atmega-simon/main.c

#include <avr/io.h>          // register definitions
#include <avr/pgmspace.h>    // storing data in program memory
#include <avr/interrupt.h>   // interrupt vectors
#include <util/delay.h>      // delay functions

#include <stdint.h>          // C header for int types like uint8_t
#include <stdbool.h>         // C header for the bool type

// Include stuff from the library
#include "lib/iopins.h"
#include "lib/usart.h"
#include "lib/spi.h"
#include "lib/adc.h"

#include "pinout.h"

void setup_io(void)
{
	as_output(PIN_DISP_CP);
	as_output(PIN_DISP_D);
	as_output(PIN_DISP_STR);

	as_input(PIN_KEY_1);
	as_input(PIN_KEY_2);
	as_input(PIN_KEY_3);
	as_input(PIN_KEY_4);

	as_output(PIN_NEOPIXEL);
	as_output(PIN_DISP_OE);

	as_input(PIN_PWR_KEY);
	as_output(PIN_PWR_HOLD);

	// PIN_LIGHT_SENSE is ADC exclusive, needs no config
}

// --- LED display brightness control ---
#define DISP_BRIGHTNESS OCR2B
void setup_pwm(void)
{
	// PWM for LED display dimming
	TCCR2A |= (1 << WGM20) | (1 << WGM21) | (1 << COM2B1);
	TCCR2B |= (1 << CS20);

	DISP_BRIGHTNESS = 0x7F;
}

void main()
{
	usart_init(BAUD_115200);
	usart_isr_rx_enable(true); // enable RX interrupt handler

	setup_io();
	setup_pwm();
	adc_init(ADC_PRESC_128);

	// SPI conf
	spi_init_master(SPI_LSB_FIRST,
					CPOL_1, CPHA_0,
					SPI_DIV_2);

	// globally enable interrupts
	sei();

	uint8_t cnt = 0;

	while (1) {
		pin_down(PIN_DISP_STR);
		spi_send(cnt);
		spi_send(cnt);
		pin_up(PIN_DISP_STR);
		cnt++;

		_delay_ms(100);

		// Brightness directly proportional to light level
		DISP_BRIGHTNESS = 255 - adc_read_byte(6);
	}
}

// UART receive handler
ISR(USART_RX_vect)
{
	// "ECHO" function:
	uint8_t b = usart_rx();
	usart_tx(b); // send back
}