Added Timeouts (untested)

software/AVR8/Makefile

@@ -4,8 +4,8 @@ ISPPORT ?= /dev/kaboard
 
 VERSION = 0.1
 
-HEADERS = sss7.h uart.h
-SRC = main.c sss7.c uart.c
+HEADERS = sss7.h uart.h timer.h
+SRC = main.c sss7.c uart.c timer.c
 TARGET = sss7
 OBJDIR = bin
 

software/AVR8/sss7.c

@@ -18,6 +18,8 @@ volatile uint8_t sss7_tx_failed;
 uint8_t sss7_tx_last_byte;
 uint8_t sss7_tx_last_ack;
 
+volatile uint8_t sss7_timeout_counter;
+
 
 void sss7_init(void) {
 	sss7_state = SSS7_IDLE;
@@ -29,9 +31,6 @@ void sss7_init(void) {
 	sss7_tx_pos = 0;
 	sss7_tx_crc = 0;
 	sss7_tx_failed = 0;
-
-	DDRB |= (1 << PB2)| (1 << PB3);
-	PORTB |= (1 << PB2) | (1 << PB3);
 }
 
 
@@ -50,7 +49,7 @@ static inline uint8_t sss7_payload_crc(uint8_t buffer[SSS7_PAYLOAD_SIZE]) {
 			}
 		}
 	}
-	
+
 	return crc;
 }
 
@@ -77,6 +76,7 @@ void sss7_send(uint8_t msg[SSS7_PAYLOAD_SIZE]) {
 	// Commit to send state
 	sss7_state = SSS7_TX_HEADER;
 	sss7_tx_failed = 0;
+	sss7_timeout_counter = 0;
 	sss7_send_byte(SSS7_HEADER[0]);
 }
 
@@ -84,12 +84,12 @@ void sss7_send(uint8_t msg[SSS7_PAYLOAD_SIZE]) {
 void sss7_process_rx(void) {
 	uint8_t byte = uart_get_byte();
 	uint8_t crc = 0;
+	sss7_timeout_counter = 0;
 
 	switch(sss7_state) {
 		case SSS7_IDLE:
 			if(byte == SSS7_HEADER[0]) {
 				sss7_state = SSS7_RX_HEADER;
-				PORTB |= (1 << PB3);
 			}
 			else {
 				sss7_state = SSS7_IDLE;
@@ -119,7 +119,6 @@ void sss7_process_rx(void) {
 			if(byte == crc) {
 				sss7_rx_active_buffer = (sss7_rx_active_buffer + 1) % SSS7_RX_BUFFER_COUNT;
 			}
-			PORTB &= ~(1 << PB3);
 			sss7_state = SSS7_IDLE;
 		break;
 
@@ -172,6 +171,23 @@ void sss7_process_tx(void) {
 	}
 }
 
+void sss7_process_ticks(uint16_t ticks) {
+	if(sss7_state != SSS7_IDLE) {
+		sss7_timeout_counter = sss7_timeout_counter + ticks;
+
+		if(sss7_timeout_counter > sss7_timeout) {
+			switch(sss7_state) {
+				case SSS7_TX_HEADER:
+				case SSS7_TX_PAYLOAD:
+				case SSS7_TX_CRC:
+					sss7_tx_failed = 1;
+				default:
+					sss7_state = SSS7_IDLE;
+			}
+		}
+	}
+}
+
 
 void sss7_get_received(uint8_t msg[SSS7_PAYLOAD_SIZE]) {
 	if(sss7_has_received()) {

software/AVR8/sss7.h

@@ -15,10 +15,13 @@ enum sss7State {
 };
 
 const static uint8_t SSS7_HEADER[] = {0xAA, 0xFE};
+const static uint16_t sss7_timeout = 50;
+const static uint16_t sss7_timeout_increment = 1;
 
 #define SSS7_PAYLOAD_SIZE 16
 #define SSS7_RX_BUFFER_COUNT 2
 
+
 extern volatile enum sss7State sss7_state;
 extern volatile uint8_t sss7_tx_failed;
 extern uint8_t sss7_rx_active_buffer;
@@ -26,6 +29,7 @@ extern uint8_t sss7_rx_oldest_buffer;
 
 void sss7_process_rx(void);
 void sss7_process_tx(void);
+void sss7_process_ticks(uint16_t ticks);
 
 
 void sss7_init(void);

software/AVR8/timer.c

@@ -0,0 +1,28 @@
+#include "timer.h"
+
+#include <avr/interrupt.h>
+#include <avr/io.h>
+
+#include "sss7.h"
+
+/*
+* Timer setting:
+* MCU running at 16MHz:
+* Prescaler is 64 which results in 250000 ticks per second
+* Preloading the counter with 6 leads to 1000 overflow interrupts per second
+* or one overflow every millisecond.
+*/
+
+void timer_init(void) {
+	TCNT0 = 6;	//Preload for 250 ticks to overflow
+	TIMSK |= (1 << TOIE0);
+	TCCR0 = (1 << CS00) | (1 << CS01);	// Prescaler 64
+}
+
+
+
+ISR(TIMER0_OVF_vect) {
+	TCNT0 = 6; //Preload for 250 ticks to overflow
+
+	sss7_process_ticks(sss7_timeout_increment);
+}

software/AVR8/timer.h

@@ -0,0 +1,7 @@
+#ifndef _TIMER_H_
+#define _TIMER_H_
+
+void timer_init(void);
+
+
+#endif