MUI drawing fails in pure C on AVR (empty screen)

[Keri27]

Hello everyone,

I am trying to run a minimal MUI example on an AVR MCU (ATmega328P) using pure C via PlatformIO.

My display initializes correctly, and standard u8g2_DrawStr works perfectly. However, mui_Draw(&mui) renders an empty screen.

I cannot define muif_list globally due to the initializer element is not constant error. Therefore, I moved muif_list inside main() as a local array.

Calling mui_GotoForm(&mui, 1, 0) returns 1 - program displays "Menu OK".

Is it possible that defining muif_list locally inside main() breaks the MUI internal pointer logic in pure C? Does anyone know what I am missing? Any hints would be appreciated!

#include <avr/io.h>
#include <avr/interrupt.h>
#include <stdint.h>
#include <avr/pgmspace.h>

#include "DEP128064C1.h"
#include "u8g2.h"
#include "mui.h"
#include "mui_u8g2.h"

mui_t mui;

// FDS data
const fds_t fds_data[] PROGMEM = 
    MUI_FORM(1)
        MUI_STYLE(0)
            MUI_XYT("BN", 40, 40, " Select Me ");

int main(void)
{
  muif_t muif_list[] = {
    MUIF_U8G2_FONT_STYLE(0, u8g2_font_helvR08_tr),
    MUIF_U8G2_LABEL(),
    MUIF_BUTTON("BN", mui_u8g2_btn_exit_wm_fi)};

  /* 3-wire SPI constructor */
  u8g2_Setup_ssd1306_128x64_noname_f(&u8g2, U8G2_R0, u8x8_byte_3wire_sw_spi, gpio_cb);

  u8g2_InitDisplay(&u8g2);
  u8g2_SetPowerSave(&u8g2, 0);  // switch off power save mode
  u8g2_SetContrast(&u8g2, 150); // <0; 255>

  u8g2_ClearBuffer(&u8g2);
  u8g2_ClearDisplay(&u8g2);

  u8g2_SetDrawColor(&u8g2, 1); // 1 = white
  u8g2_SetFontMode(&u8g2, 1);
  u8g2_SetFont(&u8g2, u8g2_font_courB12_tf);

  mui_Init(&mui, &u8g2, fds_data, muif_list, sizeof(muif_list) / sizeof(muif_t));

  uint8_t form_ok = mui_GotoForm(&mui, 1, 0);
  u8g2_SetFont(&u8g2, u8g2_font_courB12_tf);

  if (form_ok == 1)
  {
    u8g2_DrawStr(&u8g2, 0, 30, "Menu OK!");
  }
  else
  {
    u8g2_DrawStr(&u8g2, 0, 30, "Menu ERROR");
  }

  mui_Draw(&mui);   

  u8g2_SendBuffer(&u8g2);

  while (1)
  {
  }
}

[Keri27]

Addition: My code is inspired by: #2569