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LibrePilot/flight/PiOS/STM32F4xx/pios_ppm.c

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/**
******************************************************************************
* @addtogroup PIOS PIOS Core hardware abstraction layer
* @{
* @addtogroup PIOS_PPM PPM Input Functions
* @brief Code to measure PPM input and seperate into channels
* @{
*
* @file pios_ppm.c
* @author The OpenPilot Team, http://www.openpilot.org Copyright (C) 2012.
* @brief PPM Input functions (STM32 dependent)
* @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_PPM
#include "pios_ppm_priv.h"
/* Provide a RCVR driver */
static int32_t PIOS_PPM_Get(uint32_t rcvr_id, uint8_t channel);
const struct pios_rcvr_driver pios_ppm_rcvr_driver = {
.read = PIOS_PPM_Get,
};
#define PIOS_PPM_IN_MIN_NUM_CHANNELS 4
#define PIOS_PPM_IN_MAX_NUM_CHANNELS PIOS_PPM_NUM_INPUTS
#define PIOS_PPM_STABLE_CHANNEL_COUNT 25 // frames
#define PIOS_PPM_IN_MIN_SYNC_PULSE_US 3800 // microseconds
#define PIOS_PPM_IN_MIN_CHANNEL_PULSE_US 750 // microseconds
#define PIOS_PPM_IN_MAX_CHANNEL_PULSE_US 2250 // microseconds
/* Local Variables */
static TIM_ICInitTypeDef TIM_ICInitStructure;
static void PIOS_PPM_Supervisor(uint32_t ppm_id);
enum pios_ppm_dev_magic {
PIOS_PPM_DEV_MAGIC = 0xee014d8b,
};
struct pios_ppm_dev {
enum pios_ppm_dev_magic magic;
const struct pios_ppm_cfg * cfg;
uint8_t PulseIndex;
uint32_t PreviousTime;
uint32_t CurrentTime;
uint32_t DeltaTime;
uint32_t CaptureValue[PIOS_PPM_IN_MAX_NUM_CHANNELS];
uint32_t CaptureValueNewFrame[PIOS_PPM_IN_MAX_NUM_CHANNELS];
uint32_t LargeCounter;
int8_t NumChannels;
int8_t NumChannelsPrevFrame;
uint8_t NumChannelCounter;
uint8_t supv_timer;
bool Tracking;
bool Fresh;
};
static bool PIOS_PPM_validate(struct pios_ppm_dev * ppm_dev)
{
return (ppm_dev->magic == PIOS_PPM_DEV_MAGIC);
}
#if defined(PIOS_INCLUDE_FREERTOS)
static struct pios_ppm_dev * PIOS_PPM_alloc(void)
{
struct pios_ppm_dev * ppm_dev;
ppm_dev = (struct pios_ppm_dev *)pvPortMalloc(sizeof(*ppm_dev));
if (!ppm_dev) return(NULL);
ppm_dev->magic = PIOS_PPM_DEV_MAGIC;
return(ppm_dev);
}
#else
static struct pios_ppm_dev pios_ppm_devs[PIOS_PPM_MAX_DEVS];
static uint8_t pios_ppm_num_devs;
static struct pios_ppm_dev * PIOS_PPM_alloc(void)
{
struct pios_ppm_dev * ppm_dev;
if (pios_ppm_num_devs >= PIOS_PPM_MAX_DEVS) {
return (NULL);
}
ppm_dev = &pios_ppm_devs[pios_ppm_num_devs++];
ppm_dev->magic = PIOS_PPM_DEV_MAGIC;
return (ppm_dev);
}
#endif
static void PIOS_PPM_tim_overflow_cb (uint32_t id, uint32_t context, uint8_t channel, uint16_t count);
static void PIOS_PPM_tim_edge_cb (uint32_t id, uint32_t context, uint8_t channel, uint16_t count);
const static struct pios_tim_callbacks tim_callbacks = {
.overflow = PIOS_PPM_tim_overflow_cb,
.edge = PIOS_PPM_tim_edge_cb,
};
extern int32_t PIOS_PPM_Init(uint32_t * ppm_id, const struct pios_ppm_cfg * cfg)
{
PIOS_DEBUG_Assert(ppm_id);
PIOS_DEBUG_Assert(cfg);
struct pios_ppm_dev * ppm_dev;
ppm_dev = (struct pios_ppm_dev *) PIOS_PPM_alloc();
if (!ppm_dev) goto out_fail;
/* Bind the configuration to the device instance */
ppm_dev->cfg = cfg;
/* Set up the state variables */
ppm_dev->PulseIndex = 0;
ppm_dev->PreviousTime = 0;
ppm_dev->CurrentTime = 0;
ppm_dev->DeltaTime = 0;
ppm_dev->LargeCounter = 0;
ppm_dev->NumChannels = -1;
ppm_dev->NumChannelsPrevFrame = -1;
ppm_dev->NumChannelCounter = 0;
ppm_dev->Tracking = false;
ppm_dev->Fresh = false;
for (uint8_t i = 0; i < PIOS_PPM_IN_MAX_NUM_CHANNELS; i++) {
/* Flush counter variables */
ppm_dev->CaptureValue[i] = PIOS_RCVR_TIMEOUT;
ppm_dev->CaptureValueNewFrame[i] = PIOS_RCVR_TIMEOUT;
}
uint32_t tim_id;
if (PIOS_TIM_InitChannels(&tim_id, cfg->channels, cfg->num_channels, &tim_callbacks, (uint32_t)ppm_dev)) {
return -1;
}
/* Configure the channels to be in capture/compare mode */
for (uint8_t i = 0; i < cfg->num_channels; i++) {
const struct pios_tim_channel * chan = &cfg->channels[i];
/* Configure timer for input capture */
TIM_ICInitTypeDef TIM_ICInitStructure = cfg->tim_ic_init;
TIM_ICInitStructure.TIM_Channel = chan->timer_chan;
TIM_ICInit(chan->timer, &TIM_ICInitStructure);
/* Enable the Capture Compare Interrupt Request */
switch (chan->timer_chan) {
case TIM_Channel_1:
TIM_ITConfig(chan->timer, TIM_IT_CC1 | TIM_IT_Update, ENABLE);
break;
case TIM_Channel_2:
TIM_ITConfig(chan->timer, TIM_IT_CC2 | TIM_IT_Update, ENABLE);
break;
case TIM_Channel_3:
TIM_ITConfig(chan->timer, TIM_IT_CC3 | TIM_IT_Update, ENABLE);
break;
case TIM_Channel_4:
TIM_ITConfig(chan->timer, TIM_IT_CC4 | TIM_IT_Update, ENABLE);
break;
}
}
/* Setup local variable which stays in this scope */
/* Doing this here and using a local variable saves doing it in the ISR */
TIM_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI;
TIM_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1;
TIM_ICInitStructure.TIM_ICFilter = 0x0;
if (!PIOS_RTC_RegisterTickCallback(PIOS_PPM_Supervisor, (uint32_t)ppm_dev)) {
PIOS_DEBUG_Assert(0);
}
*ppm_id = (uint32_t)ppm_dev;
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_PPM_Get(uint32_t rcvr_id, uint8_t channel)
{
struct pios_ppm_dev * ppm_dev = (struct pios_ppm_dev *)rcvr_id;
if (!PIOS_PPM_validate(ppm_dev)) {
/* Invalid device specified */
return PIOS_RCVR_INVALID;
}
if (channel >= PIOS_PPM_IN_MAX_NUM_CHANNELS) {
/* Channel out of range */
return PIOS_RCVR_INVALID;
}
return ppm_dev->CaptureValue[channel];
}
static void PIOS_PPM_tim_overflow_cb (uint32_t tim_id, uint32_t context, uint8_t channel, uint16_t count)
{
struct pios_ppm_dev * ppm_dev = (struct pios_ppm_dev *)context;
if (!PIOS_PPM_validate(ppm_dev)) {
/* Invalid device specified */
return;
}
ppm_dev->LargeCounter += count;
return;
}
static void PIOS_PPM_tim_edge_cb (uint32_t tim_id, uint32_t context, uint8_t chan_idx, uint16_t count)
{
/* Recover our device context */
struct pios_ppm_dev * ppm_dev = (struct pios_ppm_dev *)context;
if (!PIOS_PPM_validate(ppm_dev)) {
/* Invalid device specified */
return;
}
if (chan_idx >= ppm_dev->cfg->num_channels) {
/* Channel out of range */
return;
}
/* Shift the last measurement out */
ppm_dev->PreviousTime = ppm_dev->CurrentTime;
/* Grab the new count */
ppm_dev->CurrentTime = count;
/* Convert to 32-bit timer result */
ppm_dev->CurrentTime += ppm_dev->LargeCounter;
/* Capture computation */
ppm_dev->DeltaTime = ppm_dev->CurrentTime - ppm_dev->PreviousTime;
ppm_dev->PreviousTime = ppm_dev->CurrentTime;
/* Sync pulse detection */
if (ppm_dev->DeltaTime > PIOS_PPM_IN_MIN_SYNC_PULSE_US) {
if (ppm_dev->PulseIndex == ppm_dev->NumChannelsPrevFrame
&& ppm_dev->PulseIndex >= PIOS_PPM_IN_MIN_NUM_CHANNELS
&& ppm_dev->PulseIndex <= PIOS_PPM_IN_MAX_NUM_CHANNELS)
{
/* If we see n simultaneous frames of the same
number of channels we save it as our frame size */
if (ppm_dev->NumChannelCounter < PIOS_PPM_STABLE_CHANNEL_COUNT)
ppm_dev->NumChannelCounter++;
else
ppm_dev->NumChannels = ppm_dev->PulseIndex;
} else {
ppm_dev->NumChannelCounter = 0;
}
/* Check if the last frame was well formed */
if (ppm_dev->PulseIndex == ppm_dev->NumChannels && ppm_dev->Tracking) {
/* The last frame was well formed */
for (uint32_t i = 0; i < ppm_dev->NumChannels; i++) {
ppm_dev->CaptureValue[i] = ppm_dev->CaptureValueNewFrame[i];
}
for (uint32_t i = ppm_dev->NumChannels;
i < PIOS_PPM_IN_MAX_NUM_CHANNELS; i++) {
ppm_dev->CaptureValue[i] = PIOS_RCVR_TIMEOUT;
}
}
ppm_dev->Fresh = true;
ppm_dev->Tracking = true;
ppm_dev->NumChannelsPrevFrame = ppm_dev->PulseIndex;
ppm_dev->PulseIndex = 0;
/* We rely on the supervisor to set CaptureValue to invalid
if no valid frame is found otherwise we ride over it */
} else if (ppm_dev->Tracking) {
/* Valid pulse duration 0.75 to 2.5 ms*/
if (ppm_dev->DeltaTime > PIOS_PPM_IN_MIN_CHANNEL_PULSE_US
&& ppm_dev->DeltaTime < PIOS_PPM_IN_MAX_CHANNEL_PULSE_US
&& ppm_dev->PulseIndex < PIOS_PPM_IN_MAX_NUM_CHANNELS) {
ppm_dev->CaptureValueNewFrame[ppm_dev->PulseIndex] = ppm_dev->DeltaTime;
ppm_dev->PulseIndex++;
} else {
/* Not a valid pulse duration */
ppm_dev->Tracking = false;
for (uint32_t i = 0; i < PIOS_PPM_IN_MAX_NUM_CHANNELS ; i++) {
ppm_dev->CaptureValueNewFrame[i] = PIOS_RCVR_TIMEOUT;
}
}
}
}
static void PIOS_PPM_Supervisor(uint32_t ppm_id) {
/* Recover our device context */
struct pios_ppm_dev * ppm_dev = (struct pios_ppm_dev *)ppm_id;
if (!PIOS_PPM_validate(ppm_dev)) {
/* Invalid device specified */
return;
}
/*
* RTC runs at 625Hz so divide down the base rate so
* that this loop runs at 25Hz.
*/
if(++(ppm_dev->supv_timer) < 25) {
return;
}
ppm_dev->supv_timer = 0;
if (!ppm_dev->Fresh) {
ppm_dev->Tracking = false;
for (int32_t i = 0; i < PIOS_PPM_IN_MAX_NUM_CHANNELS ; i++) {
ppm_dev->CaptureValue[i] = PIOS_RCVR_TIMEOUT;
ppm_dev->CaptureValueNewFrame[i] = PIOS_RCVR_TIMEOUT;
}
}
ppm_dev->Fresh = false;
}
#endif /* PIOS_INCLUDE_PPM */
/**
* @}
* @}
*/
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