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   1 /*
   2  * Copyright © 2011 Keith Packard <keithp@keithp.com>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; version 2 of the License.
   7  *
   8  * This program is distributed in the hope that it will be useful, but
   9  * WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along
  14  * with this program; if not, write to the Free Software Foundation, Inc.,
  15  * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
  16  */
  17
  18 #include "ao.h"
  19 #include "ao_product.h"
  20
  21 struct ao_companion_command     ao_companion_command;
  22
  23 static const struct ao_companion_setup  ao_telescience_setup = {
  24         .board_id               = AO_idProduct_NUMBER,
  25         .board_id_inverse       = ~AO_idProduct_NUMBER,
  26         .update_period          = 50,
  27         .channels               = AO_LOG_TELESCIENCE_NUM_ADC,
  28 };
  29
  30 static uint8_t
  31 ao_spi_read(uint8_t *buf, uint8_t len)
  32 {
  33         while (len--) {
  34                 while (!(SPSR & (1 << SPIF)))
  35                         if ((PINB & (1 << PINB0)))
  36                                 return 0;
  37                 *buf++ = SPDR;
  38         }
  39         return 1;
  40 }
  41
  42 static void
  43 ao_spi_write(uint8_t *buf, uint8_t len)
  44 {
  45         while (len--) {
  46                 SPDR = *buf++;
  47                 while (!(SPSR & (1 << SPIF)))
  48                         if ((PINB & (1 << PINB0)))
  49                                 return;
  50         }
  51         /* Clear pending SPIF bit by reading */
  52         (void) SPDR;
  53 }
  54
  55 static uint8_t ao_spi_slave_recv(void)
  56 {
  57         if (!ao_spi_read((uint8_t *) &ao_companion_command,
  58                          sizeof (ao_companion_command)))
  59                 return 0;
  60
  61         /* Figure out the outbound data */
  62         switch (ao_companion_command.command) {
  63         case AO_COMPANION_SETUP:
  64                 ao_spi_write((uint8_t *) &ao_telescience_setup,
  65                              sizeof (ao_telescience_setup));
  66                 break;
  67         case AO_COMPANION_FETCH:
  68                 ao_spi_write((uint8_t *) &ao_adc_ring[ao_adc_ring_prev(ao_adc_head)].adc,
  69                              AO_LOG_TELESCIENCE_NUM_ADC * sizeof (uint16_t));
  70                 break;
  71         case AO_COMPANION_NOTIFY:
  72                 break;
  73         default:
  74                 return 0;
  75         }
  76
  77         ao_log_single_write_data.telescience.tm_tick = ao_companion_command.tick;
  78         if (ao_log_single_write_data.telescience.tm_state != ao_companion_command.flight_state) {
  79                 ao_log_single_write_data.telescience.tm_state = ao_companion_command.flight_state;
  80                 return 1;
  81         }
  82         return 0;
  83 }
  84
  85 static uint8_t ao_spi_slave_running;
  86
  87 ISR(PCINT0_vect)
  88 {
  89         if ((PINB & (1 << PINB0)) == 0) {
  90                 if (!ao_spi_slave_running) {
  91                         uint8_t changed;
  92                         ao_spi_slave_running = 1;
  93                         cli();
  94                         changed = ao_spi_slave_recv();
  95                         sei();
  96                         if (changed && ao_flight_boost <= ao_log_single_write_data.telescience.tm_state) {
  97                                 if (ao_log_single_write_data.telescience.tm_state < ao_flight_landed)
  98                                         ao_log_single_start();
  99                                 else
 100                                         ao_log_single_stop();
 101                         }
 102                 }
 103         } else {
 104                 ao_spi_slave_running = 0;
 105         }
 106 }
 107
 108 void ao_spi_slave_debug(void) {
 109         printf ("slave running %d\n", ao_spi_slave_running);
 110 }
 111
 112 void
 113 ao_spi_slave_init(void)
 114 {
 115         PCMSK0 |= (1 << PCINT0);        /* Enable PCINT0 pin change */
 116         PCICR |= (1 << PCIE0);          /* Enable pin change interrupt */
 117
 118         DDRB = ((DDRB & 0xf0) |
 119                 (1 << 3) |              /* MISO, output */
 120                 (0 << 2) |              /* MOSI, input */
 121                 (0 << 1) |              /* SCK, input */
 122                 (0 << 0));              /* SS, input */
 123
 124         /* We'd like to have a pull-up on SS so that disconnecting the
 125          * TM would cause any SPI transaction to abort. However, when
 126          * I tried that, SPI transactions would spontaneously abort,
 127          * making me assume that we needed a less aggressive pull-up
 128          * than is offered inside the AVR
 129          */
 130         PORTB = ((PORTB & 0xf0) |
 131                  (1 << 3) |             /* MISO, output */
 132                  (0 << 2) |             /* MOSI, no pull-up */
 133                  (0 << 1) |             /* SCK, no pull-up */
 134                  (0 << 0));             /* SS, no pull-up */
 135
 136         SPCR = (0 << SPIE) |            /* Disable SPI interrupts */
 137                 (1 << SPE) |            /* Enable SPI */
 138                 (0 << DORD) |           /* MSB first */
 139                 (0 << MSTR) |           /* Slave mode */
 140                 (0 << CPOL) |           /* Clock low when idle */
 141                 (0 << CPHA);            /* Sample at leading clock edge */
 142 }