#include <avr/io.h>
#include <util/delay.h>

#include "aht20.h"
#include "i2c.h"
#include "uart.h"

void aht20_print_status(uint8_t status) {
	uart_sendstring("AHT20: ");
	uart_sendstring((status & BV(3)) ? "Calibrated" : "Not Calibrated");
	uart_sendstring(";");
	uart_sendstring((status & BV(7)) ? "Busy" : "Not Busy");
	uart_sendstring(";\r\n");
}

// https://datasheet4u.com/pdf/1551700/AHT20.pdf

void aht20_init(void) {
	// we need to wait a bit after the poweron of the AHT20 device
	_delay_ms(40);

	i2c_start();
	i2c_write(I2C_ADDR(AHT20, TW_WRITE));
	i2c_write(0xBE);
	i2c_stop();

	//_delay_ms(10);
}

void aht20_trigger(void) {
	i2c_start();
	i2c_write(I2C_ADDR(AHT20, TW_WRITE));
	// trigger measurement command (7.4)
	i2c_write(0xAC);
	i2c_write(0x33);
	i2c_write(0x00);
	i2c_stop();
}

aht20_reading aht20_read_measure(void) {
	uint8_t data[6];

	i2c_start();
	i2c_write(I2C_ADDR(AHT20, TW_READ));

	for (uint8_t i = 0; i < 5; i++)
		data[i] = i2c_read_ack();

	data[5] = i2c_read_nack();
	// we dont read the checksum

	i2c_stop();

	uint32_t raw_humi = 0;
	uint32_t raw_temp = 0;

	struct aht20_reading out;

	raw_humi		= data[1];
	raw_humi	  <<= 8;
	raw_humi	   += data[2];
	raw_humi	  <<= 4;
	raw_humi	   += data[3] >> 4;

	out.humidity	= (float)raw_humi / 1048576.0;

	raw_temp		= data[3] & 0x0f;
	raw_temp	  <<= 8;
	raw_temp	   += data[4];
	raw_temp	  <<= 8;
	raw_temp	   += data[5];

	out.temperature = (float)raw_temp / 1048576.0 * 200.0 - 50.0;

	return out;
}

uint8_t aht20_status(void) {
	i2c_start();
	i2c_write(I2C_ADDR(AHT20, TW_READ));
	uint8_t status = i2c_read_nack();
	i2c_stop();

	return status & (BV(7) | BV(3));
}