/*
 * HtM_Sensors.c
 *
 * Created: 11/21/2017 9:11:11
 * Author : Casey Evans
 */ 

/* Original template from the Tinysaur project */
/* Adapted basic functional code from Neil's code */

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

// ====================================
//                ATtiny
//                 44A
//              +--------+
//            --+Vcc  GND+---------
//  LED - PB0 --+        +-- PA0
//  LED - PB1 --+        +-- PA1
//  LED - PB3 --+        +-- PA2
//  LED - PB2 --+        +-- PA3
//  LED - PA7 --+        +-- PA4
//  LED - PA6 --+        +-- PA5
//              +--------+
// ====================================

// Define the I/O port to be used for the sensors.
// The sensors each use one or two ports and I will define them accordingly.
// That way they will line up properly on the headers.
#define LED_PORT PA7
#define BUTTON_PORT PB2
#define SERIAL_PORT PA1
#define SENSE1 PA2
#define SENSE2 PA3
#define BUTTON_IN (1 << PB2)
#define nsamples 100 // number of samples to accumulate

int main(void) {
	
	// Set ports as outputs
	// The DDRA/B is the data direction register
	// The code below
	//  - shifts the "1" on left to the desired position
	//  - does bitwise "OR" with the value in the port register.
	DDRA |= (1 << LED_PORT);
	PORTA |= (1 << SERIAL_PORT);
	DDRA |= (1 << SERIAL_PORT);
	// Good practice to leave these as outputs until we need them
	DDRA |= (1 << SENSE1);
	DDRA |= (1 << SENSE2);
	// Sets port as input
	DDRB &= ~(1 << BUTTON_PORT);
	// Engages pull-up resistor
	PORTB |= (1 << BUTTON_PORT);
	
	// variables (from Neil's code)
	static uint16_t count;
	static uint32_t accum;

	// set clock divider to /1 (from Neil's code)
	CLKPR = (1 << CLKPCE);
	CLKPR = (0 << CLKPS3) | (0 << CLKPS2) | (0 << CLKPS1) | (0 << CLKPS0);
	
	// Magnetic sensor init A/D (from Neil's code)
	ADMUX = (0 << REFS1) | (0 << REFS0) // Vcc ref
	| (1 << ADLAR) // left adjust
	| (0 << MUX5) | (0 << MUX4) | (0 << MUX3) | (0 << MUX2) | (1 << MUX1) | (0 << MUX0); // ADC2
	ADCSRA = (1 << ADEN) // enable
	| (1 << ADPS2) | (1 << ADPS1) | (1 << ADPS0); // prescaler /128 
	
	// Put char from Neil's code
	void put_char(volatile unsigned char *port, unsigned char pin, char txchar) {
		// send character in txchar on port pin
		//    assumes line driver (inverts bits)
		// start bit
		*port &= (~pin);
		_delay_us(102);
		// unrolled loop to write data bits
		if (txchar & (1 << 0))
		*port |= pin;
		else
		*port &= (~pin);
		_delay_us(102);
		if (txchar & (1 << 1))
		*port |= pin;
		else
		*port &= (~pin);
		_delay_us(102);
		if (txchar & (1 << 2))
		*port |= pin;
		else
		*port &= (~pin);
		_delay_us(102);
		if (txchar & (1 << 3))
		*port |= pin;
		else
		*port &= (~pin);
		_delay_us(102);
		if (txchar & (1 << 4))
		*port |= pin;
		else
		*port &= (~pin);
		_delay_us(102);
		if (txchar & (1 << 5))
		*port |= pin;
		else
		*port &= (~pin);
		_delay_us(102);
		if (txchar & (1 << 6))
		*port |= pin;
		else
		*port &= (~pin);
		_delay_us(102);
		if (txchar & (1 << 7))
		*port |= pin;
		else
		*port &= (~pin);
		_delay_us(102);
		// stop bit
		*port |= pin;
		_delay_us(102);
		// char delay
		_delay_us(102);
	}
	
	while (1) {
		
		// accumulate samples
		accum = 0;
		for (count = 0; count < nsamples; ++count) {
			// initiate conversion
			ADCSRA |= (1 << ADSC);
			// wait for completion
			while (ADCSRA & (1 << ADSC))
			;
			// add result
			accum += ADC;
		}
		
		// send framing
		put_char(&PORTA, (1 << SERIAL_PORT), 1);
		_delay_ms(10);
		put_char(&PORTA, (1 << SERIAL_PORT), 2);
		_delay_ms(10);
		put_char(&PORTA, (1 << SERIAL_PORT), 3);
		_delay_ms(10);
		put_char(&PORTA, (1 << SERIAL_PORT), 4);
		_delay_ms(10);
		// send result
		put_char(&PORTA, (1 << SERIAL_PORT), (accum & 255));
		_delay_ms(10);
		put_char(&PORTA, (1 << SERIAL_PORT), ((accum >> 8) & 255));
		_delay_ms(10);
		put_char(&PORTA, (1 << SERIAL_PORT), ((accum >> 16) & 255));
		_delay_ms(10);
		
	}
	return (0);
}