/**
******************************************************************************
* @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"
// *** UNTESTED CODE ***
#undef DSM_LINK_QUALITY
#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 uint8_t PIOS_DSM_Quality_Get(uint32_t rcvr_id);
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,
.get_quality = PIOS_DSM_Quality_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;
uint8_t frames_lost_last;
float quality;
};
/* With an DSM frame rate of 11ms (90Hz) averaging over 18 samples
* gives about a 200ms response.
*/
#define DSM_FL_WEIGHTED_AVE 18
struct pios_dsm_dev {
enum pios_dsm_dev_magic magic;
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 stm32_gpio *rxpin, uint8_t bind)
{
GPIO_InitTypeDef bindInit = {
.GPIO_Pin = rxpin->init.GPIO_Pin,
.GPIO_Speed = GPIO_Speed_2MHz,
#ifdef STM32F10X
.GPIO_Mode = GPIO_Mode_Out_PP,
#else
.GPIO_Mode = GPIO_Mode_OUT,
.GPIO_OType = GPIO_OType_PP,
.GPIO_PuPd = GPIO_PuPd_NOPULL
#endif
};
GPIO_Init(rxpin->gpio, &bindInit);
/* RX line, set high */
GPIO_SetBits(rxpin->gpio, rxpin->init.GPIO_Pin);
/* Wait until the bind window opens. */
while (PIOS_DELAY_GetuS() < DSM_BIND_MIN_DELAY_US) {
;
}
/* just to limit bind pulses */
if (bind > 10) {
bind = 10;
}
for (int i = 0; i < bind; i++) {
/* RX line, drive low for 120us */
GPIO_ResetBits(rxpin->gpio, rxpin->init.GPIO_Pin);
PIOS_DELAY_WaituS(120);
/* RX line, drive high for 120us */
GPIO_SetBits(rxpin->gpio, rxpin->init.GPIO_Pin);
PIOS_DELAY_WaituS(120);
}
/* RX line, set input and wait for data */
GPIO_Init(rxpin->gpio, (GPIO_InitTypeDef *)&rxpin->init);
}
/* 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;
state->quality = 0.0f;
state->frames_lost_last = 0;
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);
/* Fix resolution for detection. */
static uint8_t resolution = 11;
uint32_t channel_log = 0;
// *** UNTESTED CODE ***
#ifdef DSM_LINK_QUALITY
/* increment the lost frame counter */
uint8_t frames_lost = state->received_data[0];
/* We only get a lost frame count when the next good frame comes in */
/* Present quality as a weighted average of good frames */
/* First consider the bad frames */
for (int i = 0; i < frames_lost - state->frames_lost_last; i++) {
state->quality = (state->quality * (DSM_FL_WEIGHTED_AVE - 1)) /
DSM_FL_WEIGHTED_AVE;
}
/* And now the good frame */
state->quality = ((state->quality * (DSM_FL_WEIGHTED_AVE - 1)) +
100) / DSM_FL_WEIGHTED_AVE;
state->frames_lost_last = frames_lost;
#endif /* DSM_LINK_QUALITY */
/* 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) {
if (channel_log & (1 << channel_num)) {
/* Found duplicate. This should happen when in 11 bit */
/* mode and the data is 10 bits */
if (resolution == 10) {
return -1;
}
resolution = 10;
return PIOS_DSM_UnrollChannels(dsm_dev);
}
if ((channel_log & 0xFF) == 0x55) {
/* This pattern indicates 10 bit pattern */
if (resolution == 11) {
return -1;
}
resolution = 11;
return PIOS_DSM_UnrollChannels(dsm_dev);
}
state->channel_data[channel_num] = (word & mask);
/* keep track of this channel */
channel_log |= (1 << channel_num);
}
}
/* 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_com_driver *driver,
uint32_t lower_id,
uint8_t bind)
{
PIOS_DEBUG_Assert(dsm_id);
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 receiver if requested */
if (bind) {
struct stm32_gpio rxpin;
PIOS_DEBUG_Assert(driver->ioctl);
if ((driver->ioctl)(lower_id, PIOS_IOCTL_USART_GET_DSMBIND, &rxpin) == 0) {
PIOS_DSM_Bind(&rxpin, bind);
}
}
PIOS_DSM_ResetState(dsm_dev);
*dsm_id = (uint32_t)dsm_dev;
/* Set comm driver parameters */
PIOS_DEBUG_Assert(driver->set_config);
driver->set_config(lower_id, PIOS_COM_Word_length_8b, PIOS_COM_Parity_No, PIOS_COM_StopBits_1, 115200);
/* Set irq priority */
if (driver->ioctl) {
uint8_t irq_prio = PIOS_IRQ_PRIO_HIGH;
driver->ioctl(lower_id, PIOS_IOCTL_USART_SET_IRQ_PRIO, &irq_prio);
}
/* 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;
}
}
static uint8_t PIOS_DSM_Quality_Get(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);
return (uint8_t)(state->quality + 0.5f);
}
#endif /* PIOS_INCLUDE_DSM */
/**
* @}
* @}
*/