pimoroni-pico/examples/pico_explorer_encoder/demo.cpp

#include <iomanip>
#include <sstream>
#include "pico_explorer.hpp"
#include "pico/stdlib.h"
#include "encoder.hpp"
#include "quadrature_out.pio.h"

using namespace pimoroni;


//--------------------------------------------------
// Constants
//--------------------------------------------------
static const uint8_t ENCODER_PIN_A            = 1;
static const uint8_t ENCODER_PIN_B            = 0;
static const uint8_t ENCODER_PIN_C            = Encoder::PIN_UNUSED;
static const uint8_t ENCODER_SWITCH_PIN       = 4;

static constexpr float COUNTS_PER_REVOLUTION  = 24;       // 24 is for rotary encoders. For motor magnetic encoders uses
                                                          // 12 times the gear ratio (e.g. 12 * 20 with a 20:1 ratio motor
static const bool COUNT_MICROSTEPS            = false;    // Set to true for motor magnetic encoders

static const uint16_t FREQ_DIVIDER            = 1;        // Increase this to deal with switch bounce. 250 Gives a 1ms debounce

static const int32_t TIME_BETWEEN_SAMPLES_US  = 100;      // Time between each sample, in microseconds
static const int32_t WINDOW_DURATION_US       = 1000000;  // The full time window that will be stored

static const int32_t READINGS_SIZE            = WINDOW_DURATION_US / TIME_BETWEEN_SAMPLES_US;
static const int32_t SCRATCH_SIZE             = READINGS_SIZE / 10;   // A smaller value, for temporarily storing readings during screen drawing

static const bool QUADRATURE_OUT_ENABLED      = true;
static constexpr float QUADRATURE_OUT_FREQ    = 800;      // The frequency the quadrature output will run at (note that counting microsteps will show 4x this value)
static const float QUADRATURE_OUT_1ST_PIN     = 6;        // Which first pin to output the quadrature signal to (e.g. pins 6 and 7)

static const uint64_t MAIN_LOOP_TIME_US       = 50000;    // How long there should be in microseconds between each screen refresh
static const uint16_t EDGE_ALIGN_ABOVE_ZOOM   = 4;        // The zoom level beyond which edge alignment will be enabled to ma



//--------------------------------------------------
// Enums
//--------------------------------------------------
enum DrawState {
  DRAW_LOW = 0,
  DRAW_HIGH,
  DRAW_TRANSITION,
};



//--------------------------------------------------
// Variables
//--------------------------------------------------

uint16_t buffer[PicoExplorer::WIDTH * PicoExplorer::HEIGHT];
PicoExplorer pico_explorer(buffer);

Encoder encoder(pio0, ENCODER_PIN_A, ENCODER_PIN_B, ENCODER_PIN_C, COUNTS_PER_REVOLUTION, COUNT_MICROSTEPS, FREQ_DIVIDER);

volatile bool encA_readings[READINGS_SIZE];
volatile bool encB_readings[READINGS_SIZE];
volatile bool encA_scratch[SCRATCH_SIZE];
volatile bool encB_scratch[SCRATCH_SIZE];
volatile uint32_t next_reading_index  = 0;
volatile uint32_t next_scratch_index  = 0;
volatile bool drawing_to_screen       = false;
uint16_t current_zoom_level           = 1;



////////////////////////////////////////////////////////////////////////////////////////////////////
// FUNCTIONS
////////////////////////////////////////////////////////////////////////////////////////////////////
uint32_t draw_plot(Point p1, Point p2, volatile bool (&readings)[READINGS_SIZE], uint32_t readingPos, bool edge_align) {
  uint32_t reading_window = READINGS_SIZE / current_zoom_level;
  uint32_t start_index_no_modulus = (readingPos + (READINGS_SIZE - reading_window));
  uint32_t start_index = start_index_no_modulus % READINGS_SIZE;
  int32_t screen_window = std::min(p2.x, (int32_t)PicoExplorer::WIDTH) - p1.x;

  bool last_reading = readings[start_index % READINGS_SIZE];

  uint32_t alignment_offset = 0;
  if(edge_align) {
    // Perform edge alignment by first seeing if there is a window of readings available (will be at anything other than x1 zoom)
    uint32_t align_window = (start_index_no_modulus - readingPos);

    // Then go backwards through that window
    for(uint32_t i = 1; i < align_window; i++) {
      uint32_t align_index = (start_index + (READINGS_SIZE - i)) % READINGS_SIZE;
      bool align_reading = readings[align_index];

      // Has a transition from high to low been detected?
      if(!align_reading && align_reading != last_reading) {
        // Set the new start index from which to draw from and break out of the search
        start_index = align_index;
        alignment_offset = i;
        break;
      }
      last_reading = align_reading;
    }

    last_reading = readings[start_index % READINGS_SIZE];
  }

  // Go through each X pixel within the screen window
  uint32_t reading_window_start = 0;
  for(int32_t x = 0; x < screen_window; x++) {
    uint32_t reading_window_end = ((x + 1) * reading_window) / screen_window;

    // Set the draw state to be whatever the last reading was
    DrawState draw_state = last_reading ? DRAW_HIGH : DRAW_LOW;

    // Go through the readings in this window to see if a transition from low to high or high to low occurs
    if(reading_window_end > reading_window_start) {
      for(uint32_t i = reading_window_start; i < reading_window_end; i++) {
        bool reading = readings[(i + start_index) % READINGS_SIZE];
        if(reading != last_reading) {
          draw_state = DRAW_TRANSITION;
          break;  // A transition occurred, so no need to continue checking readings
        }
        last_reading = reading;
      }
      last_reading = readings[((reading_window_end - 1) + start_index) % READINGS_SIZE];
    }
    reading_window_start = reading_window_end;

    // Draw a pixel in a high or low position, or a line between the two if a transition
    switch(draw_state) {
      case DRAW_TRANSITION:
        for(uint8_t y = p1.y; y < p2.y; y++)
          pico_explorer.pixel(Point(x + p1.x, y));
        break;
      case DRAW_HIGH:
        pico_explorer.pixel(Point(x + p1.x, p1.y));
        break;
      case DRAW_LOW:
        pico_explorer.pixel(Point(x + p1.x, p2.y - 1));
        break;
    }
  }

  // Return the alignment offset so subsequent encoder channel plots can share the alignment
  return alignment_offset;
}

////////////////////////////////////////////////////////////////////////////////////////////////////
bool repeating_timer_callback(struct repeating_timer *t) {
  if(drawing_to_screen && next_scratch_index < SCRATCH_SIZE) {
    encA_scratch[next_scratch_index] = encoder.get_state_a();
    encB_scratch[next_scratch_index] = encoder.get_state_b();
    next_scratch_index++;
  }
  else {
    encA_readings[next_reading_index] = encoder.get_state_a();
    encB_readings[next_reading_index] = encoder.get_state_b();

    next_reading_index++;
    if(next_reading_index >= READINGS_SIZE)
      next_reading_index = 0;
  }

  return true;
}


void setup() {
  stdio_init_all();

  gpio_init(PICO_DEFAULT_LED_PIN);
  gpio_set_dir(PICO_DEFAULT_LED_PIN, GPIO_OUT);

  if(ENCODER_SWITCH_PIN != Encoder::PIN_UNUSED) {
    gpio_init(ENCODER_SWITCH_PIN);
    gpio_set_dir(ENCODER_SWITCH_PIN, GPIO_IN);
    gpio_pull_down(ENCODER_SWITCH_PIN);
  }

  pico_explorer.init();
  pico_explorer.set_pen(0);
  pico_explorer.clear();
  pico_explorer.update();

  encoder.init();

  bool encA = encoder.get_state_a();
  bool encB = encoder.get_state_b();
  for(uint i = 0; i < READINGS_SIZE; i++) {
    encA_readings[i] = encA;
    encB_readings[i] = encB;
  }

  if(QUADRATURE_OUT_ENABLED) {
    // Set up the quadrature encoder output
    PIO pio = pio1;
    uint offset = pio_add_program(pio, &quadrature_out_program);
    uint sm = pio_claim_unused_sm(pio, true);
    quadrature_out_program_init(pio, sm, offset, QUADRATURE_OUT_1ST_PIN, QUADRATURE_OUT_FREQ);
  }
}



////////////////////////////////////////////////////////////////////////////////////////////////////
// MAIN
////////////////////////////////////////////////////////////////////////////////////////////////////
int main() {

  // Perform the main setup for the demo
  setup();

  // Begin the timer that will take readings of the coder at regular intervals
  struct repeating_timer timer;
  add_repeating_timer_us(-TIME_BETWEEN_SAMPLES_US, repeating_timer_callback, NULL, &timer);

  bool aPressedLatch = false;
  bool xPressedLatch = false;
  uint64_t last_time = time_us_64();

  while(true) {

    // Has enough time elapsed since we last refreshed the screen?
    uint64_t current_time = time_us_64();
    if(current_time > last_time + MAIN_LOOP_TIME_US) {
      last_time = current_time;

      gpio_put(PICO_DEFAULT_LED_PIN, true);    // Show the screen refresh has stated

      // If the user has wired up their encoder switch, and it is pressed, set the encoder count to zero
      if(ENCODER_SWITCH_PIN != Encoder::PIN_UNUSED && gpio_get(ENCODER_SWITCH_PIN)) {
        encoder.zero_count();
      }

      // Take a capture, or snapshot of the current encoder state
      Capture capture = encoder.perform_capture();

      // Spin Motor 1 either clockwise or counterclockwise depending on if B or Y are pressed
      if(pico_explorer.is_pressed(PicoExplorer::B) && !pico_explorer.is_pressed(PicoExplorer::Y)) {
        pico_explorer.set_motor(PicoExplorer::MOTOR1, PicoExplorer::FORWARD, 1.0f);
      }
      else if(pico_explorer.is_pressed(PicoExplorer::Y) && !pico_explorer.is_pressed(PicoExplorer::B)) {
        pico_explorer.set_motor(PicoExplorer::MOTOR1, PicoExplorer::REVERSE, 0.2f);
      }
      else {
        pico_explorer.set_motor(PicoExplorer::MOTOR1, PicoExplorer::STOP);
      }

      // If A has been pressed, zoom the view out to a min of x1
      if(pico_explorer.is_pressed(PicoExplorer::A)) {
        if(!aPressedLatch) {
          aPressedLatch = true;
          current_zoom_level = std::max(current_zoom_level / 2, 1);
        }
      }
      else {
        aPressedLatch = false;
      }

      // If X has been pressed, zoom the view in to the max of x512
      if(pico_explorer.is_pressed(PicoExplorer::X)) {
        if(!xPressedLatch) {
          xPressedLatch = true;
          current_zoom_level = std::min(current_zoom_level * 2, 512);
        }
      }
      else {
        xPressedLatch = false;
      }

      //--------------------------------------------------            
      // Draw the encoder readings to the screen as a signal plot

      pico_explorer.set_pen(0, 0, 0);
      pico_explorer.clear();

      drawing_to_screen = true;

      pico_explorer.set_pen(255, 255, 0);
      uint32_t localPos = next_reading_index;
      uint32_t alignment_offset = draw_plot(Point(0, 10), Point(PicoExplorer::WIDTH, 10 + 50), encA_readings, localPos, current_zoom_level > EDGE_ALIGN_ABOVE_ZOOM);

      pico_explorer.set_pen(0, 255, 255);
      draw_plot(Point(0, 80), Point(PicoExplorer::WIDTH, 80 + 50), encB_readings, (localPos + (READINGS_SIZE - alignment_offset)) % READINGS_SIZE, false);

      // Copy values that may have been stored in the scratch buffers, back into the main buffers
      for(uint16_t i = 0; i < next_scratch_index; i++) {
        encA_readings[next_reading_index] = encA_scratch[i];
        encB_readings[next_reading_index] = encB_scratch[i];

        next_reading_index++;
        if(next_reading_index >= READINGS_SIZE)
          next_reading_index = 0;
      }

      drawing_to_screen = false;
      next_scratch_index = 0;

      pico_explorer.set_pen(255, 255, 255);
      pico_explorer.character('A', Point(5, 10 + 15), 3);
      pico_explorer.character('B', Point(5, 80 + 15), 3);

      if(current_zoom_level < 10)
        pico_explorer.text("x" + std::to_string(current_zoom_level), Point(220, 62), 200, 2);
      else if(current_zoom_level < 100)
        pico_explorer.text("x" + std::to_string(current_zoom_level), Point(210, 62), 200, 2);
      else
        pico_explorer.text("x" + std::to_string(current_zoom_level), Point(200, 62), 200, 2);


      //--------------------------------------------------            
      // Write out the count, frequency and rpm of the encoder

      pico_explorer.set_pen(8, 8, 8);
      pico_explorer.rectangle(Rect(0, 140, PicoExplorer::WIDTH, PicoExplorer::HEIGHT - 140));

      pico_explorer.set_pen(64, 64, 64);
      pico_explorer.rectangle(Rect(0, 140, PicoExplorer::WIDTH, 2));

      {
        std::stringstream sstream;
        sstream << capture.get_count();
        pico_explorer.set_pen(255, 255, 255);   pico_explorer.text("Count:",      Point(10, 150),  200, 3);
        pico_explorer.set_pen(255, 128, 255);   pico_explorer.text(sstream.str(), Point(110, 150), 200, 3);
      }

      {
        std::stringstream sstream;
        sstream << std::fixed << std::setprecision(1) << capture.get_frequency() << "hz";
        pico_explorer.set_pen(255, 255, 255);   pico_explorer.text("Freq: ",      Point(10, 180), 220, 3);
        pico_explorer.set_pen(128, 255, 255);   pico_explorer.text(sstream.str(), Point(90, 180), 220, 3);
      }

      {
        std::stringstream sstream;
        sstream << std::fixed << std::setprecision(1) << capture.get_revolutions_per_minute();
        pico_explorer.set_pen(255, 255, 255);   pico_explorer.text("RPM: ",       Point(10, 210), 220, 3);
        pico_explorer.set_pen(255, 255, 128);   pico_explorer.text(sstream.str(), Point(80, 210), 220, 3);
      }

      pico_explorer.update();                 // Refresh the screen
      gpio_put(PICO_DEFAULT_LED_PIN, false);  // Show the screen refresh has ended
    }
  }
}