marlin-lulzbot-laser/Marlin/digipot_mcp4451.cpp

#include "Configuration.h"

#ifdef DIGIPOT_I2C

#include "Stream.h"
#include "utility/twi.h"
#include "Wire.h"

// Settings for the I2C based DIGIPOT (MCP4451) on Azteeg X3 Pro
#if MB(5DPRINT)
  #define DIGIPOT_I2C_FACTOR 117.96
  #define DIGIPOT_I2C_MAX_CURRENT 1.736
#else
  #define DIGIPOT_I2C_FACTOR 106.7
  #define DIGIPOT_I2C_MAX_CURRENT 2.5
#endif

static byte current_to_wiper(float current) {
  return byte(ceil(float((DIGIPOT_I2C_FACTOR*current))));
}

static void i2c_send(byte addr, byte a, byte b) {
  Wire.beginTransmission(addr);
  Wire.write(a);
  Wire.write(b);
  Wire.endTransmission();
}

// This is for the MCP4451 I2C based digipot
void digipot_i2c_set_current(int channel, float current) {
  current = min( (float) max( current, 0.0f ), DIGIPOT_I2C_MAX_CURRENT);
  // these addresses are specific to Azteeg X3 Pro, can be set to others,
  // In this case first digipot is at address A0=0, A1= 0, second one is at A0=0, A1= 1
  byte addr = 0x2C; // channel 0-3
  if (channel >= 4) {
  	addr = 0x2E; // channel 4-7
  	channel -= 4;
  }

  // Initial setup
  i2c_send(addr, 0x40, 0xff);
  i2c_send(addr, 0xA0, 0xff);

  // Set actual wiper value
  byte addresses[4] = { 0x00, 0x10, 0x60, 0x70 };
  i2c_send(addr, addresses[channel], current_to_wiper(current));
}

void digipot_i2c_init() {
  const float digipot_motor_current[] = DIGIPOT_I2C_MOTOR_CURRENTS;
  Wire.begin();
  // setup initial currents as defined in Configuration_adv.h
  for(int i = 0; i <= sizeof(digipot_motor_current) / sizeof(float); i++) {
    digipot_i2c_set_current(i, digipot_motor_current[i]);
  }
}

#endif //DIGIPOT_I2C