Fixed rx buffer behaviour

Fixed bytes being swapped in error message

README.md

@@ -81,9 +81,11 @@ Initial value: 0x0
     the frame is considered timed out and all received data can be dropped.
 - Incoming messages are stored in a fifo until the application retrieves them.
 - The receive fifo has a size of at least 2 messages.
-- If the fifo is full new messages will be dropped, until the application retrieves a message.
+- If the fifo is full new messages will override the older ones.
+    It is up to the application retrieve message in time.
 - Even if sending was successful, there is still a chance that the receiver could not
-    receive the frame due to missing buffer space or not enough processing time to react. **Important messages should utilize a ack-mechanism.**
+    receive the frame due to missing buffer space or not enough processing time to react.
+    **Important messages should utilize a ack-mechanism.**
 - It is up to the application to resend messages in case of a collision/missing ack.
 
 ### Planned API

software/AVR8/Makefile

@@ -1,6 +1,6 @@
 AVRMCU ?= atmega8
 F_CPU ?= 16000000
-ISPPORT ?= /dev/ttyUSB0
+ISPPORT ?= /dev/kaboard
 
 VERSION = 0.1
 

software/AVR8/main.c

@@ -33,15 +33,14 @@ sei();
 
 while(1) {
 
-    if(sss7_can_send()) {
+    while(!sss7_can_send());
-        sss7_send(msg);
+    sss7_send(msg);
-    }
     while(!sss7_can_send());
     if(sss7_send_failed()) {
         PORTB ^= (1 << PB2);
     }
 
-    _delay_ms(250);
+    _delay_ms(100);
 }
 
 

software/AVR8/sss7.c

@@ -6,7 +6,7 @@
 
 volatile enum sss7State sss7_state;
 
-uint8_t sss7_rx_buffer[2][SSS7_PAYLOAD_SIZE];
+uint8_t sss7_rx_buffer[SSS7_RX_BUFFER_COUNT][SSS7_PAYLOAD_SIZE];
 uint8_t sss7_rx_active_buffer;
 uint8_t sss7_rx_oldest_buffer;
 uint8_t sss7_rx_pos;
@@ -14,7 +14,7 @@ uint8_t sss7_rx_pos;
 uint8_t sss7_tx_buffer[SSS7_PAYLOAD_SIZE];
 uint8_t sss7_tx_pos;
 uint8_t sss7_tx_crc;
-uint8_t sss7_tx_failed;
+volatile uint8_t sss7_tx_failed;
 uint8_t sss7_tx_last_byte;
 uint8_t sss7_tx_last_ack;
 
@@ -74,6 +74,7 @@ ISR(USART_RXC_vect) {
 		case SSS7_IDLE:
 			if(byte == SSS7_HEADER[0]) {
 				sss7_state = SSS7_RX_HEADER;
+				PORTB |= (1 << PB3);
 			}
 			else {
 				sss7_state = SSS7_IDLE;
@@ -101,8 +102,9 @@ ISR(USART_RXC_vect) {
 		case SSS7_RX_CRC:
 			crc = sss7_payload_crc(sss7_rx_buffer[sss7_rx_active_buffer]);
 			if(byte == crc) {
-				sss7_rx_active_buffer = (sss7_rx_active_buffer + 1);
+				sss7_rx_active_buffer = (sss7_rx_active_buffer + 1) % SSS7_RX_BUFFER_COUNT;
 			}
+			PORTB &= ~(1 << PB3);
 			sss7_state = SSS7_IDLE;
 		break;
 
@@ -144,6 +146,9 @@ ISR(USART_TXC_vect) {
 				sss7_send_byte(sss7_tx_crc);
 				sss7_state = SSS7_IDLE;
 			break;
+
+			default:
+			break;
 		}
 	}
 	else {
@@ -156,6 +161,6 @@ ISR(USART_TXC_vect) {
 void sss7_get_received(uint8_t msg[SSS7_PAYLOAD_SIZE]) {
 	if(sss7_has_received()) {
 		memcpy(msg, sss7_rx_buffer[sss7_rx_oldest_buffer], SSS7_PAYLOAD_SIZE);
-		sss7_rx_oldest_buffer++;
+		sss7_rx_oldest_buffer = (sss7_rx_oldest_buffer + 1) % SSS7_RX_BUFFER_COUNT;
 	};
 }

software/AVR8/sss7.h

@@ -20,7 +20,7 @@ const static uint8_t SSS7_HEADER[] = {0xAA, 0xFE};
 #define SSS7_RX_BUFFER_COUNT 2
 
 extern volatile enum sss7State sss7_state;
-extern uint8_t sss7_tx_failed;
+extern volatile uint8_t sss7_tx_failed;
 extern uint8_t sss7_rx_active_buffer;
 extern uint8_t sss7_rx_oldest_buffer;
 
@@ -33,7 +33,7 @@ static inline uint8_t sss7_can_send(void) {
 void sss7_send(uint8_t msg[SSS7_PAYLOAD_SIZE]);
 
 static inline uint8_t sss7_send_failed(void) {
-	return sss7_state == SSS7_IDLE && sss7_tx_failed;
+	return sss7_tx_failed;
 }
 
 static inline uint8_t sss7_has_received(void) {

software/testutils/send.py

@@ -10,7 +10,7 @@ def send_byte(ser, byte):
     ser.write(byte)
     read_byte = ser.read()
     if read_byte != byte:
-        print "Written %s read %s" % (hex(ord(read_byte)), hex(ord(byte)))
+        print "Written %s read %s" % (hex(ord(byte)), hex(ord(read_byte)))
         sys.exit(-1)