/**
******************************************************************************
* @addtogroup PIOS PIOS Core hardware abstraction layer
* @{
* @addtogroup PIOS_SRXL Multiplex SRXL receiver functions
* @brief Code to read Multiplex SRXL receiver serial stream
* @{
*
* @file pios_srxl.c
* @author The OpenPilot Team, http://www.openpilot.org Copyright (C) 2015.
* @brief Code to read Multiplex SRXL receiver serial stream
* @see The GNU Public License (GPL) Version 3
*
*****************************************************************************/
/*
* 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; either version 3 of the License, or
* (at your option) any later version.
*
* 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 "pios.h"
#ifdef PIOS_INCLUDE_SRXL
#include "pios_srxl_priv.h"
// #define PIOS_INSTRUMENT_MODULE
#include <pios_instrumentation_helper.h>
PERF_DEFINE_COUNTER(crcFailureCount);
PERF_DEFINE_COUNTER(failsafeCount);
PERF_DEFINE_COUNTER(successfulCount);
PERF_DEFINE_COUNTER(messageUnrollTimer);
PERF_DEFINE_COUNTER(messageReceiveRate);
PERF_DEFINE_COUNTER(receivedBytesCount);
PERF_DEFINE_COUNTER(frameStartCount);
PERF_DEFINE_COUNTER(frameAbortCount);
PERF_DEFINE_COUNTER(completeMessageCount);
/* Forward Declarations */
static int32_t PIOS_SRXL_Get(uint32_t rcvr_id, uint8_t channel);
static uint16_t PIOS_SRXL_RxInCallback(uint32_t context,
uint8_t *buf,
uint16_t buf_len,
uint16_t *headroom,
bool *need_yield);
static void PIOS_SRXL_Supervisor(uint32_t srxl_id);
/* Local Variables */
const struct pios_rcvr_driver pios_srxl_rcvr_driver = {
.read = PIOS_SRXL_Get,
};
enum pios_srxl_dev_magic {
PIOS_SRXL_DEV_MAGIC = 0x55545970,
};
struct pios_srxl_state {
uint16_t channel_data[PIOS_SRXL_NUM_INPUTS];
uint8_t received_data[SRXL_FRAME_LENGTH];
uint8_t receive_timer;
uint8_t failsafe_timer;
uint8_t frame_found;
uint8_t byte_count;
uint8_t data_bytes;
};
struct pios_srxl_dev {
enum pios_srxl_dev_magic magic;
struct pios_srxl_state state;
};
/* Allocate S.Bus device descriptor */
#if defined(PIOS_INCLUDE_FREERTOS)
static struct pios_srxl_dev *PIOS_SRXL_Alloc(void)
{
struct pios_srxl_dev *srxl_dev;
srxl_dev = (struct pios_srxl_dev *)pios_malloc(sizeof(*srxl_dev));
if (!srxl_dev) {
return NULL;
}
srxl_dev->magic = PIOS_SRXL_DEV_MAGIC;
return srxl_dev;
}
#else
static struct pios_srxl_dev pios_srxl_devs[PIOS_SRXL_MAX_DEVS];
static uint8_t pios_srxl_num_devs;
static struct pios_srxl_dev *PIOS_SRXL_Alloc(void)
{
struct pios_srxl_dev *srxl_dev;
if (pios_srxl_num_devs >= PIOS_SRXL_MAX_DEVS) {
return NULL;
}
srxl_dev = &pios_srxl_devs[pios_srxl_num_devs++];
srxl_dev->magic = PIOS_SRXL_DEV_MAGIC;
return srxl_dev;
}
#endif /* if defined(PIOS_INCLUDE_FREERTOS) */
/* Validate SRXL device descriptor */
static bool PIOS_SRXL_Validate(struct pios_srxl_dev *srxl_dev)
{
return srxl_dev->magic == PIOS_SRXL_DEV_MAGIC;
}
/* Reset channels in case of lost signal or explicit failsafe receiver flag */
static void PIOS_SRXL_ResetChannels(struct pios_srxl_state *state)
{
for (int i = 0; i < PIOS_SRXL_NUM_INPUTS; i++) {
state->channel_data[i] = PIOS_RCVR_TIMEOUT;
}
}
/* Reset SRXL receiver state */
static void PIOS_SRXL_ResetState(struct pios_srxl_state *state)
{
state->receive_timer = 0;
state->failsafe_timer = 0;
state->frame_found = 0;
state->data_bytes = 0;
PIOS_SRXL_ResetChannels(state);
}
/* Initialize SRXL receiver interface */
int32_t PIOS_SRXL_Init(uint32_t *srxl_id,
const struct pios_com_driver *driver,
uint32_t lower_id)
{
PIOS_DEBUG_Assert(srxl_id);
PIOS_DEBUG_Assert(driver);
struct pios_srxl_dev *srxl_dev;
srxl_dev = (struct pios_srxl_dev *)PIOS_SRXL_Alloc();
if (!srxl_dev) {
goto out_fail;
}
PIOS_SRXL_ResetState(&(srxl_dev->state));
*srxl_id = (uint32_t)srxl_dev;
/* Set comm driver callback */
(driver->bind_rx_cb)(lower_id, PIOS_SRXL_RxInCallback, *srxl_id);
if (!PIOS_RTC_RegisterTickCallback(PIOS_SRXL_Supervisor, *srxl_id)) {
PIOS_DEBUG_Assert(0);
}
PERF_INIT_COUNTER(crcFailureCount, 0x5551);
PERF_INIT_COUNTER(failsafeCount, 0x5552);
PERF_INIT_COUNTER(successfulCount, 0x5553);
PERF_INIT_COUNTER(messageUnrollTimer, 0x5554);
PERF_INIT_COUNTER(messageReceiveRate, 0x5555);
PERF_INIT_COUNTER(receivedBytesCount, 0x5556);
PERF_INIT_COUNTER(frameStartCount, 0x5557);
PERF_INIT_COUNTER(frameAbortCount, 0x5558);
PERF_INIT_COUNTER(completeMessageCount, 0x5559);
return 0;
out_fail:
return -1;
}
/**
* Get the value of an input channel
* \param[in] channel Number of the channel desired (zero based)
* \output PIOS_RCVR_INVALID channel not available
* \output PIOS_RCVR_TIMEOUT failsafe condition or missing receiver
* \output >=0 channel value
*/
static int32_t PIOS_SRXL_Get(uint32_t rcvr_id, uint8_t channel)
{
struct pios_srxl_dev *srxl_dev = (struct pios_srxl_dev *)rcvr_id;
if (!PIOS_SRXL_Validate(srxl_dev)) {
return PIOS_RCVR_INVALID;
}
/* return error if channel is not available */
if (channel >= PIOS_SRXL_NUM_INPUTS) {
return PIOS_RCVR_INVALID;
}
return srxl_dev->state.channel_data[channel];
}
static void PIOS_SRXL_UnrollChannels(struct pios_srxl_state *state)
{
PERF_TIMED_SECTION_START(messageUnrollTimer);
uint8_t *received_data = state->received_data;
uint8_t channel;
uint16_t channel_value;
for (channel = 0; channel < (state->data_bytes / 2); channel++) {
channel_value = ((uint16_t)received_data[SRXL_HEADER_LENGTH + (channel * 2)]) << 8;
channel_value = channel_value + ((uint16_t)received_data[SRXL_HEADER_LENGTH + (channel * 2) + 1]);
state->channel_data[channel] = (800 + ((channel_value * 1400) >> 12));
}
PERF_TIMED_SECTION_END(messageUnrollTimer);
}
static bool PIOS_SRXL_Validate_Checksum(struct pios_srxl_state *state)
{
// Check the CRC16 checksum. The provided checksum is immediately after the channel data.
// All data including start byte and version byte is included in crc calculation.
uint8_t i = 0;
uint16_t crc = 0;
for (i = 0; i < SRXL_HEADER_LENGTH + state->data_bytes; i++) {
crc = crc ^ (int16_t)state->received_data[i] << 8;
uint8_t j = 0;
for (j = 0; j < 8; j++) {
if (crc & 0x8000) {
crc = crc << 1 ^ 0x1021;
} else {
crc = crc << 1;
}
}
}
uint16_t checksum = (((uint16_t)(state->received_data[i] << 8) |
(uint16_t)state->received_data[i + 1]));
return crc == checksum;
}
/* Update decoder state processing input byte from the SRXL stream */
static void PIOS_SRXL_UpdateState(struct pios_srxl_state *state, uint8_t b)
{
/* should not process any data until new frame is found */
if (!state->frame_found) {
return;
}
if (state->byte_count < (SRXL_HEADER_LENGTH + state->data_bytes + SRXL_CHECKSUM_LENGTH)) {
if (state->byte_count == 0) {
// Set up the length of the channel data according to version received
PERF_INCREMENT_VALUE(frameStartCount);
if (b == SRXL_V1_HEADER) {
state->data_bytes = SRXL_V1_CHANNEL_DATA_BYTES;
} else if (b == SRXL_V2_HEADER) {
state->data_bytes = SRXL_V2_CHANNEL_DATA_BYTES;
} else {
/* discard the whole frame if the 1st byte is not correct */
state->frame_found = 0;
PERF_INCREMENT_VALUE(frameAbortCount);
return;
}
}
/* store next byte */
state->received_data[state->byte_count] = b;
state->byte_count++;
if (state->byte_count == (SRXL_HEADER_LENGTH + state->data_bytes + SRXL_CHECKSUM_LENGTH)) {
PERF_INCREMENT_VALUE(completeMessageCount);
// We have a complete message, lets decode it
if (PIOS_SRXL_Validate_Checksum(state)) {
/* data looking good */
PIOS_SRXL_UnrollChannels(state);
state->failsafe_timer = 0;
PERF_INCREMENT_VALUE(successfulCount);
} else {
/* discard whole frame */
PERF_INCREMENT_VALUE(crcFailureCount);
}
/* prepare for the next frame */
state->frame_found = 0;
PERF_MEASURE_PERIOD(messageReceiveRate);
}
}
}
/* Comm byte received callback */
static uint16_t PIOS_SRXL_RxInCallback(uint32_t context,
uint8_t *buf,
uint16_t buf_len,
uint16_t *headroom,
bool *need_yield)
{
struct pios_srxl_dev *srxl_dev = (struct pios_srxl_dev *)context;
bool valid = PIOS_SRXL_Validate(srxl_dev);
PIOS_Assert(valid);
struct pios_srxl_state *state = &(srxl_dev->state);
/* process byte(s) and clear receive timer */
for (uint8_t i = 0; i < buf_len; i++) {
PIOS_SRXL_UpdateState(state, buf[i]);
state->receive_timer = 0;
PERF_INCREMENT_VALUE(receivedBytesCount);
}
/* Always signal that we can accept another byte */
if (headroom) {
*headroom = SRXL_FRAME_LENGTH;
}
/* We never need a yield */
*need_yield = false;
/* Always indicate that all bytes were consumed */
return buf_len;
}
/**
* Input data supervisor is called periodically and provides
* two functions: frame syncing and failsafe triggering.
*
* Multiplex SRXL frames come at 14ms (FastResponse ON) or 21ms (FastResponse OFF)
* rate at 115200bps.
* RTC timer is running at 625Hz (1.6ms). So with divider 2 it gives
* 3.2ms pause between frames which is good for both SRXL frame rates.
*
* Data receive function must clear the receive_timer to confirm new
* data reception. If no new data received in 100ms, we must call the
* failsafe function which clears all channels.
*/
static void PIOS_SRXL_Supervisor(uint32_t srxl_id)
{
struct pios_srxl_dev *srxl_dev = (struct pios_srxl_dev *)srxl_id;
bool valid = PIOS_SRXL_Validate(srxl_dev);
PIOS_Assert(valid);
struct pios_srxl_state *state = &(srxl_dev->state);
/* waiting for new frame if no bytes were received in 6.4ms */
if (++state->receive_timer > 4) {
state->frame_found = 1;
state->byte_count = 0;
state->receive_timer = 0;
}
/* activate failsafe if no frames have arrived in 102.4ms */
if (++state->failsafe_timer > 64) {
PIOS_SRXL_ResetChannels(state);
state->failsafe_timer = 0;
PERF_INCREMENT_VALUE(failsafeCount);
}
}
#endif /* PIOS_INCLUDE_SRXL */
/**
* @}
* @}
*/