diff options
Diffstat (limited to 'src/avr/ao_spi_slave.c')
| -rw-r--r-- | src/avr/ao_spi_slave.c | 142 |
1 files changed, 142 insertions, 0 deletions
diff --git a/src/avr/ao_spi_slave.c b/src/avr/ao_spi_slave.c new file mode 100644 index 00000000..4dde09f3 --- /dev/null +++ b/src/avr/ao_spi_slave.c @@ -0,0 +1,142 @@ +/* + * Copyright © 2011 Keith Packard <keithp@keithp.com> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; version 2 of the License. + * + * This program is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + * + * You should have received a copy of the GNU General Public License along + * with this program; if not, write to the Free Software Foundation, Inc., + * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA. + */ + +#include "ao.h" +#include "ao_product.h" + +struct ao_companion_command ao_companion_command; + +static const struct ao_companion_setup ao_telescience_setup = { + .board_id = AO_idProduct_NUMBER, + .board_id_inverse = ~AO_idProduct_NUMBER, + .update_period = 50, + .channels = AO_LOG_TELESCIENCE_NUM_ADC, +}; + +static uint8_t +ao_spi_read(uint8_t *buf, uint8_t len) +{ + 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: + ao_spi_write((uint8_t *) &ao_telescience_setup, + sizeof (ao_telescience_setup)); + break; + case AO_COMPANION_FETCH: + ao_spi_write((uint8_t *) &ao_adc_ring[ao_adc_ring_prev(ao_adc_head)].adc, + AO_LOG_TELESCIENCE_NUM_ADC * sizeof (uint16_t)); + break; + case AO_COMPANION_NOTIFY: + break; + default: + return 0; + } + + 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; + return 1; + } + return 0; +} + +static uint8_t ao_spi_slave_running; + +ISR(PCINT0_vect) +{ + if ((PINB & (1 << PINB0)) == 0) { + if (!ao_spi_slave_running) { + uint8_t changed; + ao_spi_slave_running = 1; + cli(); + changed = ao_spi_slave_recv(); + sei(); + if (changed && ao_flight_boost <= ao_log_store.tm_state) { + if (ao_log_store.tm_state < ao_flight_landed) + ao_log_start(); + else + ao_log_stop(); + } + } + } else { + ao_spi_slave_running = 0; + } +} + +void ao_spi_slave_debug(void) { + printf ("slave running %d\n", ao_spi_slave_running); +} + +void +ao_spi_slave_init(void) +{ + PCMSK0 |= (1 << PCINT0); /* Enable PCINT0 pin change */ + PCICR |= (1 << PCIE0); /* Enable pin change interrupt */ + + 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 */ + (0 << MSTR) | /* Slave mode */ + (0 << CPOL) | /* Clock low when idle */ + (0 << CPHA); /* Sample at leading clock edge */ +} |