//
//    FILE: hmc6352.cpp
//  AUTHOR: Rob Tillaart
// VERSION: 0.1.03
// PURPOSE: HMC6352 library for Arduino
//
// HISTORY:
// 0.1.00 - 2011-04-07 initial version
// 0.1.01 - 2011-04-09 quite a complete redo
// 0.1.02 - 2011-04-12 added timing, fixed a bug
// 0.1.03 - 2011-04-13 fixed small things; added getHeading()
// 0.1.4  - 2017-09-13 minor refactor
//
// Released to the public domain
//

#include <hmc6352.h>
#include <Wire.h>

#if defined(ARDUINO) && ARDUINO >= 100
#define WIRE_WRITE Wire.write
#define WIRE_READ  Wire.read
#else
#define WIRE_WRITE Wire.send
#define WIRE_READ  Wire.receive
#endif

/* ERROR CODES ALL FUNCTIONS
//
// * twi_writeTo codes (== endTransmission  commands)
//   0 .. OK
//  -1 .. length to long for buffer
//  -2 .. address send, NACK received
//  -3 .. data send, NACK received
//  -4 .. other twi error (lost bus arbitration, bus error, ..)
//
// * requestFrom
// -10 .. not enough values returned
//
// * function calls
//   0 .. OK
// -20 .. error param1
// -21 .. error param2
// -22 .. error param3
//
*/

hmc6352::hmc6352(uint8_t device)
{
  Wire.begin();
  _device = constrain(device, 0x10, 0xF6);
}

int hmc6352::getHeading()
{
  int rv = askHeading();
  if (rv != 0) return rv;
  return readHeading();
}

// Ask the device to make a new reading
int hmc6352::askHeading()
{
  int rv = cmd(HMC_GET_DATA);
  if (rv != 0) return -rv;   // problem with handshake
  delay(6); // see datasheet, p8
  return rv;
}

// read the last value from the
int hmc6352::readHeading()
{
  int rv = Wire.requestFrom(_device, (uint8_t)2);  // remove ambiguity
  if (rv != 2) return -10;
  rv = WIRE_READ() * 256;  // MSB
  rv += WIRE_READ();       // LSB
  return rv;
}

// wake up from energy saving modus
int hmc6352::wakeUp()
{
  int rv =  cmd(HMC_WAKE);
  delayMicroseconds(100);
  return rv;
}

// go into energy saving modus
int hmc6352::sleep()
{
  int rv = cmd(HMC_SLEEP);
  delayMicroseconds(10);
  return rv;
}

// values obtained from dump
int hmc6352::factoryReset()
{
  writeRAM(0x74, 0x50); // is needed !!
  writeCmd(HMC_WRITE_EEPROM, 0, 66);
  writeCmd(HMC_WRITE_EEPROM, 1, 0);
  writeCmd(HMC_WRITE_EEPROM, 2, 0);
  writeCmd(HMC_WRITE_EEPROM, 3, 0);
  writeCmd(HMC_WRITE_EEPROM, 4, 0);
  writeCmd(HMC_WRITE_EEPROM, 5, 1);
  writeCmd(HMC_WRITE_EEPROM, 6, 4);
  writeCmd(HMC_WRITE_EEPROM, 7, 6);
  writeCmd(HMC_WRITE_EEPROM, 8, 0x50);
  cmd(HMC_SAVE_OP_MODE);
  delayMicroseconds(125);
  return 0;
}

// HANDLE WITH CARE - RESTART NECESSARY
// Returns Operational Mode Config Byte
int hmc6352::setOperationalModus(hmcMode m, uint8_t freq, bool periodicReset)
{
  byte omcb = 0;  // Operational Mode Control Byte
  switch(freq)
  {
  case 1: break;
  case 5: omcb |= 0x20; break;
  case 10: omcb |= 0x40; break;
  case 20: omcb |= 0x60; break;
  default: return -21;
  }

  if (periodicReset) omcb |= 0x10;

  switch(m)
  {
  case STANDBY: break;  // omcb |= 0x00;
  case QUERY: omcb |= 0x01; break;
  case CONT: omcb |= 0x02; break;
  default: return -20;
  }

  writeCmd(HMC_WRITE_RAM, 0x74, omcb);
  cmd(HMC_SAVE_OP_MODE);
  delayMicroseconds(125);
  return omcb;
}

// read the Operational Modus as byte from EEPROM
// TODO: split into 3 items
//
int hmc6352::getOperationalModus()
{
  // datasheet state that at startup the OM is copied from EEPROM
  // and that after writing to RAM a reboot is needed to enable new settings
  // my interpretation ==> EEPROM is leading
  return readCmd(HMC_READ_RAM, 0x74);
  //return readCmd(HMC_READ_EEPROM, 0x08);
}

// Switch between normal heading and raw modes
// default = 0 ==> normal headings
// Note: after a reboot the output modus will be 0 again.
int hmc6352::setOutputModus(uint8_t om)
{
  if (om > 4) return -20;
  return writeCmd(HMC_WRITE_RAM, 0x4E, om);
}

// Read the output modus from RAM
int hmc6352::getOutputModus()
{
  return readCmd(HMC_READ_RAM, 0x4E);
}

// NOT TESTED
int hmc6352::callibrationOn()
{
  int rv = cmd(HMC_CALLIBRATE_ON);
  delayMicroseconds(10);
  return rv;
}

// NOT TESTED
int hmc6352::callibrationOff()
{
  int rv = cmd(HMC_CALLIBRATE_OFF);
  delay(15);
  return rv;
}

// NOT TESTED
int hmc6352::setI2CAddress(uint8_t address)
{
  if (address < 0x10 || address > 0xF6 ) return -20;
  return writeCmd(HMC_WRITE_EEPROM, 0, address);
}

// returns current I2C address
int hmc6352::getI2CAddress()
{
  return readCmd(HMC_READ_EEPROM, 0);
}

// NOT TESTED
// meaning time delay unknown
// therefore removed from lib for now
int hmc6352::setTimeDelay(uint8_t msec)
{
  return writeCmd(HMC_WRITE_EEPROM, 5, msec);
}

int hmc6352::getTimeDelay()
{
  return readCmd(HMC_READ_EEPROM, 5);
}

// NOT TESTED
// meaning measurement summing unknown
// therefore removed from lib for now
int hmc6352::setMeasurementSumming(uint8_t ms)
{
  if (ms > 16 ) ms = 16;
  return writeCmd(HMC_WRITE_EEPROM, 6, ms);
}

int hmc6352::getMeasurementSumming()
{
  return readCmd(HMC_READ_EEPROM, 6);
}

// Makes only sense in setOperationalModus()
// therefore removed from lib for now
int hmc6352::saveOpMode()
{
  int rv = cmd(HMC_SAVE_OP_MODE);
  delayMicroseconds(125);
  return rv;
}


// NOT TESTED
// meaning UpdateOffsets unknown
// therefore removed from lib for now
int hmc6352::updateOffsets()
{
  int rv = cmd(HMC_UPDATE_OFFSETS);
  delay(6);
  return rv;
}

// idem
// use at own risk ...
int hmc6352::writeEEPROM(uint8_t address, uint8_t data)
{
  return writeCmd(HMC_WRITE_EEPROM, address, data);
}

// idem
int hmc6352::readEEPROM(uint8_t address)
{
  return readCmd(HMC_READ_EEPROM, address);
}


// idem
// Most RAM locations have an unknown meaning
// use at own risk ...
int hmc6352::writeRAM(uint8_t address, uint8_t data)
{
  return writeCmd(HMC_WRITE_RAM, address, data);
}
// idem
int hmc6352::readRAM(uint8_t address)
{
  return readCmd(HMC_READ_RAM, address);
}

/* PRIVATE FUNCTIONS
  mostly to remove redundancy in functions above
*/
int hmc6352::cmd(uint8_t c)
{
  Wire.beginTransmission(_device);
  WIRE_WRITE(c);
  int rv = Wire.endTransmission();
  delay(10);
  return rv;
}

int hmc6352::readCmd(uint8_t c, uint8_t address)
{
  Wire.beginTransmission(_device);
  WIRE_WRITE(c);
  WIRE_WRITE(address);
  int rv = Wire.endTransmission();
  if (rv != 0) return -rv;

  delayMicroseconds(70);

  rv = Wire.requestFrom(_device, (uint8_t)1);
  if (rv != 1) return -10;
  rv = WIRE_READ();
  return rv;
}

int hmc6352::writeCmd(uint8_t c, uint8_t address, uint8_t data)
{
  Wire.beginTransmission(_device);
  WIRE_WRITE(c);
  WIRE_WRITE(address);
  WIRE_WRITE(data);
  int rv = Wire.endTransmission();
  delayMicroseconds(70);
  return rv;
}