reprapfirmware-dc42/Libraries/MCP4461/MCP4461.cpp

#include "MCP4461.h"

/*
Library to control the MCP4461 Digital Potentiometer over I2C.
http://ww1.microchip.com/downloads/en/DeviceDoc/22265a.pdf
This library does not fully implement the functionality of
the MCP4461 – just the basics of changing the wiper values.
Note this is currently configured to use the second I2C bus
on the Due: Wire1
The master joins the bus with the default address of 0

No warranty given or implied, use at your own risk.
Tony@think3dprint3d.com
GPL v3
*/

#include <stdio.h>
#include <Wire.h>

//ensure you call begin() before any other functions but note
//begin can only be called once for all MCP* objects as it initialises
//the local master through the Wire library
//if the MCP4461 does not have a default address, call set address before
//trying to communicate
MCP4461::MCP4461() {
  _mcp4461_address = DEFAULT_ADDRESS;
}

//initialise the I2C interface as master ie local address is 0
void MCP4461::begin() {
    Wire1.begin();
}

//set the MCP4461 address
void MCP4461::setMCP4461Address(uint8_t mcp4461_addr) {
	_mcp4461_address = mcp4461_addr;
}

void MCP4461::setVolatileWiper(uint8_t wiper, uint16_t wiper_value){
  uint16_t value = wiper_value;
  if (value > 0xFF) value = 0x100;
  uint8_t d_byte = (uint8_t)value;
  uint8_t c_byte;
  if (value > 0xFF)c_byte = 0x1; //the 8th data bit is 1
  else c_byte =0;
  switch (wiper) {
      case 0:
        c_byte |= MCP4461_VW0;
        break;
      case 1:
        c_byte |= MCP4461_VW1;
        break;
      case 2:
        c_byte |= MCP4461_VW2;
        break;
      case 3:
        c_byte |= MCP4461_VW3;
        break;
      default: 
        break; //not a valid wiper
  } 
  c_byte |= MCP4461_WRITE;
  //send command byte
  Wire1.beginTransmission(_mcp4461_address);
  Wire1.write(c_byte);
  Wire1.write(d_byte);
  Wire1.endTransmission(); //do not release bus
  }

void MCP4461::setNonVolatileWiper(uint8_t wiper, uint16_t wiper_value){
  uint16_t value = wiper_value;
  if (value > 0xFF) value = 0x100;
  uint8_t d_byte = (uint8_t)value;
  uint8_t c_byte;
  if (value > 0xFF)c_byte = 0x1; //the 8th data bit is 1
  else c_byte =0;
  switch (wiper) {
      case 0:
        c_byte |= MCP4461_NVW0;
        break;
      case 1:
        c_byte |= MCP4461_NVW1;
        break;
      case 2:
        c_byte |= MCP4461_NVW2;
        break;
      case 3:
        c_byte |= MCP4461_NVW3;
        break;
      default: 
        break; //not a valid wiper
  } 
  c_byte |= MCP4461_WRITE;
  //send command byte
  Wire1.beginTransmission(_mcp4461_address);
  Wire1.write(c_byte);
  Wire1.write(d_byte);
  Wire1.endTransmission(); //do not release bus
  delay(20); //allow the write to complete (this is wasteful - better to check if the write has completed)
  }
  
//set all the wipers in one transmission, more verbose but quicker than multiple calls to
//setVolatileWiper(uint8_t wiper, uint16_t wiper_value)
void MCP4461::setVolatileWipers(uint16_t wiper_value){
  uint16_t value = wiper_value;
  if (value > 0xFF) value = 0x100;
  uint8_t d_byte = (uint8_t)value;
  uint8_t c_byte;
  if (value > 0xFF)c_byte = 0x1; //the 8th data bit is 1
  else c_byte =0;
  Wire1.beginTransmission(_mcp4461_address);
  c_byte |= MCP4461_WRITE;
  c_byte |= MCP4461_VW0;
  Wire1.write(c_byte);
  Wire1.write(d_byte);
  if (value > 0xFF) c_byte = 0x1;
  else c_byte =0;
  c_byte |= MCP4461_WRITE;
  c_byte |= MCP4461_VW1;
  Wire1.write(c_byte);
  Wire1.write(d_byte);
  if (value > 0xFF) c_byte = 0x1;
  else c_byte =0;
  c_byte |= MCP4461_WRITE;
  c_byte |= MCP4461_VW2;
  Wire1.write(c_byte);
  Wire1.write(d_byte);
  if (value > 0xFF) c_byte = 0x1;
  else c_byte =0;
  c_byte |= MCP4461_WRITE;
  c_byte |= MCP4461_VW3;
  Wire1.write(c_byte);
  Wire1.write(d_byte);
  Wire1.endTransmission();
}

//set all the wipers in one transmission, more verbose but quicker than multiple calls to
//setNonVolatileWiper(uint8_t wiper, uint16_t wiper_value)
void MCP4461::setNonVolatileWipers(uint16_t wiper_value){
 uint16_t value = wiper_value;
  if (value > 0xFF) value = 0x100;
  uint8_t d_byte = (uint8_t)value;
  uint8_t c_byte;
  if (value > 0xFF)c_byte = 0x1; //the 8th data bit is 1
  else c_byte =0;
  Wire1.beginTransmission(_mcp4461_address);
  c_byte |= MCP4461_WRITE;
  c_byte |= MCP4461_NVW0;
  Wire1.write(c_byte);
  Wire1.write(d_byte);
  delay(20); //allow the write to complete (this is wasteful - better to check if the write has completed)
  if (value > 0xFF) c_byte = 0x1;
  else c_byte =0;
  c_byte |= MCP4461_WRITE;
  c_byte |= MCP4461_NVW1;
  Wire1.write(c_byte);
  Wire1.write(d_byte);
  delay(20);
  if (value > 0xFF) c_byte = 0x1;
  else c_byte =0;
  c_byte |= MCP4461_WRITE;
  c_byte |= MCP4461_NVW2;
  Wire1.write(c_byte);
  Wire1.write(d_byte);
  delay(20);
  if (value > 0xFF) c_byte = 0x1;
  else c_byte =0;
  c_byte |= MCP4461_WRITE;
  c_byte |= MCP4461_NVW3;
  Wire1.write(c_byte);
  Wire1.write(d_byte);
  Wire1.endTransmission();
  delay(20);
}

//return the value for a specific wiper
uint16_t MCP4461::getNonVolatileWiper(uint8_t wiper){
  uint16_t ret = 0;
  uint16_t c_byte =0;
  switch (wiper) {
      case 0:
        c_byte |= MCP4461_NVW0;
        break;
      case 1:
        c_byte |= MCP4461_NVW1;
        break;
      case 2:
        c_byte |= MCP4461_NVW2;
        break;
      case 3:
        c_byte |= MCP4461_NVW3;
        break;
      default: 
        return 0; //not a valid wiper
  } 
  c_byte |= MCP4461_READ; 
  //send command byte
  Wire1.beginTransmission(_mcp4461_address);
  Wire1.write(c_byte);
  Wire1.endTransmission(false); //do not release bus
  Wire1.requestFrom((uint8_t)_mcp4461_address,(uint8_t)2);
  //read the register
  int i = 0;
  while(Wire1.available()) 
  { 
    ret |= Wire1.read();
    if (i==0) ret = ret<<8;
    i++;
  }
  return ret;
}
  
//return the volatile value for a specific wiper
uint16_t MCP4461::getVolatileWiper(uint8_t wiper){
  uint16_t ret = 0;
  uint16_t c_byte =0;
  switch (wiper) {
      case 0:
        c_byte |= MCP4461_VW0;
        break;
      case 1:
        c_byte |= MCP4461_VW1;
        break;
      case 2:
        c_byte |= MCP4461_VW2;
        break;
      case 3:
        c_byte |= MCP4461_VW3;
        break;
      default: 
        return 0; //not a valid wiper
  } 
  c_byte |= MCP4461_READ; 
  //send command byte
  Wire1.beginTransmission(_mcp4461_address);
  Wire1.write(c_byte);
  Wire1.endTransmission(false); //do not release bus
  Wire1.requestFrom((uint8_t)_mcp4461_address,(uint8_t)2);
  //read the register
  int i = 0;
  while(Wire1.available()) 
  { 
    ret |= Wire1.read();
    if (i==0) ret = ret<<8;
    i++;
  }
  return ret;
} 


//return the status register
uint16_t MCP4461::getStatus(){
  uint16_t ret = 0;
  uint16_t c_byte =0;
  c_byte |= MCP4461_STATUS;
  c_byte |= MCP4461_READ; 
  //send command byte
  Wire1.beginTransmission(_mcp4461_address);
  Wire1.write(c_byte);
  Wire1.endTransmission(false); //do not release bus
  Wire1.requestFrom((uint8_t)_mcp4461_address, (uint8_t)2);
  //read the register
  int i = 0;
  while(Wire1.available()) 
  { 
    ret |= Wire1.read();
    if (i==0) ret = ret<<8;
    i++;
  }
  return ret;
}

//toggle a specific pot channel on and off
/*  //NOT YET IMPLEMENTED
void MCP4461::toggleWiper(uint8_t wiper){
  uint16_t tcon = 0;
  uint16_t c_byte =0;
  //read the specific TCONX register to get the current stae of the
  //pot connections
  if (wiper <=1) {
    c_byte |= MCP4461_TCON0;  
    c_byte |= MCP4461_READ;
  }
  else {
    c_byte |= MCP4461_TCON1;  
    c_byte |= MCP4461_READ;
  }
  //send command byte
  Wire1.beginTransmission(_mcp4461_address);
  Wire1.write(c_byte);
  Wire1.endTransmission(false); //do not release bus
  Wire1.requestFrom((uint8_t)_mcp4461_address,(uint8_t)2);
  //read the register
  int i = 0;
  while(Wire1.available()) 
  { 
    tcon |= Wire1.read();
    if (i==0) tcon = tcon<<8;
    i++;
  }
  SerialUSB.print(" TCON ");
  SerialUSB.print(tcon,BIN);
} */