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443 lines
13 KiB
C
443 lines
13 KiB
C
/**
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******************************************************************************
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* @addtogroup PIOS PIOS Core hardware abstraction layer
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* @{
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* @addtogroup PIOS_DSM Spektrum/JR DSMx satellite receiver functions
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* @brief Code to bind and read Spektrum/JR DSMx satellite receiver serial stream
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* @{
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*
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* @file pios_dsm.c
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* @author The OpenPilot Team, http://www.openpilot.org Copyright (C) 2012.
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* @brief Code bind and read Spektrum/JR DSMx satellite receiver serial stream
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* @see The GNU Public License (GPL) Version 3
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*
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*****************************************************************************/
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/*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#include "pios.h"
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#ifdef PIOS_INCLUDE_DSM
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#include "pios_dsm_priv.h"
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// *** UNTESTED CODE ***
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#undef DSM_LINK_QUALITY
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#ifndef PIOS_INCLUDE_RTC
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#error PIOS_INCLUDE_RTC must be used to use DSM
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#endif
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/* Forward Declarations */
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static int32_t PIOS_DSM_Get(uint32_t rcvr_id, uint8_t channel);
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static uint8_t PIOS_DSM_Quality_Get(uint32_t rcvr_id);
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static uint16_t PIOS_DSM_RxInCallback(uint32_t context,
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uint8_t *buf,
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uint16_t buf_len,
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uint16_t *headroom,
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bool *need_yield);
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static void PIOS_DSM_Supervisor(uint32_t dsm_id);
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/* Local Variables */
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const struct pios_rcvr_driver pios_dsm_rcvr_driver = {
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.read = PIOS_DSM_Get,
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.get_quality = PIOS_DSM_Quality_Get
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};
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enum pios_dsm_dev_magic {
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PIOS_DSM_DEV_MAGIC = 0x44534d78,
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};
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struct pios_dsm_state {
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uint16_t channel_data[PIOS_DSM_NUM_INPUTS];
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uint8_t received_data[DSM_FRAME_LENGTH];
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uint8_t receive_timer;
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uint8_t failsafe_timer;
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uint8_t frame_found;
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uint8_t byte_count;
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uint8_t frames_lost_last;
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float quality;
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};
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/* With an DSM frame rate of 11ms (90Hz) averaging over 18 samples
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* gives about a 200ms response.
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*/
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#define DSM_FL_WEIGHTED_AVE 18
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struct pios_dsm_dev {
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enum pios_dsm_dev_magic magic;
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const struct pios_dsm_cfg *cfg;
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struct pios_dsm_state state;
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};
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/* Allocate DSM device descriptor */
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#if defined(PIOS_INCLUDE_FREERTOS)
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static struct pios_dsm_dev *PIOS_DSM_Alloc(void)
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{
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struct pios_dsm_dev *dsm_dev;
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dsm_dev = (struct pios_dsm_dev *)pios_malloc(sizeof(*dsm_dev));
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if (!dsm_dev) {
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return NULL;
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}
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dsm_dev->magic = PIOS_DSM_DEV_MAGIC;
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return dsm_dev;
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}
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#else
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static struct pios_dsm_dev pios_dsm_devs[PIOS_DSM_MAX_DEVS];
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static uint8_t pios_dsm_num_devs;
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static struct pios_dsm_dev *PIOS_DSM_Alloc(void)
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{
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struct pios_dsm_dev *dsm_dev;
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if (pios_dsm_num_devs >= PIOS_DSM_MAX_DEVS) {
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return NULL;
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}
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dsm_dev = &pios_dsm_devs[pios_dsm_num_devs++];
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dsm_dev->magic = PIOS_DSM_DEV_MAGIC;
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return dsm_dev;
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}
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#endif /* if defined(PIOS_INCLUDE_FREERTOS) */
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/* Validate DSM device descriptor */
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static bool PIOS_DSM_Validate(struct pios_dsm_dev *dsm_dev)
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{
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return dsm_dev->magic == PIOS_DSM_DEV_MAGIC;
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}
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/* Try to bind DSMx satellite using specified number of pulses */
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static void PIOS_DSM_Bind(struct pios_dsm_dev *dsm_dev, uint8_t bind)
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{
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const struct pios_dsm_cfg *cfg = dsm_dev->cfg;
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GPIO_InitTypeDef GPIO_InitStructure = cfg->bind.init;
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GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
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/* just to limit bind pulses */
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if (bind > 10) {
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bind = 10;
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}
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GPIO_Init(cfg->bind.gpio, &cfg->bind.init);
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/* RX line, set high */
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GPIO_SetBits(cfg->bind.gpio, cfg->bind.init.GPIO_Pin);
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/* Wait until the bind window opens. */
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while (PIOS_DELAY_GetuS() < DSM_BIND_MIN_DELAY_US) {
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;
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}
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for (int i = 0; i < bind; i++) {
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/* RX line, drive low for 120us */
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GPIO_ResetBits(cfg->bind.gpio, cfg->bind.init.GPIO_Pin);
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PIOS_DELAY_WaituS(120);
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/* RX line, drive high for 120us */
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GPIO_SetBits(cfg->bind.gpio, cfg->bind.init.GPIO_Pin);
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PIOS_DELAY_WaituS(120);
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}
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/* RX line, set input and wait for data */
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GPIO_Init(cfg->bind.gpio, &GPIO_InitStructure);
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}
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/* Reset channels in case of lost signal or explicit failsafe receiver flag */
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static void PIOS_DSM_ResetChannels(struct pios_dsm_dev *dsm_dev)
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{
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struct pios_dsm_state *state = &(dsm_dev->state);
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for (int i = 0; i < PIOS_DSM_NUM_INPUTS; i++) {
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state->channel_data[i] = PIOS_RCVR_TIMEOUT;
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}
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}
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/* Reset DSM receiver state */
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static void PIOS_DSM_ResetState(struct pios_dsm_dev *dsm_dev)
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{
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struct pios_dsm_state *state = &(dsm_dev->state);
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state->receive_timer = 0;
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state->failsafe_timer = 0;
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state->frame_found = 0;
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state->quality = 0.0f;
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state->frames_lost_last = 0;
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PIOS_DSM_ResetChannels(dsm_dev);
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}
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/**
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* Check and unroll complete frame data.
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* \output 0 frame data accepted
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* \output -1 frame error found
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*/
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static int PIOS_DSM_UnrollChannels(struct pios_dsm_dev *dsm_dev)
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{
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struct pios_dsm_state *state = &(dsm_dev->state);
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/* Fix resolution for detection. */
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static uint8_t resolution = 11;
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uint32_t channel_log = 0;
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// *** UNTESTED CODE ***
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#ifdef DSM_LINK_QUALITY
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/* increment the lost frame counter */
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uint8_t frames_lost = state->received_data[0];
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/* We only get a lost frame count when the next good frame comes in */
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/* Present quality as a weighted average of good frames */
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/* First consider the bad frames */
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for (int i = 0; i < frames_lost - state->frames_lost_last; i++) {
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state->quality = (state->quality * (DSM_FL_WEIGHTED_AVE - 1)) /
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DSM_FL_WEIGHTED_AVE;
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}
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/* And now the good frame */
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state->quality = ((state->quality * (DSM_FL_WEIGHTED_AVE - 1)) +
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100) / DSM_FL_WEIGHTED_AVE;
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state->frames_lost_last = frames_lost;
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#endif /* DSM_LINK_QUALITY */
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/* unroll channels */
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uint8_t *s = &(state->received_data[2]);
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uint16_t mask = (resolution == 10) ? 0x03ff : 0x07ff;
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for (int i = 0; i < DSM_CHANNELS_PER_FRAME; i++) {
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uint16_t word = ((uint16_t)s[0] << 8) | s[1];
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s += 2;
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/* skip empty channel slot */
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if (word == 0xffff) {
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continue;
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}
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/* minimal data validation */
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if ((i > 0) && (word & DSM_2ND_FRAME_MASK)) {
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/* invalid frame data, ignore rest of the frame */
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goto stream_error;
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}
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/* extract and save the channel value */
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uint8_t channel_num = (word >> resolution) & 0x0f;
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if (channel_num < PIOS_DSM_NUM_INPUTS) {
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if (channel_log & (1 << channel_num)) {
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/* Found duplicate. This should happen when in 11 bit */
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/* mode and the data is 10 bits */
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if (resolution == 10) {
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return -1;
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}
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resolution = 10;
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return PIOS_DSM_UnrollChannels(dsm_dev);
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}
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if ((channel_log & 0xFF) == 0x55) {
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/* This pattern indicates 10 bit pattern */
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if (resolution == 11) {
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return -1;
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}
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resolution = 11;
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return PIOS_DSM_UnrollChannels(dsm_dev);
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}
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state->channel_data[channel_num] = (word & mask);
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/* keep track of this channel */
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channel_log |= (1 << channel_num);
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}
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}
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/* all channels processed */
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return 0;
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stream_error:
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/* either DSM2 selected with DSMX stream found, or vice-versa */
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return -1;
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}
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/* Update decoder state processing input byte from the DSMx stream */
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static void PIOS_DSM_UpdateState(struct pios_dsm_dev *dsm_dev, uint8_t byte)
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{
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struct pios_dsm_state *state = &(dsm_dev->state);
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if (state->frame_found) {
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/* receiving the data frame */
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if (state->byte_count < DSM_FRAME_LENGTH) {
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/* store next byte */
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state->received_data[state->byte_count++] = byte;
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if (state->byte_count == DSM_FRAME_LENGTH) {
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/* full frame received - process and wait for new one */
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if (!PIOS_DSM_UnrollChannels(dsm_dev)) {
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/* data looking good */
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state->failsafe_timer = 0;
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}
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/* prepare for the next frame */
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state->frame_found = 0;
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}
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}
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}
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}
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/* Initialise DSM receiver interface */
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int32_t PIOS_DSM_Init(uint32_t *dsm_id,
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const struct pios_dsm_cfg *cfg,
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const struct pios_com_driver *driver,
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uint32_t lower_id,
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uint8_t bind)
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{
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PIOS_DEBUG_Assert(dsm_id);
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PIOS_DEBUG_Assert(cfg);
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PIOS_DEBUG_Assert(driver);
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struct pios_dsm_dev *dsm_dev;
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dsm_dev = (struct pios_dsm_dev *)PIOS_DSM_Alloc();
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if (!dsm_dev) {
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return -1;
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}
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/* Bind the configuration to the device instance */
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dsm_dev->cfg = cfg;
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/* Bind the receiver if requested */
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if (bind) {
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PIOS_DSM_Bind(dsm_dev, bind);
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}
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PIOS_DSM_ResetState(dsm_dev);
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*dsm_id = (uint32_t)dsm_dev;
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/* Set comm driver callback */
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(driver->bind_rx_cb)(lower_id, PIOS_DSM_RxInCallback, *dsm_id);
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if (!PIOS_RTC_RegisterTickCallback(PIOS_DSM_Supervisor, *dsm_id)) {
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PIOS_DEBUG_Assert(0);
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}
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return 0;
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}
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/* Comm byte received callback */
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static uint16_t PIOS_DSM_RxInCallback(uint32_t context,
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uint8_t *buf,
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uint16_t buf_len,
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uint16_t *headroom,
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bool *need_yield)
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{
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struct pios_dsm_dev *dsm_dev = (struct pios_dsm_dev *)context;
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bool valid = PIOS_DSM_Validate(dsm_dev);
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PIOS_Assert(valid);
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/* process byte(s) and clear receive timer */
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for (uint8_t i = 0; i < buf_len; i++) {
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PIOS_DSM_UpdateState(dsm_dev, buf[i]);
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dsm_dev->state.receive_timer = 0;
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}
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/* Always signal that we can accept another byte */
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if (headroom) {
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*headroom = DSM_FRAME_LENGTH;
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}
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/* We never need a yield */
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*need_yield = false;
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/* Always indicate that all bytes were consumed */
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return buf_len;
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}
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/**
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* Get the value of an input channel
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* \param[in] channel Number of the channel desired (zero based)
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* \output PIOS_RCVR_INVALID channel not available
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* \output PIOS_RCVR_TIMEOUT failsafe condition or missing receiver
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* \output >=0 channel value
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*/
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static int32_t PIOS_DSM_Get(uint32_t rcvr_id, uint8_t channel)
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{
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struct pios_dsm_dev *dsm_dev = (struct pios_dsm_dev *)rcvr_id;
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if (!PIOS_DSM_Validate(dsm_dev)) {
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return PIOS_RCVR_INVALID;
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}
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/* return error if channel is not available */
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if (channel >= PIOS_DSM_NUM_INPUTS) {
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return PIOS_RCVR_INVALID;
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}
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/* may also be PIOS_RCVR_TIMEOUT set by other function */
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return dsm_dev->state.channel_data[channel];
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}
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/**
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* Input data supervisor is called periodically and provides
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* two functions: frame syncing and failsafe triggering.
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*
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* DSM frames come at 11ms or 22ms rate at 115200bps.
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* RTC timer is running at 625Hz (1.6ms). So with divider 5 it gives
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* 8ms pause between frames which is good for both DSM frame rates.
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*
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* Data receive function must clear the receive_timer to confirm new
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* data reception. If no new data received in 100ms, we must call the
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* failsafe function which clears all channels.
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*/
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static void PIOS_DSM_Supervisor(uint32_t dsm_id)
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{
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struct pios_dsm_dev *dsm_dev = (struct pios_dsm_dev *)dsm_id;
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bool valid = PIOS_DSM_Validate(dsm_dev);
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PIOS_Assert(valid);
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struct pios_dsm_state *state = &(dsm_dev->state);
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/* waiting for new frame if no bytes were received in 8ms */
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if (++state->receive_timer > 4) {
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state->frame_found = 1;
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state->byte_count = 0;
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state->receive_timer = 0;
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}
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/* activate failsafe if no frames have arrived in 102.4ms */
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if (++state->failsafe_timer > 64) {
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PIOS_DSM_ResetChannels(dsm_dev);
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state->failsafe_timer = 0;
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}
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}
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static uint8_t PIOS_DSM_Quality_Get(uint32_t dsm_id)
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{
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struct pios_dsm_dev *dsm_dev = (struct pios_dsm_dev *)dsm_id;
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bool valid = PIOS_DSM_Validate(dsm_dev);
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PIOS_Assert(valid);
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struct pios_dsm_state *state = &(dsm_dev->state);
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return (uint8_t)(state->quality + 0.5f);
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}
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#endif /* PIOS_INCLUDE_DSM */
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/**
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* @}
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* @}
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*/
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