How to change SPI frequency of a predefined setting

[windorey]

Hello, I am using #define LGFX_M5STACK_CORE2 for my module, and it works, but I want to try 80mHz SPI mode to see if it will be faster. I don't know how to change the SPI frequency of a predefined device.

[tobozo]

assuming your lgfx object is named tft you can use this before tft.init():

  {
    auto _panel_instance = tft.getPanel();
    auto _bus_instance = (lgfx::Bus_SPI*)_panel_instance->getBus();
    auto _bus_cfg = _bus_instance->config();
    _bus_cfg.freq_write = 80000000;
    _bus_instance->config(_bus_cfg);
    _panel_instance->setBus( _bus_instance );
  }

[windorey]

Hello, thank you for your answer, but it doesn't work for me.
Refresh rate is still limited to 32,552083333, which for a 320x240 display running at 40mHz is correct.
Here is my full code:

/* #include <M5Core2.h> */

/* Include LVGL and create objects for the buffer */
#include <lvgl.h>
#include <lv_demo.h>
static const uint32_t screenWidth  = 320;
static const uint32_t screenHeight = 240;
static lv_disp_draw_buf_t draw_buf;
static lv_color_t buf[ screenWidth * 10 ];

/* Include LovyanGFX for V1 and Core2 */
#define LGFX_USE_V1
#define LGFX_M5STACK_CORE2
#include <LovyanGFX.hpp>
#include <LGFX_AUTODETECT.hpp>
static LGFX tft;

/* Flush the rendered pixels to the display */
void my_disp_flush( lv_disp_drv_t *disp, const lv_area_t *area, lv_color_t *color_p ) {
   uint32_t w = ( area->x2 - area->x1 + 1 );
   uint32_t h = ( area->y2 - area->y1 + 1 );

   tft.startWrite();
   tft.setAddrWindow( area->x1, area->y1, w, h );
   //tft.pushColors( ( uint16_t * )&color_p->full, w * h, true );
   tft.writePixels((lgfx::rgb565_t *)&color_p->full, w * h);
   tft.endWrite();

   lv_disp_flush_ready( disp );
}

/* Read the touch input */
void my_touchpad_read( lv_indev_drv_t * indev_driver, lv_indev_data_t * data ) {
   uint16_t touchX, touchY;
   bool touched = tft.getTouch( &touchX, &touchY);
   if( !touched )
   {
      data->state = LV_INDEV_STATE_REL;
   }
   else
   {
      data->state = LV_INDEV_STATE_PR;

      /*Set the coordinates*/
      data->point.x = touchX;
      data->point.y = touchY;
   }
}

/* Set up the LVGL display driver and touch indev driver */
void lv_setup() {
   lv_init();
   lv_disp_draw_buf_init( &draw_buf, buf, NULL, screenWidth * 10 );

   /*Initialize the display*/
   static lv_disp_drv_t disp_drv;
   lv_disp_drv_init(&disp_drv);

   /* Register the display driver */
   disp_drv.hor_res = screenWidth;
   disp_drv.ver_res = screenHeight;
   disp_drv.flush_cb = my_disp_flush;
   disp_drv.draw_buf = &draw_buf;
   lv_disp_drv_register(&disp_drv);

   /* Register the input driver */
   static lv_indev_drv_t indev_drv;
   lv_indev_drv_init(&indev_drv);
   indev_drv.type = LV_INDEV_TYPE_POINTER;
   indev_drv.read_cb = my_touchpad_read;
   lv_indev_drv_register(&indev_drv);
}

/* Timer handler task for LVGL */
static void LVGLTimerTask(void* param) {
  while(1)  {
    lv_timer_handler(); /* let the GUI do its work */
    /* vTaskDelay(5/portTICK_PERIOD_MS); */
  }
}

/* System tasks that never exit */
static void createSystemTasks(void) {
  xTaskCreatePinnedToCore(LVGLTimerTask, "LVGL Timer Handler", 10000, NULL, 5, NULL, ARDUINO_RUNNING_CORE); // Run the code to update the graphics with highest priority
}

void setup() {
    auto _panel_instance = tft.getPanel();
    auto _bus_instance = (lgfx::Bus_SPI*)_panel_instance->getBus();
    auto _bus_cfg = _bus_instance->config();
    _bus_cfg.freq_write = 80000000;
    _bus_instance->config(_bus_cfg);
    _panel_instance->setBus( _bus_instance );

  /* M5.begin(false, true, true, false); */

  tft.begin();        
  tft.setRotation(3);
  tft.setBrightness(255);
  tft.println("Loaded LovyanGFX");

  lv_setup();
  lv_demo_benchmark();
  createSystemTasks();
  if (!psramFound()) {
  log_e("Did not find psram");
  }
  else {
    log_v("Found psram");
  }
}

void loop() {
}

[tobozo]

sorry I forgot the panel/bus settings are eventually overwritten by autodetect 🤦

maybe try this after tft.begin(); ?

  {
    tft.releaseBus();
    auto _panel_instance = tft.getPanel();
    auto _bus_instance = (lgfx::Bus_SPI*)_panel_instance->getBus();
    auto _bus_cfg = _bus_instance->config();
    _bus_cfg.freq_write = 80000000;
    _bus_instance->config(_bus_cfg);
    _panel_instance->setBus( _bus_instance );
    // tft.setPanel(_panel_instance); // unsure about that one
    tft.initBus();
  }

[windorey]

Garbled image on display

Edit: I changed the frequency to 40000000, and it is working normally, just limited to ~33Hz
60000000 also yields a max refresh rate of ~33Hz

[lovyan03]

The ESP32 SPI can only choose 80 MHz divided by an integer.
The M5Stack LCD does not have a proven track record of stable operation at 80 MHz.
Therefore, a setting of 40 MHz is the optimal value.

[windorey]

Thank you very much for your reply.