Example of double buffer and DMA using RP2040 and TFT_SPI on v9

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1

Description

Hi, I need an example of LVGL v9.x on an Pi Pico using double buffer with DMA on an TFT_eSPI 2.4.
I think is an easy thing for someone that knows, but examples like this are needed for noobs like me.
RP2040 struggle to render UIs in LVGL, so every optimization is needed. I even overclocked it to 250MHz, but is lacking still.

What do you want to achieve?

To have a base to make my UIs, and run well.

What have you tried so far?

I have an example of v8 but v9 is very different.

2

Can you share a V8 sample?

3 
#include <Arduino.h>
#include <SPI.h>
#include <TFT_eSPI.h>
TFT_eSPI tft = TFT_eSPI(); /* TFT entity */

/**************************LVGL and UI************************
if you want to use the LVGL demo. you need to include <demos/lv_demos.h> and <examples/lv_examples.h>.
if not, please do not include it. It will waste your Flash space.
**************************************************************/
#include <demos/lv_demos.h>
#include <lvgl.h>
// #include <examples/lv_examples.h>
/**************************LVGL and UI END************************/

/*******************************************************************************
 * Please define the corresponding macros based on the board you have purchased.
 * CrowPanel_24 means CrowPanel Pico Display 2.4inch Board
 * CrowPanel_28 means CrowPanel Pico Display 2.8inch Board
 * CrowPanel_35 means CrowPanel Pico Display 3.5inch Board
 ******************************************************************************/
#define CrowPanel_24
// #define CrowPanel_28
// #define CrowPanel_35

#if defined(CrowPanel_35)
/*screen resolution*/
static const uint16_t screenWidth = 480;
static const uint16_t screenHeight = 320;
uint16_t calData[5] = {192, 3590, 335, 3362, 1};
#elif defined(CrowPanel_24)
static const uint16_t screenWidth = 320;
static const uint16_t screenHeight = 240;
uint16_t calData[5] = {412, 3388, 380, 3303, 3};
#elif defined(CrowPanel_28)
static const uint16_t screenWidth = 320;
static const uint16_t screenHeight = 240;
uint16_t calData[5] = {208, 3520, 380, 3373, 1};
#endif

static lv_disp_draw_buf_t draw_buf;
static lv_color_t *buf1[screenWidth * screenHeight / 6];
static lv_color_t *buf2[screenWidth * screenHeight / 6];  // Second buffer for dual buffering

//_______________________
/* display flash */
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.pushImageDMA(area->x1, area->y1, w, h, (uint16_t *)&color_p->full);  // Use DMA for pushing colors
  tft.endWrite();

  lv_disp_flush_ready(disp);
}

uint16_t touchX, touchY;
/*touch read*/
void my_touchpad_read(lv_indev_drv_t *indev_driver, lv_indev_data_t *data) {
  bool touched = tft.getTouch(&touchX, &touchY, 600);
  if (!touched) {
    data->state = LV_INDEV_STATE_REL;
  }
  else {
    data->state = LV_INDEV_STATE_PR;

    /*set location*/
    data->point.x = touchX;
    data->point.y = touchY;

    Serial1.print("Data x ");
    Serial1.print(touchX);
    Serial1.print(" - ");

    Serial1.print("Data y ");
    Serial1.println(touchY);
  }
}

void setup() {
  delay(100);  // while (!Serial) { delay(10);}
  Serial1.begin(921600);
  Serial1.println(F("Starting..."));

  // Display Prepare
  tft.begin();
  tft.setRotation(3);
  tft.setTouch(calData);
  Serial1.println(tft.initDMA());

  // lvgl init
  lv_init();

  lv_disp_draw_buf_init(&draw_buf, buf1, buf2, screenWidth * screenHeight / 6);

  /* Initialize the display */
  static lv_disp_drv_t disp_drv;
  lv_disp_drv_init(&disp_drv);
  /* Change the following line to your display resolution */
  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);

  /* Initialize the (dummy) input device 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);

  tft.fillScreen(TFT_BLACK);

  lv_demo_benchmark();  // LVGL demo
  // lv_demo_widgets();

  Serial1.println("Setup done");
}

void loop() {
  lv_timer_handler();
  delay(5);
}
4

This is a rather complex example using this specific driver, and I wanted an example using the general Bodmer drivers, https://github.com/Bodmer/TFT_eSPI/

I think that that the example in v9 can be as simple as the one I posted, without the need for low-level fiddling.