ardupilot/libraries/AP_HAL_AVR/SPIDevice_SPI0.cpp

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#include <AP_HAL/AP_HAL.h>
#if (CONFIG_HAL_BOARD == HAL_BOARD_APM1 || CONFIG_HAL_BOARD == HAL_BOARD_APM2)
#include <avr/io.h>
#include <AP_HAL/AP_HAL.h>
#include "SPIDevices.h"
#include "GPIO.h"
#include "Semaphores.h"
#include "utility/pins_arduino_mega.h"
using namespace AP_HAL_AVR;
extern const AP_HAL::HAL& hal;
#define SPI0_MISO_PIN 50
#define SPI0_MOSI_PIN 51
#define SPI0_SCK_PIN 52
AVRSemaphore AVRSPI0DeviceDriver::_semaphore;
bool AVRSPI0DeviceDriver::_force_low_speed;
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static volatile bool spi0_transferflag = false;
void AVRSPI0DeviceDriver::init() {
hal.gpio->pinMode(SPI0_MISO_PIN, HAL_GPIO_INPUT);
hal.gpio->pinMode(SPI0_MOSI_PIN, HAL_GPIO_OUTPUT);
hal.gpio->pinMode(SPI0_SCK_PIN, HAL_GPIO_OUTPUT);
_cs_pin->mode(HAL_GPIO_OUTPUT);
_cs_pin->write(1);
/* Enable the SPI0 peripheral as a master */
SPCR = _BV(SPE) | _BV(MSTR);
}
AP_HAL::Semaphore* AVRSPI0DeviceDriver::get_semaphore() {
return &_semaphore;
}
void AVRSPI0DeviceDriver::_cs_assert()
{
const uint8_t valid_spcr_mask =
(_BV(CPOL) | _BV(CPHA) | _BV(SPR1) | _BV(SPR0));
if (_force_low_speed) {
_spcr = _spcr_lowspeed;
}
uint8_t new_spcr = (SPCR & ~valid_spcr_mask) | (_spcr & valid_spcr_mask);
SPCR = new_spcr;
const uint8_t valid_spsr_mask = _BV(SPI2X);
uint8_t new_spsr = (SPSR & ~valid_spsr_mask) | (_spsr & valid_spsr_mask);
SPSR = new_spsr;
_cs_pin->write(0);
}
void AVRSPI0DeviceDriver::_cs_release()
{
_cs_pin->write(1);
}
uint8_t AVRSPI0DeviceDriver::_transfer(uint8_t data)
{
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if (spi0_transferflag) {
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hal.scheduler->panic(PSTR("PANIC: SPI0 transfer collision"));
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}
spi0_transferflag = true;
SPDR = data;
if (SPSR & _BV(WCOL)) {
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hal.scheduler->panic(PSTR("PANIC: SPI0 write collision"));
return 0;
}
while(!(SPSR & _BV(SPIF)));
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uint8_t read_spdr = SPDR;
spi0_transferflag = false;
return read_spdr;
}
/**
a specialised transfer function for the MPU6k. This saves 2 usec
per byte
*/
void AVRSPI0DeviceDriver::_transfer16(const uint8_t *tx, uint8_t *rx)
{
spi0_transferflag = true;
#define TRANSFER1(i) do { SPDR = tx[i]; while(!(SPSR & _BV(SPIF))); rx[i] = SPDR; } while(0)
TRANSFER1(0);
TRANSFER1(1);
TRANSFER1(2);
TRANSFER1(3);
TRANSFER1(4);
TRANSFER1(5);
TRANSFER1(6);
TRANSFER1(7);
TRANSFER1(8);
TRANSFER1(9);
TRANSFER1(10);
TRANSFER1(11);
TRANSFER1(12);
TRANSFER1(13);
TRANSFER1(14);
TRANSFER1(15);
spi0_transferflag = false;
}
void AVRSPI0DeviceDriver::transfer(const uint8_t *tx, uint16_t len) {
for (uint16_t i = 0; i < len; i++) {
_transfer(tx[i]);
}
}
bool AVRSPI0DeviceDriver::transaction(const uint8_t *tx, uint8_t *rx,
uint16_t len) {
_cs_assert();
if (rx == NULL) {
for (uint16_t i = 0; i < len; i++) {
_transfer(tx[i]);
}
} else {
while (len >= 16) {
_transfer16(tx, rx);
tx += 16;
rx += 16;
len -= 16;
}
for (uint16_t i = 0; i < len; i++) {
rx[i] = _transfer(tx[i]);
}
}
_cs_release();
return true;
}
void AVRSPI0DeviceDriver::cs_assert() {
_cs_assert();
}
void AVRSPI0DeviceDriver::cs_release() {
_cs_release();
}
uint8_t AVRSPI0DeviceDriver::transfer(uint8_t data) {
return _transfer(data);
}
/**
allow on the fly bus speed changes for MPU6000
*/
void AVRSPI0DeviceDriver::set_bus_speed(AVRSPI0DeviceDriver::bus_speed speed)
{
if (speed == AVRSPI0DeviceDriver::SPI_SPEED_HIGH) {
_spcr = _spcr_highspeed;
_force_low_speed = false;
} else {
_spcr = _spcr_lowspeed;
_force_low_speed = true;
}
}
#endif