165,
  3186, 3207, 3227, 3248, 3268, 3288, 3308, 3328,
  3347, 3367, 3386, 3405, 3423, 3442, 3460, 3478,
  3496, 3514, 3531, 3548, 3565, 3582, 3599, 3615,
  3631, 3647, 3663, 3678, 3693, 3708, 3722, 3737,
  3751, 3765, 3778, 3792, 3805, 3817, 3830, 3842,
  3854, 3866, 3877, 3888, 3899, 3910, 3920, 3930,
  3940, 3950, 3959, 3968, 3976, 3985, 3993, 4000,
  4008, 4015, 4022, 4028, 4035, 4041, 4046, 4052,
  4057, 4061, 4066, 4070, 4074, 4077, 4081, 4084,
  4086, 4088, 4090, 4092, 4094, 4095, 4095, 4095,
  4095, 4095, 4095, 4095, 4094, 4092, 4090, 4088,
  4086, 4084, 4081, 4077, 4074, 4070, 4066, 4061,
  4057, 4052, 4046, 4041, 4035, 4028, 4022, 4015,
  4008, 4000, 3993, 3985, 3976, 3968, 3959, 3950,
  3940, 3930, 3920, 3910, 3899, 3888, 3877, 3866,
  3854, 3842, 3830, 3817, 3805, 3792, 3778, 3765,
  3751, 3737, 3722, 3708, 3693, 3678, 3663, 3647,
  3631, 3615, 3599, 3582, 3565, 3548, 3531, 3514,
  3496, 3478, 3460, 3442, 3423, 3405, 3386, 3367,
  3347, 3328, 3308, 3288, 3268, 3248, 3227, 3207,
  3186, 3165, 3144, 3122, 3101, 3079, 3057, 3036,
  3013, 2991, 2969, 2946, 2924, 2901, 2878, 2855,
  2832, 2808, 2785, 2762, 2738, 2714, 2690, 2667,
  2643, 2618, 2594, 2570, 2546, 2521, 2497, 2472,
  2448, 2423, 2398, 2373, 2349, 2324, 2299, 2274,
  2249, 2224, 2199, 2174, 2148, 2123, 2098, 2073,
  2048, 2023, 1998, 1973, 1948, 1922, 1897, 1872,
  1847, 1822, 1797, 1772, 1747, 1723, 1698, 1673,
  1648, 1624, 1599, 1575, 1550, 1526, 1502, 1478,
  1453, 1429, 1406, 1382, 1358, 1334, 1311, 1288,
  1264, 1241, 1218, 1195, 1172, 1150, 1127, 1105,
  1083, 1060, 1039, 1017,  995,  974,  952,  931,
   910,  889,  869,  848,  828,  808,  788,  768,
   749,  729,  710,  691,  673,  654,  636,  618,
   600,  582,  565,  548,  531,  514,  497,  481,
   465,  449,  433,  418,  403,  388,  374,  359,
   345,  331,  318,  304,  291,  279,  266,  254,
   242,  230,  219,  208,  197,  186,  176,  166,
   156,  146,  137,  128,  120,  111,  103,   96,
    88,   81,   74,   68,   61,   55,   50,   44,
    39,   35,   30,   26,   22,   19,   15,   12,
    10,    8,    6,    4,    2,    1,    1,    0,
     0,    0,    1,    1,    2,    4,    6,    8,
    10,   12,   15,   19,   22,   26,   30,   35,
    39,   44,   50,   55,   61,   68,   74,   81,
    88,   96,  103,  111,  120,  128,  137,  146,
   156,  166,  176,  186,  197,  208,  219,  230,
   242,  254,  266,  279,  291,  304,  318,  331,
   345,  359,  374,  388,  403,  418,  433,  449,
   465,  481,  497,  514,  531,  548,  565,  582,
   600,  618,  636,  654,  673,  691,  710,  729,
   749,  768,  788,  808,  828,  848,  869,  889,
   910,  931,  952,  974,  995, 1017, 1039, 1060,
  1083, 1105, 1127, 1150, 1172, 1195, 1218, 1241,
  1264, 1288, 1311, 1334, 1358, 1382, 1406, 1429,
  1453, 1478, 1502, 1526, 1550, 1575, 1599, 1624,
  1648, 1673, 1698, 1723, 1747, 1772, 1797, 1822,
  1847, 1872, 1897, 1922, 1948, 1973, 1998, 2023
};


void setup()
{
  Wire.begin();

  // Set A2 and A3 as Outputs to make them our GND and Vcc,
  //which will power the MCP4725
  pinMode(A2, OUTPUT);
  pinMode(A3, OUTPUT);

  digitalWrite(A2, LOW);//Set A2 as GND
  digitalWrite(A3, HIGH);//Set A3 as Vcc
}
//---------------------------------------------------
void loop()
{
  Wire.beginTransmission(MCP4725_ADDR);
  Wire.write(64);                     // cmd to update the DAC
  Wire.write(sintab2[lookup] >> 4);        // the 8 most significant bits...
  Wire.write((sintab2[lookup] & 15) << 4); // the 4 least significant bits...
  Wire.endTransmission();
  lookup = (lookup + 1) & 511;
}

Once the sketch is uploaded, fire up the o-scope, connect the probe, if you haven't yet, and you should be greeted with a nice looking sine wave.