pimoroni-pico/drivers/st7789/st7789.cpp

#include "st7789.hpp"

#include <cstdlib>
#include <math.h>

namespace pimoroni {
  uint8_t madctl;
  uint16_t caset[2] = {0, 0};
  uint16_t raset[2] = {0, 0};

  enum MADCTL : uint8_t {
    ROW_ORDER   = 0b10000000,
    COL_ORDER   = 0b01000000,
    SWAP_XY     = 0b00100000,  // AKA "MV"
    SCAN_ORDER  = 0b00010000,
    RGB         = 0b00001000,
    HORIZ_ORDER = 0b00000100
  };

  enum reg {
    SWRESET   = 0x01,
    TEOFF     = 0x34,
    TEON      = 0x35,
    MADCTL    = 0x36,
    COLMOD    = 0x3A,
    GCTRL     = 0xB7,
    VCOMS     = 0xBB,
    LCMCTRL   = 0xC0,
    VDVVRHEN  = 0xC2,
    VRHS      = 0xC3,
    VDVS      = 0xC4,
    FRCTRL2   = 0xC6,
    PWCTRL1   = 0xD0,
    PORCTRL   = 0xB2,
    GMCTRP1   = 0xE0,
    GMCTRN1   = 0xE1,
    INVOFF    = 0x20,
    SLPOUT    = 0x11,
    DISPON    = 0x29,
    GAMSET    = 0x26,
    DISPOFF   = 0x28,
    RAMWR     = 0x2C,
    INVON     = 0x21,
    CASET     = 0x2A,
    RASET     = 0x2B,
    PWMFRSEL  = 0xCC
  };

  void ST7789::init() {
    command(reg::SWRESET);

    sleep_ms(150);

    // Common init
    command(reg::TEON);  // enable frame sync signal if used
    command(reg::COLMOD,    1, "\x05");  // 16 bits per pixel

    command(reg::PORCTRL, 5, "\x0c\x0c\x00\x33\x33");
    command(reg::LCMCTRL, 1, "\x2c");
    command(reg::VDVVRHEN, 1, "\x01");
    command(reg::VRHS, 1, "\x12");
    command(reg::VDVS, 1, "\x20");
    command(reg::PWCTRL1, 2, "\xa4\xa1");
    command(reg::FRCTRL2, 1, "\x0f");

    if(width == 240 && height == 240) {
      command(reg::GCTRL, 1, "\x14");
      command(reg::VCOMS, 1, "\x37");
      command(reg::GMCTRP1, 14, "\xD0\x04\x0D\x11\x13\x2B\x3F\x54\x4C\x18\x0D\x0B\x1F\x23");
      command(reg::GMCTRN1, 14, "\xD0\x04\x0C\x11\x13\x2C\x3F\x44\x51\x2F\x1F\x1F\x20\x23");
    }

    if((width == 320 && height == 240)
    || (width == 240 && height == 320)) {
      command(reg::GCTRL, 1, "\x35");
      command(reg::VCOMS, 1, "\x1f");
      command(0xd6, 1, "\xa1"); // ???
      command(reg::GMCTRP1, 14, "\xD0\x08\x11\x08\x0C\x15\x39\x33\x50\x36\x13\x14\x29\x2D");
      command(reg::GMCTRN1, 14, "\xD0\x08\x10\x08\x06\x06\x39\x44\x51\x0B\x16\x14\x2F\x31");
    }

    command(reg::INVON);   // set inversion mode
    command(reg::SLPOUT);  // leave sleep mode
    command(reg::DISPON);  // turn display on

    sleep_ms(100);

    configure_display(false);

    if(bl != PIN_UNUSED) {
      update(); // Send the new buffer to the display to clear any previous content
      sleep_ms(50); // Wait for the update to apply
      set_backlight(255); // Turn backlight on now surprises have passed
    }
  }

  void ST7789::configure_display(bool rotate180) {
    // 240x240 Square and Round LCD Breakouts
    // TODO: How can we support 90 degree rotations here?
    if(width == 240 && height == 240) {
      caset[0] = 0;
      caset[1] = 239;
      if(round) {
        raset[0] = 40;
        raset[1] = 279;
      } else {
        raset[0] = rotate180 ? 80 : 0;
        raset[1] = rotate180 ? 329 : 239;
      }
      madctl = rotate180 ? (MADCTL::COL_ORDER | MADCTL::ROW_ORDER) : 0;
      madctl |= MADCTL::HORIZ_ORDER;
    }

    // Pico Display
    if(width == 240 && height == 135) {
      caset[0] = 40;   // 240 cols
      caset[1] = 279;
      raset[0] = 53;   // 135 rows
      raset[1] = 187;
      madctl = rotate180 ? MADCTL::ROW_ORDER : MADCTL::COL_ORDER;
      madctl |= MADCTL::SWAP_XY | MADCTL::SCAN_ORDER;
    }

    // Pico Display at 90 degree rotation
    if(width == 135 && height == 240) {
      caset[0] = 52;   // 135 cols
      caset[1] = 186;
      raset[0] = 40;   // 240 rows
      raset[1] = 279;
      madctl = rotate180 ? (MADCTL::COL_ORDER | MADCTL::ROW_ORDER) : 0;
    }

    // Pico Display 2.0
    if(width == 320 && height == 240) {
      caset[0] = 0;
      caset[1] = 319;
      raset[0] = 0;
      raset[1] = 239;
      madctl = rotate180 ? MADCTL::ROW_ORDER : MADCTL::COL_ORDER;
      madctl |= MADCTL::SWAP_XY | MADCTL::SCAN_ORDER;
    }

    // Pico Display 2.0 at 90 degree rotation
    if(width == 240 && height == 320) {
      caset[0] = 0;
      caset[1] = 239;
      raset[0] = 0;
      raset[1] = 319;
      madctl = rotate180 ? (MADCTL::COL_ORDER | MADCTL::ROW_ORDER) : 0;
    }

    // Byte swap the 16bit rows/cols values
    caset[0] = __builtin_bswap16(caset[0]);
    caset[1] = __builtin_bswap16(caset[1]);
    raset[0] = __builtin_bswap16(raset[0]);
    raset[1] = __builtin_bswap16(raset[1]);

    command(reg::CASET,  4, (char *)caset);
    command(reg::RASET,  4, (char *)raset);
    command(reg::MADCTL, 1, (char *)&madctl);
  }

  spi_inst_t* ST7789::get_spi() const {
    return spi;
  }

  uint ST7789::get_cs() const {
    return cs;
  }

  uint ST7789::get_dc() const {
    return dc;
  }

  uint ST7789::get_sck() const {
    return sck;
  }

  uint ST7789::get_mosi() const {
    return mosi;
  }

  uint ST7789::get_bl() const {
    return bl;
  }

  void ST7789::command(uint8_t command, size_t len, const char *data) {
    gpio_put(cs, 0);

    gpio_put(dc, 0); // command mode
    spi_write_blocking(spi, &command, 1);

    if(data) {
      gpio_put(dc, 1); // data mode
      spi_write_blocking(spi, (const uint8_t*)data, len);
    }

    gpio_put(cs, 1);
  }

  void ST7789::update() {
    command(reg::RAMWR, width * height * sizeof(uint16_t), (const char*)frame_buffer);
  }

  void ST7789::set_backlight(uint8_t brightness) {
    // gamma correct the provided 0-255 brightness value onto a
    // 0-65535 range for the pwm counter
    float gamma = 2.8;
    uint16_t value = (uint16_t)(pow((float)(brightness) / 255.0f, gamma) * 65535.0f + 0.5f);
    pwm_set_gpio_level(bl, value);
  }

  void ST7789::flip(){
    configure_display(true);
  }
}