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Limor "Ladyada" Fried February 14, 2014
file 83 lines (70 sloc) 2.556 kb
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/**************************************************************************/
/*!
@file Adafruit_MCP4725.cpp
@author K.Townsend (Adafruit Industries)
@license BSD (see license.txt)
I2C Driver for Microchip's MCP4725 I2C DAC

This is a library for the Adafruit MCP4725 breakout
----> http://www.adafruit.com/products/935
Adafruit invests time and resources providing this open source code,
please support Adafruit and open-source hardware by purchasing
products from Adafruit!

@section HISTORY

v1.0 - First release
*/
/**************************************************************************/
#if ARDUINO >= 100
#include "Arduino.h"
#else
#include "WProgram.h"
#endif

#include <Wire.h>

#include "Adafruit_MCP4725.h"

/**************************************************************************/
/*!
@brief Instantiates a new MCP4725 class
*/
/**************************************************************************/
Adafruit_MCP4725::Adafruit_MCP4725() {
}

/**************************************************************************/
/*!
@brief Setups the HW
*/
/**************************************************************************/
void Adafruit_MCP4725::begin(uint8_t addr) {
  _i2caddr = addr;
  Wire.begin();

}
 
/**************************************************************************/
/*!
@brief Sets the output voltage to a fraction of source vref. (Value
can be 0..4095)

@param[in] output
The 12-bit value representing the relationship between
the DAC's input voltage and its output voltage.
@param[in] writeEEPROM
If this value is true, 'output' will also be written
to the MCP4725's internal non-volatile memory, meaning
that the DAC will retain the current voltage output
after power-down or reset.
*/
/**************************************************************************/
void Adafruit_MCP4725::setVoltage( uint16_t output, bool writeEEPROM )
{
  uint8_t twbrback = TWBR;
  TWBR = ((F_CPU / 400000L) - 16) / 2; // Set I2C frequency to 400kHz
  Wire.beginTransmission(_i2caddr);
  if (writeEEPROM)
  {
    Wire.write(MCP4726_CMD_WRITEDACEEPROM);
  }
  else
  {
    Wire.write(MCP4726_CMD_WRITEDAC);
  }
  Wire.write(output / 16); // Upper data bits (D11.D10.D9.D8.D7.D6.D5.D4)
  Wire.write((output % 16) << 4); // Lower data bits (D3.D2.D1.D0.x.x.x.x)
  Wire.endTransmission();
  TWBR = twbrback;
}
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