ST7701: Experimental driver stub.

drivers/CMakeLists.txt

@@ -6,6 +6,7 @@ add_subdirectory(ltp305)
 add_subdirectory(ltr559)
 add_subdirectory(pmw3901)
 add_subdirectory(sgp30)
+add_subdirectory(st7701)
 add_subdirectory(st7735)
 add_subdirectory(st7789)
 add_subdirectory(msa301)

drivers/st7701/CMakeLists.txt

@@ -0,0 +1 @@
+include(${CMAKE_CURRENT_LIST_DIR}/st7701.cmake)

drivers/st7701/README.md

@@ -0,0 +1,56 @@
+# ST7701 Display Driver for Pimoroni LCDs <!-- omit in toc -->
+
+The ST7701 driver supports both Parallel and Serial (SPI) ST7701 displays and is intended for use with:
+
+* Redacted
+* Wouldn't you like to know
+* Super Sekret
+
+## Setup
+
+Construct an instance of the ST7701 driver with either Parallel or SPI pins.
+
+Parallel:
+
+```c++
+ST7701 st7701(WIDTH, HEIGHT, ROTATE_0, {
+    Tufty2040::LCD_CS,   // Chip-Select
+    Tufty2040::LCD_DC,   // Data-Command
+    Tufty2040::LCD_WR,   // Write
+    Tufty2040::LCD_RD,   // Read
+    Tufty2040::LCD_D0,   // Data 0 (start of a bank of 8 pins)
+    Tufty2040::BACKLIGHT // Backlight
+});
+```
+
+SPI:
+
+```c++
+ST7701 st7701(WIDTH, HEIGHT, ROTATE_0, false, {
+    PIMORONI_SPI_DEFAULT_INSTANCE, // SPI instance
+    SPI_BG_FRONT_CS,               // Chip-select
+    SPI_DEFAULT_SCK,               // SPI Clock
+    SPI_DEFAULT_MOSI,              // SPI Out
+    PIN_UNUSED,                    // SPI In
+    SPI_DEFAULT_DC,                // SPI Data/Command
+    PIN_UNUSED                     // Backlight
+});
+```
+
+## Reference
+
+### Update
+
+ST7701's `update` accepts an instance of `PicoGraphics` in any colour mode:
+
+```c++
+st7701.update(&graphics);
+```
+
+### Set Backlight
+
+If a backlight pin has been configured, you can set the backlight from 0 to 255:
+
+```c++
+st7701.set_backlight(128)
+```

drivers/st7701/st7701.cmake

@@ -0,0 +1,14 @@
+set(DRIVER_NAME st7701)
+add_library(${DRIVER_NAME} INTERFACE)
+
+target_sources(${DRIVER_NAME} INTERFACE
+  ${CMAKE_CURRENT_LIST_DIR}/${DRIVER_NAME}.cpp)
+
+pico_generate_pio_header(${DRIVER_NAME} ${CMAKE_CURRENT_LIST_DIR}/st7701_parallel.pio)
+
+target_include_directories(${DRIVER_NAME} INTERFACE ${CMAKE_CURRENT_LIST_DIR})
+
+target_include_directories(st7701 INTERFACE ${CMAKE_CURRENT_LIST_DIR})
+
+# Pull in pico libraries that we need
+target_link_libraries(${DRIVER_NAME} INTERFACE pico_stdlib pimoroni_bus hardware_spi hardware_pwm hardware_pio hardware_dma pico_graphics)

drivers/st7701/st7701.cpp

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+#include "st7701.hpp"
+
+#include <cstdlib>
+#include <math.h>
+
+namespace pimoroni {
+  uint8_t madctl;
+
+  enum dcx {
+    CMD = 0x00,
+    DATA = 0x01
+  };
+
+  enum reg {
+    SWRESET = 0x01, // Software Reset
+    SLPOUT = 0x11,  // Sleep Out
+    PTLON = 0x12,   // Partial Display Mode On
+    NORON = 0x13,   // Normal Display Mode On
+    INVOFF = 0x20,  // Display Inversion Off
+    INVON = 0x21,   // Display Inversion On
+    ALLPOFF = 0x22, // All Pixels Off
+    ALLPON = 0x23,  // All Pixels On
+    GAMSET = 0x26,  // Gamma Set
+    DISPOFF = 0x28, // Display Off
+    DISPON = 0x29,  // Display On
+    TEOFF = 0x34,   // Tearing Effect Line Off (kinda vsync)
+    TEON = 0x35,    // Tearing Effect Line On (kinda vsync)
+    MADCTL = 0x36,  // Display data access control
+    IDMOFF = 0x38,  // Idle Mode Off
+    IDMON = 0x39,   // Idle Mode On
+    COLMOD = 0x3A,  // Interface Pixel Format
+    GSL = 0x45,     // Get Scan Line
+    // Command2_BK0
+    PVGAMCTRL = 0xB0,  // Positive Voltage Gamma Control
+    NVGAMCTRL = 0xB1,  // Negative Voltage Gamma Control
+    DGMEN = 0xB8,   // Digital Gamma Enable
+    DGMLUTR = 0xB9, // Digital Gamma LUT for Red
+    DGMLUTB = 0xBA, // Digital Gamma Lut for Blue
+    LNESET = 0xC0,  // Display Line Setting
+    PORCTRL = 0xC1, // Porch Control
+    INVSET = 0xC2,  // Inversion Selection & Frame Rate Control
+    RGBCTRL = 0xC3, // RGB Control
+    PARCTRL = 0xC5, // Partial Mode Control
+    SDIR = 0xC7,    // X-direction Control
+    PDOSET = 0xC8,  // Pseudo-Dot Inversion Diving Settign
+    COLCTRL = 0xCD, // Colour Control
+    SRECTRL = 0xE0, // Sunlight Readable Enhancement
+    NRCTRL = 0xE1,  // Noise Reduce Control
+    SECTRL = 0xE2,  // Sharpness Control
+    CCCTRL = 0xE3,  // Color Calibration Control
+    SKCTRL = 0xE4,  // Skin Tone Preservation Control
+    // Command2_BK1
+    VHRS = 0xB0,    // Vop amplitude
+    VCOMS = 0xB1,   // VCOM amplitude
+    VGHSS = 0xB2,   // VGH voltage
+    TESTCMD = 0xB3, // TEST command
+    VGLS = 0xB5,    // VGL voltage
+    VRHDV = 0xB6,   // VRH_DV voltage
+    PWCTRL1 = 0xB7, // Power Control 1
+    PWCTRL2 = 0xB8, // Power Control 2
+    PCLKS1 = 0xBA,  // Power pumping clock selection 1
+    PCLKS2 = 0xBC,  // Power pumping clock selection 2
+    PDR1 = 0xC1,    // Source pre_drive timing set 1
+    PDR2 = 0xC2,    // Source pre_drive timing set 2
+    // Command2_BK3
+    NVMEN = 0xC8,    // NVM enable
+    NVMSET = 0xCA,   // NVM manual control
+    PROMACT = 0xCC,  // NVM program active
+    // Other
+    CND2BKxSEL = 0xFF,
+  };
+
+  void ST7701::common_init() {
+    // if a backlight pin is provided then set it up for
+    // pwm control
+    if(lcd_bl != PIN_UNUSED) {
+      pwm_config cfg = pwm_get_default_config();
+      pwm_set_wrap(pwm_gpio_to_slice_num(lcd_bl), 65535);
+      pwm_init(pwm_gpio_to_slice_num(lcd_bl), &cfg, true);
+      gpio_set_function(lcd_bl, GPIO_FUNC_PWM);
+      set_backlight(0); // Turn backlight off initially to avoid nasty surprises
+    }
+
+    command(reg::SWRESET);
+
+    sleep_ms(150);
+
+    // Commmand 2 BK0 - kinda a page select
+    command(reg::CND2BKxSEL, 5, "\x77\x01\x00\x00\x10");
+
+    if(width == 480 && height == 480) {
+      // TODO: Figure out what's actually display specific
+      command(reg::MADCTL, 1, "\x00");  // Normal scan direction and RGB pixels
+      command(reg::LNESET, 2, "\x3b\x00");   // (59 + 1) * 8 = 480 lines
+      command(reg::PORCTRL, 2, "\x0d\x02");  // 13 VBP, 2 VFP
+      command(reg::INVSET, 2, "\x32\x05");
+      command(reg::COLCTRL, 1, "\x08");      // LED polarity reversed
+      command(reg::PVGAMCTRL, 16, "\x00\x11\x18\x0e\x11\x06\x07\x08\x07\x22\x04\x12\x0f\xaa\x31\x18");
+      command(reg::NVGAMCTRL, 16, "\x00\x11\x19\x0e\x12\x07\x08\x08\x08\x22\x04\x11\x11\xa9\x32\x18");
+    }
+
+    // Command 2 BK1 - Voltages and power and stuff
+    command(reg::CND2BKxSEL, 5, "\x77\x01\x00\x00\x11");
+    command(reg::VHRS, 1, "\x60");    // 4.7375v
+    command(reg::VCOMS, 1, "\x32");   // 0.725v
+    command(reg::VGHSS, 1, "\x07");   // 15v
+    command(reg::TESTCMD, 1, "\x80"); // y tho?
+    command(reg::VGLS, 1, "\x49");    // -10.17v
+    command(reg::PWCTRL1, 1, "\x85"); // Middle/Min/Min bias
+    command(reg::PWCTRL2, 1, "\x21"); // 6.6 / -4.6
+    command(reg::PDR1, 1, "\x78");    // 1.6uS
+    command(reg::PDR2, 1, "\x78");    // 6.4uS
+
+    // Begin Forbidden Knowledge
+    // This sequence is probably specific to TL040WVS03CT15-H1263A.
+    // It is not documented in the ST7701s datasheet.
+    // TODO: 👇 W H A T ! ? 👇
+    command(0xE0, 3, "\x00\x1b\x02");
+    command(0xE1, 11, "\x08\xa0\x00\x00\x07\xa0\x00\x00\x00\x44\x44");
+    command(0xE2, 12, "\x11\x11\x44\x44\xed\xa0\x00\x00\xec\xa0\x00\x00");
+    command(0xE3, 4, "\x00\x00\x11\x11");
+    command(0xE4, 2, "\x44\x44");
+    command(0xE5, 16, "\x0a\xe9\xd8\xa0\x0c\xeb\xd8\xa0\x0e\xed\xd8\xa0\x10\xef\xd8\xa0");
+    command(0xE7, 2, "\x44\x44");
+    command(0xE8, 16, "\x09\xe8\xd8\xa0\x0b\xea\xd8\xa0\x0d\xec\xd8\xa0\x0f\xee\xd8\xa0");
+    command(0xEC, 2, "\x3c\x00");
+    command(0xED, 16, "\xab\x89\x76\x54\x02\xff\xff\xff\xff\xff\xff\x20\x45\x67\x98\xba");
+    command(0x36, 1, "\x00");
+    // End Forbidden Knowledge
+
+    // Command 2 BK3
+    command(reg::CND2BKxSEL, 5, "\x77\x01\x00\x00\x13");
+    //command(reg::COLMOD, 1, "\x77");  // 24 bits per pixel...
+    command(reg::COLMOD, 1, "\x66");    // 18 bits per pixel...
+    //command(reg::COLMOD, 1, "\x55");  // 16 bits per pixel...
+
+    command(reg::SLPOUT);
+    sleep_ms(120);
+    command(reg::DISPON);
+    sleep_ms(50);
+
+    // TODO: Support rotation
+    // configure_display(rotation);
+
+    if(lcd_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 ST7701::cleanup() {
+    if(dma_channel_is_claimed(st_dma)) {
+      dma_channel_abort(st_dma);
+      dma_channel_unclaim(st_dma);
+    }
+    if(spi) return; // SPI mode needs no further tear down
+
+    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 ST7701::configure_display(Rotation rotate) {
+
+    if(rotate == ROTATE_90 || rotate == ROTATE_270) {
+      std::swap(width, height);
+    }
+
+    // 480x480 Square Display
+    if(width == 480 && height == 480) {
+      madctl = 0;
+    }
+
+    command(reg::MADCTL, 1, (char *)&madctl);
+  }
+
+  void ST7701::write_blocking_dma(const uint8_t *src, size_t len) {
+    while (dma_channel_is_busy(st_dma))
+      ;
+    dma_channel_set_trans_count(st_dma, len, false);
+    dma_channel_set_read_addr(st_dma, src, true);
+  }
+
+  void ST7701::write_blocking_parallel(const uint8_t *src, size_t len) {
+    write_blocking_dma(src, len);
+    dma_channel_wait_for_finish_blocking(st_dma);
+
+    // This may cause a race between PIO and the
+    // subsequent chipselect deassert for the last pixel
+    while(!pio_sm_is_tx_fifo_empty(parallel_pio, parallel_sm))
+      ;
+  }
+
+  void ST7701::command(uint8_t command, size_t len, const char *data) {
+    static uint16_t _data[20] = {0};
+    gpio_put(spi_cs, 0);
+
+    // Add leading byte for 9th D/CX bit
+    uint8_t _command[2] = {dcx::CMD, command};
+    spi_write_blocking(spi, (const uint8_t*)_command, 2);
+
+    if(data) {
+      // Add leading bytes for 9th D/CX bits
+      // TODO: OOOF - I *think* this is how 9bit SPI is supposed to work!?
+      // We'd probably be better off with some dedicated PIO tomfoolery
+      for(auto i = 0u; i < len; i++) {
+        _data[i] = (dcx::DATA << 8) | data[i];
+      }
+      spi_write_blocking(spi, (const uint8_t*)_data, len);
+    }
+
+    gpio_put(spi_cs, 1);
+  }
+
+  void ST7701::update(PicoGraphics *graphics) {
+    //uint8_t cmd = reg::RAMWR;
+
+    // TODO: Where's my buffer at? Where's my buffer at?
+    // I left it out back in the PSRAM chip, y'all
+    // And now I cannot find it even though it's 60k tall
+
+    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 {
+      /*graphics->frame_convert(PicoGraphics::PEN_RGB565, [this](void *data, size_t length) {
+        if (length > 0) {
+          write_blocking_dma((const uint8_t*)data, length);
+        }
+        else {
+          dma_channel_wait_for_finish_blocking(st_dma);
+        }
+      });
+    }*/
+  }
+
+  void ST7701::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(lcd_bl, value);
+  }
+}