motors/simple_receiver.cc

// This file has the main for the Teensy on the simple receiver board.

#include <inttypes.h>
#include <stdio.h>
#include <atomic>
#include <cmath>

#include "motors/core/kinetis.h"
#include "motors/core/time.h"
#include "motors/peripheral/adc.h"
#include "motors/peripheral/can.h"
#include "motors/peripheral/configuration.h"
#include "motors/usb/cdc.h"
#include "motors/usb/usb.h"
#include "motors/util.h"

namespace frc971 {
namespace motors {
namespace {

::std::atomic<teensy::AcmTty *> global_stdout{nullptr};

// Last width we received on each channel.
uint16_t pwm_input_widths[5];
// When we received a pulse on each channel in milliseconds.
uint32_t pwm_input_times[5];

// Returns the most recently captured value for the specified input channel
// scaled from -1 to 1, or 0 if it was captured over 100ms ago.
float convert_input_width(int channel) {
  uint16_t width;
  {
    DisableInterrupts disable_interrupts;
    if (time_after(millis(), time_add(pwm_input_times[channel], 100))) {
      return 0;
    }

    width = pwm_input_widths[channel];
  }

  // Values measured with a channel mapped to a button.
  static constexpr uint16_t kMinWidth = 4133;
  static constexpr uint16_t kMaxWidth = 7177;
  if (width < kMinWidth) {
    width = kMinWidth;
  } else if (width > kMaxWidth) {
    width = kMaxWidth;
  }
  return (static_cast<float>(2 * (width - kMinWidth)) /
          static_cast<float>(kMaxWidth - kMinWidth)) -
         1.0f;
}

// Sends a SET_RPM command to the specified VESC.
// Note that sending 6 VESC commands every 1ms doesn't quite fit in the CAN
// bandwidth.
void vesc_set_rpm(int vesc_id, float rpm) {
  const int32_t rpm_int = rpm;
  uint32_t id = CAN_EFF_FLAG;
  id |= vesc_id;
  id |= (0x03 /* SET_RPM */) << 8;
  uint8_t data[4] = {
      static_cast<uint8_t>((rpm_int >> 24) & 0xFF),
      static_cast<uint8_t>((rpm_int >> 16) & 0xFF),
      static_cast<uint8_t>((rpm_int >> 8) & 0xFF),
      static_cast<uint8_t>((rpm_int >> 0) & 0xFF),
  };
  can_send(id, data, sizeof(data), 2 + vesc_id);
}

// Sends a SET_CURRENT command to the specified VESC.
// current is in amps.
// Note that sending 6 VESC commands every 1ms doesn't quite fit in the CAN
// bandwidth.
void vesc_set_current(int vesc_id, float current) {
  const int32_t current_int = current * 1000;
  uint32_t id = CAN_EFF_FLAG;
  id |= vesc_id;
  id |= (0x01 /* SET_CURRENT */) << 8;
  uint8_t data[4] = {
      static_cast<uint8_t>((current_int >> 24) & 0xFF),
      static_cast<uint8_t>((current_int >> 16) & 0xFF),
      static_cast<uint8_t>((current_int >> 8) & 0xFF),
      static_cast<uint8_t>((current_int >> 0) & 0xFF),
  };
  can_send(id, data, sizeof(data), 2 + vesc_id);
}

void DoVescTest() {
  uint32_t time = micros();
  while (true) {
    for (int i = 0; i < 6; ++i) {
      const uint32_t end = time_add(time, 500000);
      while (true) {
        const bool done = time_after(micros(), end);
        float current;
        if (done) {
          current = -6;
        } else {
          current = 6;
        }
        vesc_set_current(i, current);
        if (done) {
          break;
        }
        delay(5);
      }
      time = end;
    }
  }
}

void DoReceiverTest2() {
  static constexpr float kMaxRpm = 10000.0f;
  while (true) {
    const bool flip = convert_input_width(2) > 0;

    {
      const float value = convert_input_width(0);

      {
        float rpm = ::std::min(0.0f, value) * kMaxRpm;
        if (flip) {
          rpm *= -1.0f;
        }
        vesc_set_rpm(0, rpm);
      }

      {
        float rpm = ::std::max(0.0f, value) * kMaxRpm;
        if (flip) {
          rpm *= -1.0f;
        }
        vesc_set_rpm(1, rpm);
      }
    }

    {
      const float value = convert_input_width(1);

      {
        float rpm = ::std::min(0.0f, value) * kMaxRpm;
        if (flip) {
          rpm *= -1.0f;
        }
        vesc_set_rpm(2, rpm);
      }

      {
        float rpm = ::std::max(0.0f, value) * kMaxRpm;
        if (flip) {
          rpm *= -1.0f;
        }
        vesc_set_rpm(3, rpm);
      }
    }

    {
      const float value = convert_input_width(4);

      {
        float rpm = ::std::min(0.0f, value) * kMaxRpm;
        if (flip) {
          rpm *= -1.0f;
        }
        vesc_set_rpm(4, rpm);
      }

      {
        float rpm = ::std::max(0.0f, value) * kMaxRpm;
        if (flip) {
          rpm *= -1.0f;
        }
        vesc_set_rpm(5, rpm);
      }
    }
    // Give the CAN frames a chance to go out.
    delay(5);
  }
}

void SetupPwmFtm(BigFTM *ftm) {
  ftm->MODE = FTM_MODE_WPDIS;
  ftm->MODE = FTM_MODE_WPDIS | FTM_MODE_FTMEN;
  ftm->SC = FTM_SC_CLKS(0) /* Disable counting for now */;

  // Can't change MOD according to the reference manual ("The Dual Edge Capture
  // mode must be used with ...  the FTM counter in Free running counter.").
  ftm->MOD = 0xFFFF;

  // Capturing rising edge.
  ftm->C0SC = FTM_CSC_MSA | FTM_CSC_ELSA;
  // Capturing falling edge.
  ftm->C1SC = FTM_CSC_CHIE | FTM_CSC_MSA | FTM_CSC_ELSB;

  // Capturing rising edge.
  ftm->C2SC = FTM_CSC_MSA | FTM_CSC_ELSA;
  // Capturing falling edge.
  ftm->C3SC = FTM_CSC_CHIE | FTM_CSC_MSA | FTM_CSC_ELSB;

  // Capturing rising edge.
  ftm->C4SC = FTM_CSC_MSA | FTM_CSC_ELSA;
  // Capturing falling edge.
  ftm->C5SC = FTM_CSC_CHIE | FTM_CSC_MSA | FTM_CSC_ELSB;

  // Capturing rising edge.
  ftm->C6SC = FTM_CSC_MSA | FTM_CSC_ELSA;
  // Capturing falling edge.
  ftm->C7SC = FTM_CSC_CHIE | FTM_CSC_MSA | FTM_CSC_ELSB;

  (void)ftm->STATUS;
  ftm->STATUS = 0x00;

  ftm->COMBINE = FTM_COMBINE_DECAP3 | FTM_COMBINE_DECAPEN3 |
                 FTM_COMBINE_DECAP2 | FTM_COMBINE_DECAPEN2 |
                 FTM_COMBINE_DECAP1 | FTM_COMBINE_DECAPEN1 |
                 FTM_COMBINE_DECAP0 | FTM_COMBINE_DECAPEN0;

  // 34.95ms max period before it starts wrapping and being weird.
  ftm->SC = FTM_SC_CLKS(1) /* Use the system clock */ |
            FTM_SC_PS(4) /* Prescaler=32 */;

  ftm->MODE &= ~FTM_MODE_WPDIS;
}

extern "C" void ftm0_isr() {
  while (true) {
    const uint32_t status = FTM0->STATUS;
    if (status == 0) {
      return;
    }

    if (status & (1 << 1)) {
      const uint32_t start = FTM0->C0V;
      const uint32_t end = FTM0->C1V;
      pwm_input_widths[0] = (end - start) & 0xFFFF;
      pwm_input_times[0] = millis();
    }
    if (status & (1 << 7)) {
      const uint32_t start = FTM0->C6V;
      const uint32_t end = FTM0->C7V;
      pwm_input_widths[1] = (end - start) & 0xFFFF;
      pwm_input_times[1] = millis();
    }
    if (status & (1 << 5)) {
      const uint32_t start = FTM0->C4V;
      const uint32_t end = FTM0->C5V;
      pwm_input_widths[2] = (end - start) & 0xFFFF;
      pwm_input_times[2] = millis();
    }
    if (status & (1 << 3)) {
      const uint32_t start = FTM0->C2V;
      const uint32_t end = FTM0->C3V;
      pwm_input_widths[4] = (end - start) & 0xFFFF;
      pwm_input_times[4] = millis();
    }

    FTM0->STATUS = 0;
  }
}

extern "C" void ftm3_isr() {
  while (true) {
    const uint32_t status = FTM3->STATUS;
    if (status == 0) {
      return;
    }

    if (status & (1 << 3)) {
      const uint32_t start = FTM3->C2V;
      const uint32_t end = FTM3->C3V;
      pwm_input_widths[3] = (end - start) & 0xFFFF;
      pwm_input_times[3] = millis();
    }

    FTM3->STATUS = 0;
  }
}

float ConvertEncoderChannel(uint16_t reading) {
  // Theoretical values based on the datasheet are 931 and 2917.
  // With these values, the magnitude ranges from 0.99-1.03, which works fine
  // (the encoder's output appears to get less accurate in one quadrant for some
  // reason, hence the variation).
  static constexpr uint16_t kMin = 802, kMax = 3088;
  if (reading < kMin) {
    reading = kMin;
  } else if (reading > kMax) {
    reading = kMax;
  }
  return (static_cast<float>(2 * (reading - kMin)) /
          static_cast<float>(kMax - kMin)) -
         1.0f;
}

struct EncoderReading {
  EncoderReading(const salsa::SimpleAdcReadings &adc_readings) {
    const float sin = ConvertEncoderChannel(adc_readings.sin);
    const float cos = ConvertEncoderChannel(adc_readings.cos);

    const float magnitude = ::std::sqrt(sin * sin + cos * cos);
    const float magnitude_error = ::std::abs(magnitude - 1.0f);
    valid = magnitude_error < 0.15f;

    angle = ::std::atan2(sin, cos);
  }

  // Angle in radians, in [-pi, pi].
  float angle;

  bool valid;
};

extern "C" void pit3_isr() {
  PIT_TFLG3 = 1;

  salsa::SimpleAdcReadings adc_readings;
  {
    DisableInterrupts disable_interrupts;
    adc_readings = salsa::AdcReadSimple(disable_interrupts);
  }

  EncoderReading encoder(adc_readings);

  printf("TODO(Austin): 1kHz loop %d %d %d %d %d ADC %" PRIu16 " %" PRIu16
         " enc %d/1000 %s from %d\n",
         (int)(convert_input_width(0) * 1000),
         (int)(convert_input_width(1) * 1000),
         (int)(convert_input_width(2) * 1000),
         (int)(convert_input_width(3) * 1000),
         (int)(convert_input_width(4) * 1000), adc_readings.sin,
         adc_readings.cos, (int)(encoder.angle * 1000),
         encoder.valid ? "T" : "f",
         (int)(::std::sqrt(ConvertEncoderChannel(adc_readings.sin) *
                               ConvertEncoderChannel(adc_readings.sin) +
                           ConvertEncoderChannel(adc_readings.cos) *
                               ConvertEncoderChannel(adc_readings.cos)) *
               1000));
}

}  // namespace

extern "C" {

void *__stack_chk_guard = (void *)0x67111971;

int _write(int /*file*/, char *ptr, int len) {
  teensy::AcmTty *const tty = global_stdout.load(::std::memory_order_acquire);
  if (tty != nullptr) {
    return tty->Write(ptr, len);
  }
  return 0;
}

void __stack_chk_fail(void);

}  // extern "C"

extern "C" int main(void) {
  // for background about this startup delay, please see these conversations
  // https://forum.pjrc.com/threads/36606-startup-time-(400ms)?p=113980&viewfull=1#post113980
  // https://forum.pjrc.com/threads/31290-Teensey-3-2-Teensey-Loader-1-24-Issues?p=87273&viewfull=1#post87273
  delay(400);

  // Set all interrupts to the second-lowest priority to start with.
  for (int i = 0; i < NVIC_NUM_INTERRUPTS; i++) NVIC_SET_SANE_PRIORITY(i, 0xD);

  // Now set priorities for all the ones we care about. They only have meaning
  // relative to each other, which means centralizing them here makes it a lot
  // more manageable.
  NVIC_SET_SANE_PRIORITY(IRQ_USBOTG, 0x7);
  NVIC_SET_SANE_PRIORITY(IRQ_FTM0, 0xa);
  NVIC_SET_SANE_PRIORITY(IRQ_FTM3, 0xa);
  NVIC_SET_SANE_PRIORITY(IRQ_PIT_CH3, 0x5);

  // Builtin LED.
  PERIPHERAL_BITBAND(GPIOC_PDOR, 5) = 1;
  PORTC_PCR5 = PORT_PCR_DSE | PORT_PCR_SRE | PORT_PCR_MUX(1);
  PERIPHERAL_BITBAND(GPIOC_PDDR, 5) = 1;

  // Set up the CAN pins.
  PORTA_PCR12 = PORT_PCR_DSE | PORT_PCR_MUX(2);
  PORTA_PCR13 = PORT_PCR_DSE | PORT_PCR_MUX(2);

  // PWM_IN0
  // FTM0_CH0
  PORTC_PCR1 = PORT_PCR_MUX(4);

  // PWM_IN1
  // FTM0_CH6
  PORTD_PCR6 = PORT_PCR_MUX(4);

  // PWM_IN2
  // FTM0_CH4
  PORTD_PCR4 = PORT_PCR_MUX(4);

  // PWM_IN3
  // FTM3_CH2
  PORTD_PCR2 = PORT_PCR_MUX(4);

  // PWM_IN4
  // FTM0_CH2
  PORTC_PCR3 = PORT_PCR_MUX(4);

  delay(100);

  teensy::UsbDevice usb_device(0, 0x16c0, 0x0492);
  usb_device.SetManufacturer("Seems Reasonable LLC");
  usb_device.SetProduct("Simple Receiver Board");

  teensy::AcmTty tty0(&usb_device);
  global_stdout.store(&tty0, ::std::memory_order_release);
  usb_device.Initialize();

  SIM_SCGC6 |= SIM_SCGC6_PIT;
  // Workaround for errata e7914.
  (void)PIT_MCR;
  PIT_MCR = 0;
  PIT_LDVAL3 = (BUS_CLOCK_FREQUENCY / 1000) - 1;
  PIT_TCTRL3 = PIT_TCTRL_TIE | PIT_TCTRL_TEN;

  can_init(0, 1);
  salsa::AdcInitSimple();
  SetupPwmFtm(FTM0);
  SetupPwmFtm(FTM3);

  // Leave the LEDs on for a bit longer.
  delay(300);
  printf("Done starting up\n");

  // Done starting up, now turn the LED off.
  PERIPHERAL_BITBAND(GPIOC_PDOR, 5) = 0;

  NVIC_ENABLE_IRQ(IRQ_FTM0);
  NVIC_ENABLE_IRQ(IRQ_FTM3);
  NVIC_ENABLE_IRQ(IRQ_PIT_CH3);

  DoReceiverTest2();

  return 0;
}

void __stack_chk_fail(void) {
  while (true) {
    GPIOC_PSOR = (1 << 5);
    printf("Stack corruption detected\n");
    delay(1000);
    GPIOC_PCOR = (1 << 5);
    delay(1000);
  }
}

}  // namespace motors
}  // namespace frc971