#include "common.h"
#include "bus/usart.h"
#include "bus/twi.h"

#include <avr/interrupt.h>
#include <assert.h>

// ADS1115 (ADC)
// PCA9546 (Multiplexer TWI)
// ATH20 (3x)
// BMP280 (3x)

// PB0 Mosfet 1 Peltier
// PB1 Mosfet 2 Heating
// PB2 Mosfet 3 Lights

// PD4 PWM Peltier Hot Side
// PD5 PWM Peltier Cold Side
// PD7 PWM Heating

// PC0 TWI Multiplexer SCL
// PC1 TWI Multiplexer SDA

// PD0 Serial USART RX
// PD1 Serial USART TX

static void SetPinDefaults(void);
static void SetTWIChannel(int channel);

int main(void)
{
	SetPinDefaults();

	USART_Init();
	TWI_Init();

	sei();

	Info("Initializing...");
	SetTWIChannel(0);

	Sleep(500);

	return 0;
}

static void SetPinDefaults(void)
{
	// Initialize Pin Outputs
	// ======================

	// PB0: MOSFET #1 (Peltier)
	DDRB |= (1 << PB0);    // Out
	PORTB &= ~(1 << PB0);  // Low

	// PB1: MOSFET #2 (Heating)
	DDRB |= (1 << PB1);    // Out
	PORTB &= ~(1 << PB1);  // Low

	// PB2: MOSFET #3 (Lights)
	DDRB |= (1 << PB2);    // Out
	PORTB &= ~(1 << PB2);  // Low
}

static void SetTWIChannel(int channel)
{
	unsigned char crb;

	assert(channel >= 0);
	assert(channel <= 3);

	// PCA9546 I2C Multiplexer
	// =======================

	Info("Switching TWI channel to %d...", channel);

	// Excerpts taken from the PCA9546A datasheet:
	// https://www.ti.com/lit/ds/symlink/pca9546a.pdf

	// Following a start condition, the bus master
	// must output the address of the slave it is
	// accessing.

	//  7  6  5  4   |   3   2   1   0
	//  1  1  1  0   |  A2  A1  A0  RW
	//  FIXED_____   |  SELECTABLE____

	TWI_Start(0x70, 0);
	TWI_Wait_ACK();

	// Following the successful acknowledgment of
	// the slave address, the bus master sends a byte
	// which is stored in the control register.

	//  7  6  5  4   |   3   2   1   0
	//  X  X  X  X   |  B3  B2  B1  B0
	//  UNUSED____   |  CHANNEL_______

	crb = (1 << channel);

	// crb = 0x01; //  Channel 0  |  00000001
	// crb = 0x02  //  Channel 1  |  00000010
	// crb = 0x04  //  Channel 2  |  00000100
	// crb = 0x08  //  Channel 3  |  00001000

	TWI_Write(crb);

	// When a channel is selected, the channel
	// becomes active after a stop condition has been
	// placed on the I2C bus. A stop condition always
	// must occur right after the acknowledge cycle.

	TWI_Wait_ACK();
	TWI_Stop();

	Info("TWI channel was switched to %d.", channel);
}