altos-avr: Include serial/flight in companion commands

[fw/altos] / src-avr / ao_spi_slave.c

diff --git a/src-avr/ao_spi_slave.c b/src-avr/ao_spi_slave.c
index d44e4d0e0bafa81b0029b1475ed3185eaa77da3c..9ef30ead7d19cab604b35ee8ff1e02e02ac5fcf0 100644 (file)
--- a/src-avr/ao_spi_slave.c
+++ b/src-avr/ao_spi_slave.c
@@ -18,7 +18,8 @@
 #include "ao.h"
 #include "ao_product.h"
 
-static struct ao_companion_command     ao_companion_command;
+struct ao_companion_command    ao_companion_command;
+
 static const struct ao_companion_setup ao_companion_setup = {
        .board_id               = AO_idProduct_NUMBER,
        .board_id_inverse       = ~AO_idProduct_NUMBER,
@@ -26,29 +27,46 @@ static const struct ao_companion_setup      ao_companion_setup = {
        .channels               = NUM_ADC
 };
 
-static uint8_t ao_spi_slave_recv(void)
+static uint8_t
+ao_spi_read(uint8_t *buf, uint8_t len)
 {
-       uint8_t *buf;
-       uint8_t len;
-
-       len = sizeof (ao_companion_command);
-       buf = (uint8_t *) &ao_companion_command;
        while (len--) {
                while (!(SPSR & (1 << SPIF)))
                        if ((PINB & (1 << PINB0)))
                                return 0;
                *buf++ = SPDR;
        }
+       return 1;
+}
+
+static void
+ao_spi_write(uint8_t *buf, uint8_t len)
+{
+       while (len--) {
+               SPDR = *buf++;
+               while (!(SPSR & (1 << SPIF)))
+                       if ((PINB & (1 << PINB0)))
+                               return;
+       }
+       /* Clear pending SPIF bit by reading */
+       (void) SPDR;
+}
+
+static uint8_t ao_spi_slave_recv(void)
+{
+       if (!ao_spi_read((uint8_t *) &ao_companion_command,
+                        sizeof (ao_companion_command)))
+               return 0;
 
        /* Figure out the outbound data */
        switch (ao_companion_command.command) {
        case AO_COMPANION_SETUP:
-               buf = (uint8_t *) &ao_companion_setup;
-               len = sizeof (ao_companion_setup);
+               ao_spi_write((uint8_t *) &ao_companion_setup,
+                            sizeof (ao_companion_setup));
                break;
        case AO_COMPANION_FETCH:
-               buf = (uint8_t *) &ao_adc_ring[ao_adc_ring_prev(ao_adc_head)].adc;
-               len = NUM_ADC * sizeof (uint16_t);
+               ao_spi_write((uint8_t *) &ao_adc_ring[ao_adc_ring_prev(ao_adc_head)].adc,
+                            NUM_ADC * sizeof (uint16_t));
                break;
        case AO_COMPANION_STATE:
                break;
@@ -56,16 +74,6 @@ static uint8_t ao_spi_slave_recv(void)
                return 0;
        }
 
-       if (len) {
-               /* Send the outbound data */
-               while (len--) {
-                       SPDR = *buf++;
-                       while (!(SPSR & (1 << SPIF)))
-                               if ((PINB & (1 << PINB0)))
-                                       return 0;
-               }
-               (void) SPDR;
-       }
        ao_log_store.tm_tick = ao_companion_command.tick;
        if (ao_log_store.tm_state != ao_companion_command.flight_state) {
                ao_log_store.tm_state = ao_companion_command.flight_state;
@@ -107,7 +115,24 @@ ao_spi_slave_init(void)
        PCMSK0 |= (1 << PCINT0);        /* Enable PCINT0 pin change */
        PCICR |= (1 << PCIE0);          /* Enable pin change interrupt */
 
-       DDRB = (DDRB & 0xf0) | (1 << 3);
+       DDRB = ((DDRB & 0xf0) |
+               (1 << 3) |              /* MISO, output */
+               (0 << 2) |              /* MOSI, input */
+               (0 << 1) |              /* SCK, input */
+               (0 << 0));              /* SS, input */
+
+       /* We'd like to have a pull-up on SS so that disconnecting the
+        * TM would cause any SPI transaction to abort. However, when
+        * I tried that, SPI transactions would spontaneously abort,
+        * making me assume that we needed a less aggressive pull-up
+        * than is offered inside the AVR
+        */
+       PORTB = ((PORTB & 0xf0) |
+                (1 << 3) |             /* MISO, output */
+                (0 << 2) |             /* MOSI, no pull-up */
+                (0 << 1) |             /* SCK, no pull-up */
+                (0 << 0));             /* SS, no pull-up */
+
        SPCR = (0 << SPIE) |            /* Disable SPI interrupts */
                (1 << SPE) |            /* Enable SPI */
                (0 << DORD) |           /* MSB first */