i2cControl.swift

let storedBrightnessLocation: UInt16 = 34
let storedOnOffLocation: UInt16 = 35
let brightnessi2cRegister = 6
let onOffi2cRegister = 7

// defaults until EEPROM is read
var delayFactor = 90
var delayUs: UInt32 = 9000
var enabled = false

func i2cUpdate(register: UInt8, value: UInt8) {
  if register == brightnessi2cRegister {
    updateDelay(value)
  } else if register == onOffi2cRegister {
    updateEnabled(boolForUInt8(value))
  }
}

func i2cRead(register: UInt8) -> UInt8 {
  if register == brightnessi2cRegister {
    return delayFactor
  } else if register == onOffi2cRegister {
    return uint8ForBool(enabled)
  }

  return 0
}

// the update function, calcs and storage
func updateDelay(_ newDelayFactorIn: UInt8) {
  var newDelayFactor = newDelayFactorIn

  if newDelayFactor > 90 {
    newDelayFactor = 90
  }

  if newDelayFactor < 5 {
    newDelayFactor = 5
  }

  delayFactor = newDelayFactor

  delayUs = UInt32(newDelayFactor) &* 100

  writeEEPROM(address: storedBrightnessLocation, value: newDelayFactor)
}

func updateEnabled(_ newEnabled: Bool) {
  enabled = newEnabled
  writeEEPROM(address: storedOnOffLocation, value: uint8ForBool(newEnabled))
}


// initialise brightness from EEPROM
updateDelay(readEEPROM(address: storedBrightnessLocation))
enabled = boolForUInt8(readEEPROM(address: storedOnOffLocation))

// Use I2C to communicate to the pi for remote control
i2cSlaveSetupRegisterReceiveCallback { register, value in
  i2cUpdate(register: register, value: value)
}

i2cSlaveSetupRegisterSendCallback { register -> UInt8 in
  return i2cRead(register: register)
}

setupI2CSlave(address: 0x23)