Need some advice on a Digital Potentiometer

Forum 2005-2010 (read only) General Frequently-Asked Questions
21

Here's the code for the Microchip MCP4261 http://www.microchip.com/wwwproducts/Devices.aspx?dDocName=en531252.

Right now it's in bit banging mode (as in note using native spi, but it's very, very fast).

//Barry's hacky functions

byte value;

byte sendBit(boolean state)
{
  digitalWrite(SPICLOCK,LOW);
  delayMicroseconds(10);
  digitalWrite(DATAOUT,state);
  digitalWrite(SPICLOCK,HIGH);
  delayMicroseconds(10);
}

byte sendValue(int wiper, int val)
//tested cycle time for this function is ~565 microseconds.
{
  value =  byte(val);
  //digitalWrite(SPICLOCK,LOW);
  //digitalWrite(DATAOUT,LOW);
  digitalWrite(SLAVESELECTP,LOW);
  delayMicroseconds(10);

  //Select wiper
  for(int i=0;i<3;i++){
    sendBit(false);
  }
  sendBit(wiper);

  //write command
  for(int i=0;i<4;i++){
    sendBit(false);
  }
  //data
  sendBit(HIGH && (value & B10000000));
  sendBit(HIGH && (value & B01000000));
  sendBit(HIGH && (value & B00100000));
  sendBit(HIGH && (value & B00010000));
  sendBit(HIGH && (value & B00001000));
  sendBit(HIGH && (value & B00000100));
  sendBit(HIGH && (value & B00000010));
  sendBit(HIGH && (value & B00000001));
  //sendBit(true);  //fudge
  digitalWrite(SLAVESELECTP,HIGH);
  //Serial.println(in);
  delayMicroseconds(10);
}

byte readWiper()
{
  //send read command
  digitalWrite(SLAVESELECTP,LOW);
  delayMicroseconds(10);
  sendBit(false);
  sendBit(false);
  sendBit(false);
  sendBit(false);
  sendBit(true);
  sendBit(true);

  //get data
  int data[9];
  Serial.print("  ");
  for(int i=0;i<9;i++)
  {
    digitalWrite(SPICLOCK,LOW);
    delayMicroseconds(10);
    digitalWrite(DATAOUT,LOW);
    delayMicroseconds(10);
    data[i] = digitalRead(DATAIN);
    digitalWrite(SPICLOCK,HIGH);
    delayMicroseconds(10);
    Serial.print(data[i]);
  }
  digitalWrite(SLAVESELECTP,HIGH);
}