OpenModem/Modem/main.c

//////////////////////////////////////////////////////
// First things first, all the includes we need     //
//////////////////////////////////////////////////////

#include <cpu/irq.h>		// Interrupt functionality from BertOS
#include "cfg/debug.h"		// Debug configuration from BertOS

#include <drv/ser.h>		// Serial driver from BertOS
#include <drv/timer.h>		// Timer driver from BertOS

#include <stdio.h>			// Standard input/output
#include <string.h>			// String operations

#include "afsk.h"			// Header for AFSK modem
#include "protocol/mp1.h"	// Header for MP.1 protocol


//////////////////////////////////////////////////////
// A few definitions				                //
//////////////////////////////////////////////////////

static Afsk afsk;			// Declare a AFSK modem struct
static MP1 mp1;				// Declare a protocol struct
static Serial ser;			// Declare a serial interface struct

#define ADC_CH 0			// Define which channel (pin) we want
							// for the ADC (this is A0 on arduino)


static uint8_t serialBuffer[MP1_MAX_DATA_SIZE];	// This is a buffer for incoming serial data

static int sbyte;									// For holding byte read from serial port
static size_t serialLen = 0;						// Counter for counting length of data from serial
static bool sertx = false;							// Flag signifying whether it's time to send data
													// Received on the serial port.

//////////////////////////////////////////////////////
// And here comes the actual program :)             //
//////////////////////////////////////////////////////

// This is a callback we register with the protocol,
// so we can process each packet as they are decoded.
// Right now it just prints the packet to the serial port.
static void mp1Callback(struct MP1Packet *packet) {
	if (SERIAL_DEBUG) {
		kfile_printf(&ser.fd, "%.*s\n", packet->dataLength, packet->data);
	} else {
		for (unsigned long i = 0; i < packet->dataLength; i++) {
			kfile_putc(packet->data[i], &ser.fd);
		}
	}
}

// Simple initialization function.
static void init(void)
{
	// Enable interrupts
	IRQ_ENABLE;

    // Initialize hardware timers
	timer_init();

	// Initialize serial comms on UART0,
	// which is the hardware serial on arduino
	ser_init(&ser, SER_UART0);
	ser_setbaudrate(&ser, 9600);

	// For some reason BertOS sets the serial
	// to 7 bit characters by default. We set
	// it to 8 instead.
	UCSR0C = _BV(UCSZ01) | _BV(UCSZ00);

	// Create a modem context
	afsk_init(&afsk, ADC_CH);
	// ... and a protocol context with the modem
	mp1Init(&mp1, &afsk.fd, mp1Callback);

	// That's all!
}

int main(void)
{
	// Start by running the main initialization
	init();
	// Record the current tick count for time-keeping
	ticks_t start = timer_clock();
	
	// Go into ye good ol' infinite loop
	while (1)
	{	
		// First we instruct the protocol to check for
		// incoming data
		mp1Poll(&mp1);

		
		// If there was actually some data waiting for us
		// there, let's se what it tastes like :)
		if (ser_available(&ser)) {
			// We then read a byte from the serial port.
			// Notice that we use "_nowait" since we can't
			// have this blocking execution until a byte
			// comes in.
			sbyte = ser_getchar_nowait(&ser);

			// If SERIAL_DEBUG is specified we'll handle
			// serial data as direct human input and only
			// transmit when we get a LF character
			if (SERIAL_DEBUG) {
				// If we have not yet surpassed the maximum frame length
				// and the byte is not a "transmit" (newline) character,
				// we should store it for transmission.
				if ((serialLen < MP1_MAX_DATA_SIZE) && (sbyte != 10)) {
					// Put the read byte into the buffer;
					serialBuffer[serialLen] = sbyte;
					// Increment the read length counter
					serialLen++;
				} else {
					// If one of the above conditions were actually the
					// case, it means we have to transmit, se we set
					// transmission flag to true.
					sertx = true;
				}
			} else {
				// Otherwise we assume the modem is running
				// in automated mode, and we push out data
				// as it becomes available. We either transmit
				// immediately when the max frame length has
				// been reached, or when we get no input for
				// a certain amount of time.

				if (serialLen < MP1_MAX_DATA_SIZE-1) {
					// Put the read byte into the buffer;
					serialBuffer[serialLen] = sbyte;
					// Increment the read length counter
					serialLen++;
				} else {
					// If max frame length has been reached
					// we need to transmit.
					serialBuffer[serialLen] = sbyte;
					serialLen++;
					sertx = true;
				}

				start = timer_clock();
			}
		} else {
			if (!SERIAL_DEBUG && serialLen > 0 && timer_clock() - start > ms_to_ticks(TX_MAXWAIT)) {
				sertx = true;
			}
		}

		// Check whether we should send data in our serial buffer
		if (sertx) {	
			// Wait until incoming packets are done
			if (!mp1CarrierSense(&mp1)) {
				// And then send the data
				mp1Send(&mp1, serialBuffer, serialLen);
				
				// Reset the transmission flag and length counter
				sertx = false;
				serialLen = 0;
			}
		}
	}
	return 0;
}