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_BGR     = 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::common_init() {
    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
    }

    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) {
      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(rotation);

    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::cleanup() {
    if(spi) return; // SPI mode needs no tear down
    if(dma_channel_is_claimed(parallel_dma)) {
      dma_channel_abort(parallel_dma);
      dma_channel_unclaim(parallel_dma);
    }

    if(pio_sm_is_claimed(parallel_pio, parallel_sm)) {
      pio_sm_set_enabled(parallel_pio, parallel_sm, false);
      pio_sm_drain_tx_fifo(parallel_pio, parallel_sm);
      pio_sm_unclaim(parallel_pio, parallel_sm);
    }
  }

  void ST7789::configure_display(Rotation rotate) {

    bool rotate180 = rotate == ROTATE_180 || rotate == ROTATE_90;

    if(rotate == ROTATE_90 || rotate == ROTATE_270) {
      std::swap(width, height);
    }

    // 240x240 Square and Round LCD Breakouts
    if(width == 240 && height == 240) {
      int row_offset = round ? 40 : 80;
      int col_offset = 0;
    
      switch(rotate) {
        case ROTATE_90:
          if (!round) row_offset = 0;
          caset[0] = row_offset;
          caset[1] = width + row_offset - 1;
          raset[0] = col_offset;
          raset[1] = width + col_offset - 1;

          madctl = MADCTL::HORIZ_ORDER | MADCTL::COL_ORDER | MADCTL::SWAP_XY;
          break;
        case ROTATE_180:
          caset[0] = col_offset;
          caset[1] = width + col_offset - 1;
          raset[0] = row_offset;
          raset[1] = width + row_offset - 1;

          madctl = MADCTL::HORIZ_ORDER | MADCTL::COL_ORDER | MADCTL::ROW_ORDER;
          break;
        case ROTATE_270:
          caset[0] = row_offset;
          caset[1] = width + row_offset - 1;
          raset[0] = col_offset;
          raset[1] = width + col_offset - 1;

          madctl = MADCTL::ROW_ORDER | MADCTL::SWAP_XY;
          break;
        default: // ROTATE_0 (and for any smart-alec who tries to rotate 45 degrees or something...)
          if (!round) row_offset = 0;
          caset[0] = col_offset;
          caset[1] = width + col_offset - 1;
          raset[0] = row_offset;
          raset[1] = width + row_offset - 1;

          madctl = MADCTL::HORIZ_ORDER;
          break;
      }
    }

    // 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);
  }

  void ST7789::write_blocking_parallel_dma(const uint8_t *src, size_t len) {
    while (dma_channel_is_busy(parallel_dma))
      ;
    dma_channel_set_trans_count(parallel_dma, len, false);
    dma_channel_set_read_addr(parallel_dma, src, true);
  }

  void ST7789::write_blocking_parallel(const uint8_t *src, size_t len) {
    const uint8_t *p = src;
    while(len--) {
      // Does not byte align correctly
      //pio_sm_put_blocking(parallel_pio, parallel_sm, *p);
      while (pio_sm_is_tx_fifo_full(parallel_pio, parallel_sm))
        ;
      *(volatile uint8_t*)&parallel_pio->txf[parallel_sm] = *p;
      p++;
    }

    uint32_t sm_stall_mask = 1u << (parallel_sm + PIO_FDEBUG_TXSTALL_LSB);
    parallel_pio->fdebug = sm_stall_mask;
      while (!(parallel_pio->fdebug & sm_stall_mask))
          ;
    /*uint32_t mask = 0xff << d0;
    while(len--) {
      gpio_put(wr_sck, false);     
      uint8_t v = *src++;
      gpio_put_masked(mask, v << d0);
      //asm("nop;");
      gpio_put(wr_sck, true);
      asm("nop;");
    }*/
  }

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

    gpio_put(cs, 0);
    
    if(spi) {
      spi_write_blocking(spi, &command, 1);
    } else {
      write_blocking_parallel(&command, 1);
    }

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

    gpio_put(cs, 1);
  }
  
  void ST7789::update(PicoGraphics *graphics) {
    uint8_t cmd = reg::RAMWR;

    if(graphics->pen_type == PicoGraphics::PEN_RGB565) { // Display buffer is screen native
      command(cmd, width * height * sizeof(uint16_t), (const char*)graphics->frame_buffer);
    } else if(spi) { // SPI Bus
      gpio_put(dc, 0); // command mode
      gpio_put(cs, 0);
      spi_write_blocking(spi, &cmd, 1);
      gpio_put(dc, 1); // data mode

      graphics->scanline_convert(PicoGraphics::PEN_RGB565, [this](void *data, size_t length) {
        spi_write_blocking(spi, (const uint8_t*)data, length);
      });
  
      gpio_put(cs, 1);
    } else { // Parallel Bus
      gpio_put(dc, 0); // command mode
      gpio_put(cs, 0);
      write_blocking_parallel(&cmd, 1);
      gpio_put(dc, 1); // data mode

      int scanline = 0;

      graphics->scanline_convert(PicoGraphics::PEN_RGB565, [this, scanline](void *data, size_t length) mutable {
        write_blocking_parallel_dma((const uint8_t*)data, length);

        // Stall on the last scanline since "data" goes out of scope and is lost
        scanline++;
        if(scanline == height) {
            while (dma_channel_is_busy(parallel_dma))
            ;
        }
      });

      gpio_put(cs, 1);
    }
  }

  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);
  }
}