altos: Fix up APRS packet sending code in cc1120 driver

This fixes the FIFO management, ensuring that the data are streamed
into the radio fast enough to keep the packet continuous. Sounds like
it works, but testing with an actual APRS receiver is required.

Signed-off-by: Keith Packard <keithp@keithp.com>

diff --git a/src/drivers/ao_cc1120.c b/src/drivers/ao_cc1120.c
index ed26e28d3fbea55b4a25c91767b8ab09793bc8a7..7654af856a624b0b55c76b238ad55354317239e1 100644 (file)
--- a/src/drivers/ao_cc1120.c
+++ b/src/drivers/ao_cc1120.c
@@ -261,7 +261,7 @@ ao_radio_idle(void)
 #define PACKET_DEV_M   80
 
 /*
- * For our packet data, set the symbol rate to 38360 Baud
+ * For our packet data, set the symbol rate to 38400 Baud
  *
  *              (2**20 + DATARATE_M) * 2 ** DATARATE_E
  *     Rdata = -------------------------------------- * fosc
@@ -383,8 +383,8 @@ static const uint16_t rdf_setup[] = {
  *     Rdata = 9599.998593330383301
  *
  */
-#define APRS_DRATE_E   5
-#define APRS_DRATE_M   25166
+#define APRS_DRATE_E   7
+#define APRS_DRATE_M   239914
 
 static const uint16_t aprs_setup[] = {
        CC1120_DEVIATION_M,     APRS_DEV_M,
@@ -432,8 +432,9 @@ static uint16_t ao_radio_mode;
 #define AO_RADIO_MODE_PACKET_TX_FINISH (AO_RADIO_MODE_BITS_PACKET | AO_RADIO_MODE_BITS_PACKET_TX | AO_RADIO_MODE_BITS_TX_FINISH)
 #define AO_RADIO_MODE_PACKET_RX                (AO_RADIO_MODE_BITS_PACKET | AO_RADIO_MODE_BITS_PACKET_RX)
 #define AO_RADIO_MODE_RDF              (AO_RADIO_MODE_BITS_RDF | AO_RADIO_MODE_BITS_TX_FINISH)
-#define AO_RADIO_MODE_APRS_BUF         (AO_RADIO_MODE_BITS_APRS | AO_RADIO_MODE_BITS_INFINITE)
-#define AO_RADIO_MODE_APRS_FINISH      (AO_RADIO_MODE_BITS_APRS | AO_RADIO_MODE_BITS_FIXED)
+#define AO_RADIO_MODE_APRS_BUF         (AO_RADIO_MODE_BITS_APRS | AO_RADIO_MODE_BITS_INFINITE | AO_RADIO_MODE_BITS_TX_BUF)
+#define AO_RADIO_MODE_APRS_LAST_BUF    (AO_RADIO_MODE_BITS_APRS | AO_RADIO_MODE_BITS_FIXED | AO_RADIO_MODE_BITS_TX_BUF)
+#define AO_RADIO_MODE_APRS_FINISH      (AO_RADIO_MODE_BITS_APRS | AO_RADIO_MODE_BITS_FIXED | AO_RADIO_MODE_BITS_TX_FINISH)
 
 static void
 ao_radio_set_mode(uint16_t new_mode)
@@ -642,17 +643,23 @@ ao_radio_test_cmd(void)
        }
 }
 
+static void
+ao_radio_wait_isr(void)
+{
+       ao_radio_wake = 0;
+       ao_arch_block_interrupts();
+       while (!ao_radio_wake)
+               ao_sleep(&ao_radio_wake);
+       ao_arch_release_interrupts();
+}
+
 static uint8_t
 ao_radio_wait_tx(uint8_t wait_fifo)
 {
        uint8_t fifo_space = 0;
 
        do {
-               ao_radio_wake = 0;
-               ao_arch_block_interrupts();
-               while (!ao_radio_wake)
-                       ao_sleep(&ao_radio_wake);
-               ao_arch_release_interrupts();
+               ao_radio_wait_isr();
                if (!wait_fifo)
                        return 0;
                fifo_space = ao_radio_tx_fifo_space();
@@ -725,25 +732,47 @@ ao_radio_send_lots(ao_radio_fill_func fill)
                        cnt = -cnt;
                }
                total += cnt;
-               if (done) {
+
+               /* At the last buffer, set the total length */
+               if (done)
                        ao_radio_set_len(total & 0xff);
-                       ao_radio_set_mode(AO_RADIO_MODE_APRS_FINISH);
-               } else
-                       ao_radio_set_mode(AO_RADIO_MODE_APRS_BUF);
+
                b = buf;
                while (cnt) {
                        uint8_t this_len = cnt;
+
+                       /* Wait for some space in the fifo */
+                       while ((fifo_space = ao_radio_tx_fifo_space()) == 0) {
+                               ao_radio_wake = 0;
+                               ao_arch_block_interrupts();
+                               while (!ao_radio_wake)
+                                       ao_sleep(&ao_radio_wake);
+                               ao_arch_release_interrupts();
+                       }
                        if (this_len > fifo_space)
                                this_len = fifo_space;
+
+                       cnt -= this_len;
+
+                       if (done) {
+                               if (cnt)
+                                       ao_radio_set_mode(AO_RADIO_MODE_APRS_LAST_BUF);
+                               else
+                                       ao_radio_set_mode(AO_RADIO_MODE_APRS_FINISH);
+                       } else
+                               ao_radio_set_mode(AO_RADIO_MODE_APRS_BUF);
+
                        ao_radio_fifo_write(b, this_len);
                        b += this_len;
-                       cnt -= this_len;
+
                        if (!started) {
                                ao_radio_start_tx();
                                started = 1;
-                       }
-                       fifo_space = ao_radio_wait_tx(!done || cnt);
+                       } else
+                               ao_exti_enable(AO_CC1120_INT_PORT, AO_CC1120_INT_PIN);
                }
+               /* Wait for the transmitter to go idle */
+               ao_radio_wait_isr();
        }
        ao_radio_put();
 }
@@ -1140,11 +1169,21 @@ ao_radio_test_recv()
        }
 }
 
+#include <ao_aprs.h>
+
+static void
+ao_radio_aprs()
+{
+       ao_packet_slave_stop();
+       ao_aprs_send();
+}
+
 #endif
 
 static const struct ao_cmds ao_radio_cmds[] = {
        { ao_radio_test_cmd,    "C <1 start, 0 stop, none both>\0Radio carrier test" },
 #if CC1120_DEBUG
+       { ao_radio_aprs,        "G\0Send APRS packet" },
        { ao_radio_show,        "R\0Show CC1120 status" },
        { ao_radio_beep,        "b\0Emit an RDF beacon" },
        { ao_radio_packet,      "p\0Send a test packet" },