Implemented checksumming

Modem/cfg/cfg_debug.h

@@ -49,7 +49,7 @@
  * Baudrate for the debug console.
  * $WIZ$ type = "int"; min = 300
  */
-#define CONFIG_KDEBUG_BAUDRATE  115200UL
+#define CONFIG_KDEBUG_BAUDRATE  57600UL
 
 /**
  * Clock source for the UART module. You need to write the code to reprogram the respective clock at the required frequency in your project before calling kdbg_init().

Modem/config.h

@@ -7,7 +7,7 @@
 #define CONFIG_AFSK_DAC_SAMPLERATE 9600
 #define CONFIG_AFSK_RXTIMEOUT 0
 
-#define CONFIG_AFSK_PREAMBLE_LEN 300UL
-#define CONFIG_AFSK_TRAILER_LEN 50UL
+#define CONFIG_AFSK_PREAMBLE_LEN 500UL
+#define CONFIG_AFSK_TRAILER_LEN 100UL
 
 #endif

Modem/main.c

@@ -18,10 +18,14 @@ static MP1 mp1;
 
 #define ADC_CH 0
 
-#define TEST_PACKET "Test MP1 AFSK Packet!"
+#define TEST_PACKET "Test MP1 AFSK Packet! This one is longer and probably more prone to errors..."
+
+static uint8_t serialBuffer[MP1_MAX_FRAME_LENGTH];
+static int sbyte;
+static uint8_t serialLen = 0;
+static bool sertx = false;
 
 static void mp1Callback(struct MP1Packet *packet) {
-	kfile_printf(&ser.fd, "\nMP1 Packet Received:\n");
 	kfile_printf(&ser.fd, "%.*s\r\n", packet->dataLength, packet->data);
 }
 
@@ -29,29 +33,46 @@ static void init(void)
 {
 	IRQ_ENABLE;
 	kdbg_init();
+    kprintf("Init\n");
+
 	timer_init();
 
 	afsk_init(&afsk, ADC_CH, 0);
 	mp1Init(&mp1, &afsk.fd, mp1Callback);
 
-	
 	ser_init(&ser, SER_UART0);
-	ser_setbaudrate(&ser, 115200);
+	ser_setbaudrate(&ser, 57600);
+	//ser_settimeouts(&ser, 0, 0);
 }
 
 int main(void)
 {
 	init();
 	ticks_t start = timer_clock();
-
+	
 	while (1)
 	{
 		mp1Poll(&mp1);
 
+		sbyte = ser_getchar_nowait(&ser);
+		if (sbyte != EOF) {
+			if (serialLen < MP1_MAX_FRAME_LENGTH && sbyte != 138) {
+				serialBuffer[serialLen] = sbyte;
+				serialLen++;
+			} else {
+				sertx = true;
+			}
+		}
+
+		if (sertx) {
+			mp1Send(&mp1, serialBuffer, serialLen);
+			sertx = false;
+			serialLen = 0;
+		}
+
 		// Periodically send test data
-		if (timer_clock() - start > ms_to_ticks(4000L))
+		if (false && timer_clock() - start > ms_to_ticks(4000L))
 		{
-			kputs("Test TX\n");
 			start = timer_clock();
 			mp1Send(&mp1, TEST_PACKET, sizeof(TEST_PACKET));
 		}

Modem/protocol/mp1.c

@@ -1,12 +1,13 @@
 #include "mp1.h"
 #include <string.h>
+#include <drv/ser.h>
 //#include <ctype.h>
 
 static void mp1Decode(MP1 *mp1) {
 	MP1Packet packet;				// A decoded packet struct
 	uint8_t *buffer	= mp1->buffer;	// Get the buffer from the protocol context
 
-	packet.dataLength = mp1->packetLength;
+	packet.dataLength = mp1->packetLength - 1;
 	packet.data = buffer;
 
 	if (mp1->callback) mp1->callback(&packet);
@@ -25,12 +26,24 @@ void mp1Poll(MP1 *mp1) {
 				// frame length, which means the flag signifies
 				// the end of the packet. Pass control to the
 				// decoder.
-				mp1Decode(mp1);
+				kprintf("Got checksum: %d.\n", mp1->buffer[mp1->packetLength-1]);
+				if ((mp1->checksum_in & 0xff) == 0x00) {
+					//kprintf("Correct checksum. Found %d.\n", mp1->buffer[mp1->packetLength-1]);
+					mp1Decode(mp1);
+				} else {
+					// Checksum was incorrect
+					mp1Decode(mp1);
+					//kprintf("Incorrect checksum. Found %d.\n", mp1->buffer[mp1->packetLength]);
+					//kprintf("should be %d", mp1->checksum_in);
+				}
 			}
 			// If the above is not the case, this must be the
 			// beginning of a frame
 			mp1->reading = true;
 			mp1->packetLength = 0;
+			mp1->checksum_in = MP1_CHECKSUM_INIT;
+			//kprintf("Checksum init with %d\n", mp1->checksum_in);
+
 			// We have indicated that we are reading,
 			// and reset the length counter. Now we'll
 			// continue to the next byte.
@@ -59,6 +72,8 @@ void mp1Poll(MP1 *mp1) {
 				// If the length of the current incoming frame is
 				// still less than our max length, put the incoming
 				// byte in the buffer.
+				if (!mp1->escape) mp1->checksum_in = mp1->checksum_in ^ byte;
+				//kprintf("Checksum is now %d\n", mp1->checksum_in);
 				mp1->buffer[mp1->packetLength++] = byte;
 			} else {
 				// If not, we have a problem: The buffer has overrun
@@ -95,13 +110,25 @@ void mp1Send(MP1 *mp1, const void *_buffer, size_t length) {
 	// Get the transmit data buffer
 	const uint8_t *buffer = (const uint8_t *)_buffer;
 
+	// Initialize checksum
+	mp1->checksum_out = MP1_CHECKSUM_INIT;
+	//kprintf("Checksum init with %d\n", mp1->checksum_out);
+
 	// Transmit the HDLC_FLAG to signify start of TX
 	kfile_putc(HDLC_FLAG, mp1->modem);
 
 	// Continously increment the pointer address
 	// of the buffer while passing it to the byte
 	// output function
-	while (length--) mp1Putbyte(mp1, *buffer++);
+	while (length--) {
+		mp1->checksum_out = mp1->checksum_out ^ *buffer;
+		//kprintf("Checksum is now %d\n", mp1->checksum_out);
+		mp1Putbyte(mp1, *buffer++);
+	}
+
+	// Write checksum to end of packet
+	kprintf("Checksum of this packet is %d\n", mp1->checksum_out);
+	mp1Putbyte(mp1, mp1->checksum_out);
 
 	// Transmit a HDLC_FLAG to signify end of TX
 	kfile_putc(HDLC_FLAG, mp1->modem);

Modem/protocol/mp1.h

@@ -4,9 +4,10 @@
 #include <cfg/compiler.h>
 #include <io/kfile.h>
 
-// Frame sizing
-#define MP1_MIN_FRAME_LENGTH 1
+// Frame sizing & checksum
+#define MP1_MIN_FRAME_LENGTH 3
 #define MP1_MAX_FRAME_LENGTH 300
+#define MP1_CHECKSUM_INIT 0xAA
 
 // We need to know some basic HDLC flag bytes
 #define HDLC_FLAG  0x7E
@@ -26,6 +27,8 @@ typedef struct MP1 {
 	KFile *modem;							// KFile access to the modem
 	size_t packetLength;					// Counter for received packet length
 	mp1_callback_t callback;				// The function to call when a packet has been received
+	uint8_t checksum_in;					// Rolling checksum for incoming packets
+	uint8_t checksum_out;					// Rolling checksum for outgoing packets
 	bool reading;							// True when we have seen a HDLC flag
 	bool escape;							// We need to know if we are in an escape sequence
 } MP1;

buildrev.h

@@ -1,2 +1,2 @@
-#define VERS_BUILD 148
+#define VERS_BUILD 308
 #define VERS_HOST  "vixen"