Asynchronous IO implemented, packet queueing implemented

device.h

@@ -23,6 +23,7 @@
 #define CONFIG_QUEUE_SIZE 7500
 #define CONFIG_QUEUE_MAX_LENGTH 15
 #define CONFIG_SERIAL_BUFFER_SIZE 1532 // TODO: Tune this, what is actually required?
+#define CONFIG_SERIAL_TIMEOUT_MS 10
 
 // CSMA Settings
 #define CONFIG_FULL_DUPLEX false  // TODO: Actually implement fdx

hardware/AFSK.c

@@ -149,14 +149,6 @@ int afsk_getchar(FILE *stream) {
     }
 }
 
-void AFSK_transmit(char *buffer, size_t size) {
-    fifo_flush(&AFSK_modem->txFifo);
-    int i = 0;
-    while (size--) {
-        afsk_putchar(buffer[i++], NULL);
-    }
-}
-
 uint8_t AFSK_dac_isr(Afsk *afsk) {
     if (afsk->sampleIndex == 0) {
         if (afsk->txBit == 0) {

hardware/AFSK.h

@@ -39,7 +39,7 @@ inline static uint8_t sinSample(uint16_t i) {
 #define CPU_FREQ F_CPU
 
 
-#define BITRATE 2400
+#define BITRATE 1200
 
 #if BITRATE == 300
     #define CONFIG_ADC_SAMPLERATE 9600UL
@@ -49,16 +49,26 @@ inline static uint8_t sinSample(uint16_t i) {
     #define CONFIG_DAC_SAMPLERATE 19200UL
 #elif BITRATE == 2400
     #define CONFIG_ADC_SAMPLERATE 19200UL
-    #define CONFIG_DAC_SAMPLERATE 38400UL
+    #define CONFIG_DAC_SAMPLERATE 19200UL
 #endif
 
+#define CLOCK_TICKS_PER_SEC CONFIG_ADC_SAMPLERATE
 
 #define CONFIG_AFSK_RX_BUFLEN AX25_MAX_FRAME_LEN
 #define CONFIG_AFSK_TX_BUFLEN AX25_MAX_FRAME_LEN
 #define CONFIG_AFSK_RXTIMEOUT 0
 
-#define CONFIG_AFSK_PREAMBLE_LEN 150UL
-#define CONFIG_AFSK_TRAILER_LEN 25UL
+#if BITRATE == 300
+    #define CONFIG_AFSK_PREAMBLE_LEN 150UL
+    #define CONFIG_AFSK_TRAILER_LEN 10UL
+#elif BITRATE == 1200
+    #define CONFIG_AFSK_PREAMBLE_LEN 150UL
+    #define CONFIG_AFSK_TRAILER_LEN 10UL
+#elif BITRATE == 2400
+    #define CONFIG_AFSK_PREAMBLE_LEN 200UL
+    #define CONFIG_AFSK_TRAILER_LEN 25UL
+#endif
+
 #define BIT_STUFF_LEN 5
 
 #define ADC_SAMPLESPERBIT (CONFIG_ADC_SAMPLERATE / BITRATE)
@@ -230,7 +240,6 @@ typedef struct Afsk
 void AFSK_init(Afsk *afsk);
 void AFSK_adc_init(void);
 void AFSK_dac_init(void);
-void AFSK_transmit(char *buffer, size_t size);
 void AFSK_poll(Afsk *afsk);
 
 #endif

protocol/AX25.c

@@ -65,8 +65,7 @@ void ax25_poll(AX25Ctx *ctx) {
 
 }
 
-static void ax25_putchar(AX25Ctx *ctx, uint8_t c)
-{
+static void ax25_putchar(AX25Ctx *ctx, uint8_t c) {
     if (c == HDLC_FLAG || c == HDLC_RESET || c == AX25_ESC) fputc(AX25_ESC, ctx->ch);
     ctx->crc_out = update_crc_ccit(c, ctx->crc_out);
     fputc(c, ctx->ch);
@@ -89,5 +88,12 @@ void ax25_sendRaw(AX25Ctx *ctx, void *_buf, size_t len) {
 
     fputc(HDLC_FLAG, ctx->ch);
     
+    #if BITRATE == 2400
+        // Insert an extra sync section between long packet segments
+        for (uint8_t i = 0; i < 8; i++) {
+            fputc(HDLC_FLAG, ctx->ch);
+        }
+    #endif
+
     ctx->ready_for_data = true;
 }

protocol/KISS.c

@@ -4,6 +4,7 @@
 #include "device.h"
 #include "hardware/Serial.h"
 #include "util/FIFO16.h"
+#include "util/time.h"
 #include "KISS.h"
 
 uint8_t packet_queue[CONFIG_QUEUE_SIZE];
@@ -22,6 +23,7 @@ size_t packet_lengths_buf[CONFIG_QUEUE_MAX_LENGTH+1];
 AX25Ctx *ax25ctx;
 Afsk *channel;
 Serial *serial;
+volatile ticks_t last_serial_read = 0;
 size_t frame_len;
 bool IN_FRAME;
 bool ESCAPE;
@@ -50,6 +52,7 @@ void kiss_poll(void) {
     while (!fifo_isempty_locked(&serialFIFO)) {
         char sbyte = fifo_pop_locked(&serialFIFO);
         kiss_serialCallback(sbyte);
+        last_serial_read = timer_clock();
     }
 }
 
@@ -79,13 +82,26 @@ void kiss_messageCallback(AX25Ctx *ctx) {
 
 void kiss_csma(void) {
     if (queue_height > 0) {
-        if (!channel->hdlc.dcd) {
-            if (p == 255) {
-                kiss_flushQueue();
-            } else {
-                // TODO: Implement real CSMA
+        #if BITRATE == 2400
+            if (!channel->hdlc.dcd) {
+                ticks_t timeout = last_serial_read + ms_to_ticks(CONFIG_SERIAL_TIMEOUT_MS);
+                if (timer_clock() > timeout) {
+                    if (p == 255) {
+                        kiss_flushQueue();
+                    } else {
+                        // TODO: Implement real CSMA
+                    }
+                }
             }
-        }
+        #else
+            if (!channel->hdlc.dcd) {
+                if (p == 255) {
+                    kiss_flushQueue();
+                } else {
+                    // TODO: Implement real CSMA
+                }
+            }
+        #endif
     }
 }
 
@@ -117,7 +133,7 @@ void kiss_flushQueue(void) {
             size_t start = fifo16_pop_locked(&packet_starts);
             size_t length = fifo16_pop_locked(&packet_lengths);
 
-            kiss_poll();
+            //kiss_poll();
             for (size_t i = 0; i < length; i++) {
                 size_t pos = (start+i)%CONFIG_QUEUE_SIZE;
                 tx_buffer[i] = packet_queue[pos];
@@ -133,7 +149,7 @@ void kiss_flushQueue(void) {
                 LED_RX_ON();
             }
         }
-        printf("Processed %d\r\n", processed);
+        //printf("Processed %d\r\n", processed);
 
         queue_height = 0;
         queued_bytes = 0;
@@ -163,7 +179,7 @@ void kiss_serialCallback(uint8_t sbyte) {
             fifo16_push_locked(&packet_lengths, l);
 
             current_packet_start = queue_cursor;
-            printf("Queue height %d\r\n", queue_height);
+            //printf("Queue height %d\r\n", queue_height);
         }
         
     } else if (sbyte == FEND) {

util/time.h

@@ -2,9 +2,9 @@
 #define UTIL_TIME_H
 
 #include <util/atomic.h>
+#include "hardware/AFSK.h"
 
 #define DIV_ROUND(dividend, divisor)  (((dividend) + (divisor) / 2) / (divisor))
-#define CLOCK_TICKS_PER_SEC CONFIG_ADC_SAMPLERATE
 
 typedef int32_t ticks_t;
 typedef int32_t mtime_t;