c – Trying to control step motor with LCD and Raspberry Pi Pico 2

I have an LCD touchscreen connected to my Raspberry Pi Pico 2. My goal is to detect a touch on the screen and, when the user taps it, start spinning a stepper motor. The motor is controlled through GPIO pins.

The problem I am facing is that the stepper motor is spinning much slower than expected after the touch event. I am not sure if the issue is related to the way I am driving the motor, the delay between steps, or the way the touchscreen interaction is handled in the code.

I would like the motor to start spinning immediately and at a higher speed after the screen is touched. What might be causing the motor to run so slowly and how I could improve the performance?

#include 
#include "pico/stdlib.h"

#include "tft_lcd_ili9341/gfx/gfx_ili9341.h"
#include "tft_lcd_ili9341/ili9341/ili9341.h"
#include "tft_lcd_ili9341/touch_resistive/touch_resistive.h"

#include "image_bitmap.h"           


#define SCREEN_ROTATION 1           
const int width = 320;             
const int height = 240;            

const int BOBINAS[4] = {5, 4, 3, 2};


const int  rotImgPosX = (width - 32) / 2;
const int  rotImgPosY = (height - 24) / 2;


int f_btn = 0;
volatile int motor_state = 0;
volatile int imagem_state = 0;


void ledButtonCallback(GFX_Button *btn) {
    f_btn = 1;
}


int direcao = 1;

void drawImagem(int estado) {
    gfx_fillRect(rotImgPosX, rotImgPosY, 32, 24, 0x0000);
    if (direcao == 1){ //horario
        if (estado == 0)
        gfx_drawBitmap(rotImgPosX, rotImgPosY, horario_1, 24, 32, 0xFFFF); 
    else if(estado == 1)
        gfx_drawBitmap(rotImgPosX, rotImgPosY, horario_2, 32, 24, 0xFFFF);
    else if (estado == 2)
        gfx_drawBitmap(rotImgPosX, rotImgPosY, horario_3, 24, 32, 0xFFFF); 
    else if (estado == 3)
        gfx_drawBitmap(rotImgPosX, rotImgPosY, horario_4, 32, 24, 0xFFFF); 
        
    }
    else if (direcao == -1){ //æntihorario
        if (estado == 0)
        gfx_drawBitmap(rotImgPosX, rotImgPosY, anti_horario_4, 32, 24, 0xFFFF); 
    else if(estado == 1)
        gfx_drawBitmap(rotImgPosX, rotImgPosY, anti_horario_3, 24, 32, 0xFFFF); 
    else if (estado == 2)
        gfx_drawBitmap(rotImgPosX, rotImgPosY, anti_horario_2, 32, 24, 0xFFFF); 
    else if (estado == 3)
        gfx_drawBitmap(rotImgPosX, rotImgPosY, anti_horario_1, 24, 32, 0xFFFF); 
    }
    
    
}

bool timer_motor_callback(struct repeating_timer *t) {
    motor_state = 1; // Alterna o estado do motor    
    return true; // Retorna true para continuar o timer
}

bool timer_imagem_callback(struct repeating_timer *t) {
    imagem_state = 1;
    return true;
}


int main() {
    repeating_timer_t timer_motor;
    repeating_timer_t timer_imagem;

    stdio_init_all();

    for (int i = 0; i < 4; i++) {
        gpio_init(BOBINAS[i]);
        gpio_set_dir(BOBINAS[i], GPIO_OUT);
    }



    
    LCD_initDisplay();
    LCD_setRotation(SCREEN_ROTATION);   

    
    configure_touch();                  
  
    gfx_init();                        
    gfx_clear();                      

    gfx_setTextSize(2);                                 
    gfx_setTextColor(0x07E0);                           

    gfx_drawText(
        width/6,                                       
        10,                                             
        "PicoDock LED Toggle"                           
    );
 

    
    GFX_Button ledButton = {            
        .x = rotImgPosX,                
        .y = rotImgPosY,                
        .w = 32,                        
        .h = 32,                        
        .callback = ledButtonCallback   
    };

    gfx_registerButton(&ledButton);     

    int i = 0;
    int motor_on = 0;
    int img = 0;

    drawImagem(img);
    
    add_repeating_timer_us(1000, timer_motor_callback, NULL, &timer_motor);
    add_repeating_timer_ms(500, timer_imagem_callback, NULL, &timer_imagem);

    while (true) {
        int touchRawX, touchRawY;               
        int screenTouchX, screenTouchY  = 0;    

        int touchDetected = readPoint(&touchRawX, &touchRawY);  
                                                                

        if (touchDetected)  {                                                       
            gfx_touchTransform(SCREEN_ROTATION,                 
                               touchRawX, touchRawY,            
                               &screenTouchX, &screenTouchY);

                                                                           
            gfx_updateButtons(screenTouchX, screenTouchY, touchDetected);   
                                                                                  
        }

        if (f_btn) {

            direcao = -direcao; 
            motor_on = 1;
            drawImagem(img);    
            f_btn = 0;
        }

        
        
        if (motor_state && motor_on) {
            motor_state = 0;

            for (int k = 0; k < 4; k++) {
                gpio_put(BOBINAS[k], 0);
            }

            if (direcao == 1){
                gpio_put(BOBINAS[i], 1);
            }
                
            else {
                gpio_put(BOBINAS[3 - i], 1);
            }
                

            i = (i + 1) % 4;
        
    
        }

        if (imagem_state && motor_on) {
            imagem_state = 0;
            img = (img + 1) % 4;
            drawImagem(img);
        }
        
    }

    return 0;
}