i2c/hardware.hpp

#pragma once

#include <stdint.h>

#include <util/twi.h>

namespace i2c {

#if defined(__AVR_ATmega1284P__) || defined(__AVR_ATmega328P__)

enum class Prescaler {
	PRESCALER_1 = 0b00,
	PRESCALER_4 = 0b01,
	PRESCALER_16 = 0b10,
	PRESCALER_64 = 0b11,
};

template <Prescaler Pres, uint32_t Clock>
class Hardware {
  public:
	static void init()
	{
		TWSR = static_cast<uint8_t>(Pres);
		TWBR = calcClock();
	}

	template <uint8_t Addr>
	static bool start(bool read)
	{
		TWCR = (1 << TWINT) | (1 << TWSTA) | (1 << TWEN);
		while (!(TWCR & (1 << TWINT)))
			;

		uint8_t status = TW_STATUS & 0xF8;
		if (status != TW_START && status != TW_REP_START)
			return false;

		TWDR = (Addr << 1) | read;
		TWCR = (1 << TWINT) | (1 << TWEN);

		while (!(TWCR & (1 << TWINT)))
			;

		status = TW_STATUS & 0xF8;
		if (status != TW_MT_SLA_ACK && status != TW_MR_SLA_ACK)
			return false;

		return true;
	}

	static bool write(uint8_t data)
	{
		TWDR = data;
		TWCR = (1 << TWINT) | (1 << TWEN);

		while (!(TWCR & (1 << TWINT)))
			;

		uint8_t status = TW_STATUS & 0xF8;
		if (status != TW_MT_DATA_ACK)
			return false;

		return true;
	}

	template <bool LastByte = false>
	static uint8_t read()
	{
		TWCR = (1 << TWINT) | (1 << TWEN) | (!LastByte << TWEA);
		while (!(TWCR & (1 << TWINT)))
			;

		return TWDR;
	}

	static void stop()
	{
		TWCR = (1 << TWINT) | (1 << TWEN) | (1 << TWSTO);

		while (TWCR & (1 << TWSTO))
			;
	}

  private:
	static constexpr uint8_t calcClock()
	{
		return ((F_CPU / Clock) - 16) / 2;
	}
};

#endif

} // namespace i2c