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LibrePilot/flight/PiOS/STM32F10x/pios_ppm.c
Stacey Sheldon 5ca4ec7934 ppm: adjust min frame pulse width for 8ch x 18ms frames
All channels at max when using the FrSKY 4ch D4FR in PPM
mode results in the frame pulse shrinking well below our
threshold of 3800us and we lose frame.

With all 8 channels at max, the frame pulse becomes
indistinguishable from the other channels.  Using all 8
channels with the FrSKY in PPM mode is NOT recommended
even after this change.

Recommend using at most 7 active channels in this mode so
we can still find the frame pulse.
2012-04-16 14:33:28 -04:00

358 lines
9.8 KiB
C

/**
******************************************************************************
* @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) 2010.
* @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
*/
/* Project Includes */
#include "pios.h"
#include "pios_ppm_priv.h"
#if defined(PIOS_INCLUDE_PPM)
/* 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 3000 // 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] = 0;
ppm_dev->CaptureValueNewFrame[i] = 0;
}
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
* \output -1 Channel not available
* \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
/**
* @}
* @}
*/