mixer-slider/firmware/slider/main.c

#include <avr/io.h>
#include <avr/interrupt.h>
#include "adc.h"
#include "led.h"
#include "button.h"
#include "main.h"

/* Communication driver */
#define SLAVE_ENABLE_DDR DDRA
#define SLAVE_ENABLE_REG PINA
#define SLAVE_ENABLE_PIN 1

#include <interface.h>

typedef struct {
	byte_t * buffer_start, * buffer_end;
	
	volatile byte_t * read;
	volatile byte_t * write;
	volatile byte_t count; 
	
	iface_t iface;
} comm_t;

comm_t comm;

void comm_write(iface_t * iface, byte_t byte) {
	if ((comm.write == comm.read) && comm.count) {
		// write overflow
		return;
	}
	
	*comm.write = byte;
	++comm.count;
	
	// advance write pointer
	if ((++comm.write) >= comm.buffer_end) {
		comm.write = comm.buffer_start;
	}
}

inline byte_t comm_read() {
	if (!comm.count)
		return 0x00;
		
	byte_t result = *comm.read;
	
	--comm.count;
	if ((++comm.read) >= comm.buffer_end) {
		comm.read = comm.buffer_start;
	}
	
	return result;
}

byte_t comm_buffer[10];

void comm_init() 
{
	comm.buffer_start = comm_buffer;
	comm.buffer_end   = comm_buffer + sizeof(comm_buffer);
	
	// reset buffer
	comm.write = comm.buffer_start;
	comm.read  = comm.buffer_start;
	comm.count = 0;
	
	// TODO: setup pins
	DDRA |= (1<<PA5); // setup MOSI as output
	
	// TODO: setup USART in synchronous mode
	USICR = (1<<USIWM0)|(1<<USICS1);

	// init interface
	comm.iface.write   = comm_write;
	comm.iface.on_read = 0;
}

void comm_start() 
{
	// don't start without interrupt handler
	if (!comm.iface.on_read)
		return;

	// TODO: activate USART 
	USICR |= (1<<USIOIE);
}

ISR(USI_OVF_vect) 
{
	cli();
	// write buffer out if there is data to be written
	//if (!comm.count) {
		// call interrupt handler
		//comm.iface.on_read(&comm.iface, USIDR, comm.iface.callback_data);
	//}
	
	USIDR = 0x02;
	sei();
	//USIDR = comm_read();
}

#include "main.h"

// the public instance of the app buffer
struct app app = {};

adc_sample_t * channel_map[] = {
	// update app state (remap channels)
	&app.state.state.poti[2],
	&app.state.state.poti[3],
	&app.state.state.poti[1],
	&app.state.state.poti[0],
	&app.state.state.slider
};

// initalizes the application modules
void init() 
{
	// init button module (making the button light up on press)
	// module also updates app.buffer.button for us
	button_init();

	// init adc module
	// will sample 0x8F (CHANNEL 8 and 0-3) 
	// this module also updates app.buffer.poti and slider for us
	adc_init((adc_buffer_t){
		.ptr  = channel_map,
		.size = sizeof(channel_map),
	}, 0x8F);

	// init communication module
	comm_init();
	
	// bind state encoder to communication module
	slave_init(&app.state, &comm.iface);
	
	// start all modules
	adc_start();
	comm_start();
	
	// activate interrupts (effectivly starting the application)
	sei();
}

#include <util/delay.h>

// little debug helper function
// FIXME: remove when not needed
void delay(uint16_t d) 
{
	while(d--) 
	{
		_delay_ms(1);
	}
}

int main() 
{
	init();
	
	while(1) {
		// nothing to do here, the application is interrupt-driven
	}
}