pimoroni-pico/drivers/st7789/st7789.hpp

#pragma once

#include "hardware/spi.h"
#include "hardware/gpio.h"
#include "hardware/pwm.h"
#include "common/pimoroni_common.hpp"
#include "common/pimoroni_bus.hpp"

#include <algorithm>


namespace pimoroni {

  class ST7789 {
    spi_inst_t *spi = PIMORONI_SPI_DEFAULT_INSTANCE;
  
  public:
    // screen properties
    uint16_t width;
    uint16_t height;
    Rotation rotation;
    bool round;

    //--------------------------------------------------
    // Variables
    //--------------------------------------------------
  private:

    // interface pins with our standard defaults where appropriate
    uint cs;
    uint dc;
    uint wr_sck;
    uint rd_sck = PIN_UNUSED;
    uint d0;
    uint bl;
    uint vsync  = PIN_UNUSED; // only available on some products

    // The ST7789 requires 16 ns between SPI rising edges.
    // 16 ns = 62,500,000 Hz
    static const uint32_t SPI_BAUD = 62'500'000;


  public:
  
    // frame buffer where pixel data is stored
    void *frame_buffer;

    // Parallel init
    ST7789(uint16_t width, uint16_t height, Rotation rotation, void *frame_buffer, ParallelPins pins) :
      spi(nullptr),
      width(width), height(height), rotation(rotation), round(false),
      cs(pins.cs), dc(pins.dc), wr_sck(pins.wr_sck), rd_sck(pins.rd_sck), d0(pins.d0), bl(pins.bl), frame_buffer(frame_buffer) {
  
      gpio_set_function(wr_sck, GPIO_FUNC_SIO);
      gpio_set_dir(wr_sck, GPIO_OUT);

      gpio_set_function(rd_sck,  GPIO_FUNC_SIO);
      gpio_set_dir(rd_sck, GPIO_OUT);

      for(auto i = 0u; i < 8; i++) {
        gpio_set_function(d0 + i, GPIO_FUNC_SIO);
        gpio_set_dir(d0 + i, GPIO_OUT);
      }
  
      gpio_put(rd_sck, 1);

      common_init();
    }

    // Serial init
    ST7789(uint16_t width, uint16_t height, Rotation rotation, bool round, void *frame_buffer, SPIPins pins) :
      spi(pins.spi),
      width(width), height(height), rotation(rotation), round(round),
      cs(pins.cs), dc(pins.dc), wr_sck(pins.sck), d0(pins.mosi), bl(pins.bl), frame_buffer(frame_buffer) {

      // configure spi interface and pins
      spi_init(spi, SPI_BAUD);

      gpio_set_function(wr_sck, GPIO_FUNC_SPI);
      gpio_set_function(d0, GPIO_FUNC_SPI);

      common_init();
    }

    void init();
    void command(uint8_t command, size_t len = 0, const char *data = NULL);
    void set_backlight(uint8_t brightness);

    void update();
    void update(uint16_t *palette);

  private:
    void configure_display(Rotation rotate);
    void write_blocking_parallel(const uint8_t *src, size_t len);
    void common_init() {
        if(!this->frame_buffer) {
          this->frame_buffer = new uint8_t[width * height];
        }

        gpio_set_function(dc, GPIO_FUNC_SIO);
        gpio_set_dir(dc, GPIO_OUT);

        gpio_set_function(cs, GPIO_FUNC_SIO);
        gpio_set_dir(cs, GPIO_OUT);

        // if a backlight pin is provided then set it up for
        // pwm control
        if(bl != PIN_UNUSED) {
          pwm_config cfg = pwm_get_default_config();
          pwm_set_wrap(pwm_gpio_to_slice_num(bl), 65535);
          pwm_init(pwm_gpio_to_slice_num(bl), &cfg, true);
          gpio_set_function(bl, GPIO_FUNC_PWM);
          set_backlight(0); // Turn backlight off initially to avoid nasty surprises
        }
    }
  };

}