/**
******************************************************************************
* @addtogroup PIOS PIOS Core hardware abstraction layer
* @{
* @addtogroup PIOS_DSM Spektrum/JR DSMx satellite receiver functions
* @brief Code to bind and read Spektrum/JR DSMx satellite receiver serial stream
* @{
*
* @file pios_dsm.c
* @author The OpenPilot Team, http://www.openpilot.org Copyright (C) 2012.
* @brief Code bind and read Spektrum/JR DSMx satellite 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_DSM
#include "pios_dsm_priv.h"
#ifndef PIOS_INCLUDE_RTC
#error PIOS_INCLUDE_RTC must be used to use DSM
#endif
/* Forward Declarations */
static int32_t PIOS_DSM_Get(uint32_t rcvr_id, uint8_t channel);
static uint16_t PIOS_DSM_RxInCallback(uint32_t context,
uint8_t *buf,
uint16_t buf_len,
uint16_t *headroom,
bool *need_yield);
static void PIOS_DSM_Supervisor(uint32_t dsm_id);
/* Local Variables */
const struct pios_rcvr_driver pios_dsm_rcvr_driver = {
.read = PIOS_DSM_Get,
};
enum pios_dsm_dev_magic {
PIOS_DSM_DEV_MAGIC = 0x44534d78,
};
struct pios_dsm_state {
uint16_t channel_data[PIOS_DSM_NUM_INPUTS];
uint8_t received_data[DSM_FRAME_LENGTH];
uint8_t receive_timer;
uint8_t failsafe_timer;
uint8_t frame_found;
uint8_t byte_count;
#ifdef DSM_LOST_FRAME_COUNTER
uint8_t frames_lost_last;
uint16_t frames_lost;
#endif
};
struct pios_dsm_dev {
enum pios_dsm_dev_magic magic;
const struct pios_dsm_cfg *cfg;
enum pios_dsm_proto proto;
struct pios_dsm_state state;
};
/* Allocate DSM device descriptor */
#if defined(PIOS_INCLUDE_FREERTOS)
static struct pios_dsm_dev *PIOS_DSM_Alloc(void)
{
struct pios_dsm_dev *dsm_dev;
dsm_dev = (struct pios_dsm_dev *)pios_malloc(sizeof(*dsm_dev));
if (!dsm_dev) {
return NULL;
}
dsm_dev->magic = PIOS_DSM_DEV_MAGIC;
return dsm_dev;
}
#else
static struct pios_dsm_dev pios_dsm_devs[PIOS_DSM_MAX_DEVS];
static uint8_t pios_dsm_num_devs;
static struct pios_dsm_dev *PIOS_DSM_Alloc(void)
{
struct pios_dsm_dev *dsm_dev;
if (pios_dsm_num_devs >= PIOS_DSM_MAX_DEVS) {
return NULL;
}
dsm_dev = &pios_dsm_devs[pios_dsm_num_devs++];
dsm_dev->magic = PIOS_DSM_DEV_MAGIC;
return dsm_dev;
}
#endif /* if defined(PIOS_INCLUDE_FREERTOS) */
/* Validate DSM device descriptor */
static bool PIOS_DSM_Validate(struct pios_dsm_dev *dsm_dev)
{
return dsm_dev->magic == PIOS_DSM_DEV_MAGIC;
}
/* Try to bind DSMx satellite using specified number of pulses */
static void PIOS_DSM_Bind(struct pios_dsm_dev *dsm_dev, uint8_t bind)
{
const struct pios_dsm_cfg *cfg = dsm_dev->cfg;
GPIO_InitTypeDef GPIO_InitStructure = cfg->bind.init;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
/* just to limit bind pulses */
if (bind > 10) {
bind = 10;
}
GPIO_Init(cfg->bind.gpio, &cfg->bind.init);
/* RX line, set high */
GPIO_SetBits(cfg->bind.gpio, cfg->bind.init.GPIO_Pin);
/* on CC works up to 140ms, guess bind window is around 20-140ms after power up */
PIOS_DELAY_WaitmS(60);
for (int i = 0; i < bind; i++) {
/* RX line, drive low for 120us */
GPIO_ResetBits(cfg->bind.gpio, cfg->bind.init.GPIO_Pin);
PIOS_DELAY_WaituS(120);
/* RX line, drive high for 120us */
GPIO_SetBits(cfg->bind.gpio, cfg->bind.init.GPIO_Pin);
PIOS_DELAY_WaituS(120);
}
/* RX line, set input and wait for data */
GPIO_Init(cfg->bind.gpio, &GPIO_InitStructure);
}
/* Reset channels in case of lost signal or explicit failsafe receiver flag */
static void PIOS_DSM_ResetChannels(struct pios_dsm_dev *dsm_dev)
{
struct pios_dsm_state *state = &(dsm_dev->state);
for (int i = 0; i < PIOS_DSM_NUM_INPUTS; i++) {
state->channel_data[i] = PIOS_RCVR_TIMEOUT;
}
}
/* Reset DSM receiver state */
static void PIOS_DSM_ResetState(struct pios_dsm_dev *dsm_dev)
{
struct pios_dsm_state *state = &(dsm_dev->state);
state->receive_timer = 0;
state->failsafe_timer = 0;
state->frame_found = 0;
#ifdef DSM_LOST_FRAME_COUNTER
state->frames_lost_last = 0;
state->frames_lost = 0;
#endif
PIOS_DSM_ResetChannels(dsm_dev);
}
/**
* Check and unroll complete frame data.
* \output 0 frame data accepted
* \output -1 frame error found
*/
static int PIOS_DSM_UnrollChannels(struct pios_dsm_dev *dsm_dev)
{
struct pios_dsm_state *state = &(dsm_dev->state);
uint8_t resolution;
#ifdef DSM_LOST_FRAME_COUNTER
/* increment the lost frame counter */
uint8_t frames_lost = state->received_data[0];
state->frames_lost += (frames_lost - state->frames_lost_last);
state->frames_lost_last = frames_lost;
#endif
/* check the frame type assuming master satellite stream */
uint8_t type = state->received_data[1];
switch (type) {
case 0x01:
case 0x02:
case 0x12:
/* DSM2, DSMJ stream */
if (dsm_dev->proto == PIOS_DSM_PROTO_DSM2) {
/* DSM2/DSMJ resolution is known from the header */
resolution = (type & DSM_DSM2_RES_MASK) ? 11 : 10;
} else {
/* DSMX resolution should explicitly be selected */
goto stream_error;
}
break;
case 0xA2:
case 0xB2:
/* DSMX stream */
if (dsm_dev->proto == PIOS_DSM_PROTO_DSMX10BIT) {
resolution = 10;
} else if (dsm_dev->proto == PIOS_DSM_PROTO_DSMX11BIT) {
resolution = 11;
} else {
/* DSMX resolution should explicitly be selected */
goto stream_error;
}
break;
default:
/* unknown yet data stream */
goto stream_error;
}
/* unroll channels */
uint8_t *s = &(state->received_data[2]);
uint16_t mask = (resolution == 10) ? 0x03ff : 0x07ff;
for (int i = 0; i < DSM_CHANNELS_PER_FRAME; i++) {
uint16_t word = ((uint16_t)s[0] << 8) | s[1];
s += 2;
/* skip empty channel slot */
if (word == 0xffff) {
continue;
}
/* minimal data validation */
if ((i > 0) && (word & DSM_2ND_FRAME_MASK)) {
/* invalid frame data, ignore rest of the frame */
goto stream_error;
}
/* extract and save the channel value */
uint8_t channel_num = (word >> resolution) & 0x0f;
if (channel_num < PIOS_DSM_NUM_INPUTS) {
state->channel_data[channel_num] = (word & mask);
}
}
#ifdef DSM_LOST_FRAME_COUNTER
/* put lost frames counter into the last channel for debugging */
state->channel_data[PIOS_DSM_NUM_INPUTS - 1] = state->frames_lost;
#endif
/* all channels processed */
return 0;
stream_error:
/* either DSM2 selected with DSMX stream found, or vice-versa */
return -1;
}
/* Update decoder state processing input byte from the DSMx stream */
static void PIOS_DSM_UpdateState(struct pios_dsm_dev *dsm_dev, uint8_t byte)
{
struct pios_dsm_state *state = &(dsm_dev->state);
if (state->frame_found) {
/* receiving the data frame */
if (state->byte_count < DSM_FRAME_LENGTH) {
/* store next byte */
state->received_data[state->byte_count++] = byte;
if (state->byte_count == DSM_FRAME_LENGTH) {
/* full frame received - process and wait for new one */
if (!PIOS_DSM_UnrollChannels(dsm_dev)) {
/* data looking good */
state->failsafe_timer = 0;
}
/* prepare for the next frame */
state->frame_found = 0;
}
}
}
}
/* Initialise DSM receiver interface */
int32_t PIOS_DSM_Init(uint32_t *dsm_id,
const struct pios_dsm_cfg *cfg,
const struct pios_com_driver *driver,
uint32_t lower_id,
enum pios_dsm_proto proto,
uint8_t bind)
{
PIOS_DEBUG_Assert(dsm_id);
PIOS_DEBUG_Assert(cfg);
PIOS_DEBUG_Assert(driver);
struct pios_dsm_dev *dsm_dev;
dsm_dev = (struct pios_dsm_dev *)PIOS_DSM_Alloc();
if (!dsm_dev) {
return -1;
}
/* Bind the configuration to the device instance */
dsm_dev->cfg = cfg;
dsm_dev->proto = proto;
/* Bind the receiver if requested */
if (bind) {
PIOS_DSM_Bind(dsm_dev, bind);
}
PIOS_DSM_ResetState(dsm_dev);
*dsm_id = (uint32_t)dsm_dev;
/* Set comm driver callback */
(driver->bind_rx_cb)(lower_id, PIOS_DSM_RxInCallback, *dsm_id);
if (!PIOS_RTC_RegisterTickCallback(PIOS_DSM_Supervisor, *dsm_id)) {
PIOS_DEBUG_Assert(0);
}
return 0;
}
/* Comm byte received callback */
static uint16_t PIOS_DSM_RxInCallback(uint32_t context,
uint8_t *buf,
uint16_t buf_len,
uint16_t *headroom,
bool *need_yield)
{
struct pios_dsm_dev *dsm_dev = (struct pios_dsm_dev *)context;
bool valid = PIOS_DSM_Validate(dsm_dev);
PIOS_Assert(valid);
/* process byte(s) and clear receive timer */
for (uint8_t i = 0; i < buf_len; i++) {
PIOS_DSM_UpdateState(dsm_dev, buf[i]);
dsm_dev->state.receive_timer = 0;
}
/* Always signal that we can accept another byte */
if (headroom) {
*headroom = DSM_FRAME_LENGTH;
}
/* We never need a yield */
*need_yield = false;
/* Always indicate that all bytes were consumed */
return buf_len;
}
/**
* 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_DSM_Get(uint32_t rcvr_id, uint8_t channel)
{
struct pios_dsm_dev *dsm_dev = (struct pios_dsm_dev *)rcvr_id;
if (!PIOS_DSM_Validate(dsm_dev)) {
return PIOS_RCVR_INVALID;
}
/* return error if channel is not available */
if (channel >= PIOS_DSM_NUM_INPUTS) {
return PIOS_RCVR_INVALID;
}
/* may also be PIOS_RCVR_TIMEOUT set by other function */
return dsm_dev->state.channel_data[channel];
}
/**
* Input data supervisor is called periodically and provides
* two functions: frame syncing and failsafe triggering.
*
* DSM frames come at 11ms or 22ms rate at 115200bps.
* RTC timer is running at 625Hz (1.6ms). So with divider 5 it gives
* 8ms pause between frames which is good for both DSM 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_DSM_Supervisor(uint32_t dsm_id)
{
struct pios_dsm_dev *dsm_dev = (struct pios_dsm_dev *)dsm_id;
bool valid = PIOS_DSM_Validate(dsm_dev);
PIOS_Assert(valid);
struct pios_dsm_state *state = &(dsm_dev->state);
/* waiting for new frame if no bytes were received in 8ms */
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_DSM_ResetChannels(dsm_dev);
state->failsafe_timer = 0;
}
}
#endif /* PIOS_INCLUDE_DSM */
/**
* @}
* @}
*/