betaflight/src/drivers/pwm_rx.c

#include <stdbool.h>
#include <stdint.h>

#include <stdlib.h>

#include "platform.h"

#include "gpio_common.h"
#include "timer_common.h"

#include "failsafe.h" // FIXME dependency into the main code from a driver

#include "pwm_mapping.h"

#include "pwm_rx.h"

failsafe_t *failsafe;
failsafeConfig_t *failsafeConfig;

void pwmICConfig(TIM_TypeDef *tim, uint8_t channel, uint16_t polarity); // from pwm_output.c

typedef enum {
	INPUT_MODE_PPM,
	INPUT_MODE_PWM,
} pwmInputMode_t;

typedef struct {
    pwmInputMode_t mode;
    uint8_t channel; // only used for pwm, ignored by ppm

    uint8_t state;
    captureCompare_t rise;
    captureCompare_t fall;
    captureCompare_t capture;

    const timerHardware_t *timerHardware;
} pwmInputPort_t;

static pwmInputPort_t pwmInputPorts[MAX_PWM_INPUT_PORTS];

static uint16_t captures[MAX_PWM_INPUT_PORTS];

static void failsafeCheck(uint8_t channel, uint16_t pulseDuration)
{
    static uint8_t goodChannelMask;

    if (channel < 4 && pulseDuration > failsafeConfig->failsafe_detect_threshold)
        goodChannelMask |= (1 << channel);       // if signal is valid - mark channel as OK
    if (goodChannelMask == 0x0F) {               // If first four channels have good pulses, clear FailSafe counter
        goodChannelMask = 0;
        failsafe->vTable->validDataReceived();
    }
}

static void ppmCallback(uint8_t port, captureCompare_t capture)
{
    int32_t diff;
    static captureCompare_t now;
    static captureCompare_t last = 0;

    static uint8_t chan = 0;

    last = now;
    now = capture;
    diff = now - last;

    if (diff > 2700) { // Per http://www.rcgroups.com/forums/showpost.php?p=21996147&postcount=3960 "So, if you use 2.5ms or higher as being the reset for the PPM stream start, you will be fine. I use 2.7ms just to be safe."
        chan = 0;
    } else {
        if (diff > PULSE_MIN && diff < PULSE_MAX && chan < MAX_PWM_INPUT_PORTS) {   // 750 to 2250 ms is our 'valid' channel range
            captures[chan] = diff;
            failsafeCheck(chan, diff);
        }
        chan++;
    }
}

static void pwmCallback(uint8_t port, captureCompare_t capture)
{
	pwmInputPort_t *pwmInputPort = &pwmInputPorts[port];
	const timerHardware_t *timerHardware = pwmInputPort->timerHardware;

    if (pwmInputPort->state == 0) {
        pwmInputPort->rise = capture;
        pwmInputPort->state = 1;
        pwmICConfig(timerHardware->tim, timerHardware->channel, TIM_ICPolarity_Falling);
    } else {
        pwmInputPort->fall = capture;
        // compute capture
        pwmInputPort->capture = pwmInputPort->fall - pwmInputPort->rise;
        if (pwmInputPort->capture > PULSE_MIN && pwmInputPort->capture < PULSE_MAX) { // valid pulse width
            captures[pwmInputPort->channel] = pwmInputPort->capture;
            failsafeCheck(pwmInputPort->channel, pwmInputPort->capture);
        }
        // switch state
        pwmInputPort->state = 0;
        pwmICConfig(timerHardware->tim, timerHardware->channel, TIM_ICPolarity_Rising);
    }
}

static void pwmGPIOConfig(GPIO_TypeDef *gpio, uint32_t pin, GPIO_Mode mode)
{
    gpio_config_t cfg;

    cfg.pin = pin;
    cfg.mode = mode;
    cfg.speed = Speed_2MHz;
    gpioInit(gpio, &cfg);
}

void pwmICConfig(TIM_TypeDef *tim, uint8_t channel, uint16_t polarity)
{
    TIM_ICInitTypeDef  TIM_ICInitStructure;

    TIM_ICStructInit(&TIM_ICInitStructure);
    TIM_ICInitStructure.TIM_Channel = channel;
    TIM_ICInitStructure.TIM_ICPolarity = polarity;
    TIM_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI;
    TIM_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1;
    TIM_ICInitStructure.TIM_ICFilter = 0x0;

    TIM_ICInit(tim, &TIM_ICInitStructure);
}

void pwmInConfig(uint8_t timerIndex, uint8_t channel)
{
    pwmInputPort_t *p = &pwmInputPorts[channel];

    const timerHardware_t *timerHardwarePtr = &(timerHardware[timerIndex]);

    p->channel = channel;
    p->mode = INPUT_MODE_PWM;
    p->timerHardware = timerHardwarePtr;

    pwmGPIOConfig(timerHardwarePtr->gpio, timerHardwarePtr->pin, timerHardwarePtr->gpioInputMode);
    pwmICConfig(timerHardwarePtr->tim, timerHardwarePtr->channel, TIM_ICPolarity_Rising);

    timerConfigure(timerHardwarePtr, 0xFFFF, PWM_TIMER_MHZ);
    configureTimerCaptureCompareInterrupt(timerHardwarePtr, channel, pwmCallback);
}

#define UNUSED_PPM_TIMER_REFERENCE 0
#define FIRST_PWM_PORT 0

void ppmInConfig(uint8_t timerIndex)
{
    pwmInputPort_t *p = &pwmInputPorts[FIRST_PWM_PORT];

    const timerHardware_t *timerHardwarePtr = &(timerHardware[timerIndex]);

    p->mode = INPUT_MODE_PPM;
    p->timerHardware = timerHardwarePtr;

    pwmGPIOConfig(timerHardwarePtr->gpio, timerHardwarePtr->pin, timerHardwarePtr->gpioInputMode);
    pwmICConfig(timerHardwarePtr->tim, timerHardwarePtr->channel, TIM_ICPolarity_Rising);

    timerConfigure(timerHardwarePtr, 0xFFFF, PWM_TIMER_MHZ);
    configureTimerCaptureCompareInterrupt(timerHardwarePtr, UNUSED_PPM_TIMER_REFERENCE, ppmCallback);
}

uint16_t pwmRead(uint8_t channel)
{
    return captures[channel];
}

void pwmRxInit(failsafe_t *initialFailsafe, failsafeConfig_t *initialFailsafeConfig)
{
    failsafe = initialFailsafe;
    failsafeConfig = initialFailsafeConfig;
}