STM32 button control LED (without firmware library)

       The STM32F407ZET6 is used. The four pins of the controlled LED lights are LED0 -> PF9, LED1 -> PF10, LED2-> PE13, LED3 -> PE14. The four pins of the buttons are KEY0--> PA0, KEY1--> PE2, KEY2--> PE3, KEY3--> PE4.

       In the loop, determine whether the button is pressed (the corresponding pin input will become 0). If it is pressed, the corresponding LED pin will output a low level and light up.

    1. Initialize the registers of LED lights and buttons respectively.

Initialize the LED light (set various registers): set the GPIO clock, configure the mode register (general output type), configure the output type (set to output push), set the register that controls the output rate, and finally configure the output data register (let the LED light be off by default)

Initialize the buttons (set various registers): set the GPIO clock, configure the key register (set to input mode), and set the register that controls the output rate.

     2. In the main function, keep checking whether the button is pressed (whether the corresponding pin level is 0)

The function is implemented as follows:

#define rRCCAHB1CLKEN   *((volatile unsigned long *)0x40023830) 

#define rGPIOF_MODER  *((volatile unsigned long *)0x40021400)   

#define rGPIOF_OTYPER *((volatile unsigned long *)0x40021404) 

#define rGPIOF_OSPEEDR  *((volatile unsigned long *)0x40021408) 

#define rGPIOF_IDR  *((volatile unsigned long *)0x40021410) 

#define rGPIOF_ODR  *((volatile unsigned long *)0x40021414) 

#define rGPIOE_MODER  *((volatile unsigned long *)0x40021000)

#define rGPIOE_OTYPER *((volatile unsigned long *)0x40021004)

#define rGPIOE_OSPEEDR  *((volatile unsigned long *)0x40021008)

#define rGPIOE_IDR  *((volatile unsigned long *)0x40021010)

#define rGPIOE_ODR  *((volatile unsigned long *)0x40021014)

#define rGPIOA_MODER  *((volatile unsigned long *)0x40020000)

#define rGPIOA_OTYPER *((volatile unsigned long *)0x40020004)

#define rGPIOA_OSPEEDR  *((volatile unsigned long *)0x40020008)

#define rGPIOA_IDR  *((volatile unsigned long *)0x40020010)

#define rGPIOA_ODR  *((volatile unsigned long *)0x40020014)

void key_init()

{

rRCCAHB1CLKEN |= 1 | (1 << 1);

rGPIOA_MODER&=~(1|(1<<1));

rGPIOF_OSPEEDR &= ~(1 | (1 << 1) );

rGPIOE_MODER&= ~(0x3f<<4);

rGPIOE_MODER &= ~(0x3f<<4);

}

void led_init()

{

rRCCAHB1CLKEN |= (1 << 5) | (1 << 4);

rGPIOF_MODER &= ~((0x3 << 18) | (0x3 << 20));

rGPIOF_MODER |= (1 << 18) | (1 << 20);  

rGPIOF_OTYPER &= ~( (1 << 9) | (1 << 10));

rGPIOF_OSPEEDR &= ~((0x3 << 18) | (0x3 << 20) );

rGPIOF_ODR  |=  (1 << 9 | 1 << 10) ;

rGPIOE_MODER &= ~((0X3 << 26) | (0X3 << 28) );

rGPIOE_MODER |= (1 << 26) | (1 << 28);

rGPIOE_OTYPER &= ~( (1 << 13) | (1 << 14));

rGPIOE_OSPEEDR &= ~((0x3 << 26) | (0x3 << 28) );

rGPIOE_ODR  |=  (1 << 13 | 1 << 14) ;

}

void delay(int i)

{

int v = i;

while(v--);

}

void led_on(int i)

{

if (i == 0)

{

rGPIOF_ODR &= ~(1 << 9);

rGPIOF_ODR |= 1 << 10;

rGPIOE_ODR |= (1 << 13) | (1 << 14);

}

else if (i == 1)

{

rGPIOF_ODR |= (1 << 9);

rGPIOF_ODR &= ~(1 << 10);

rGPIOE_ODR |= (1 << 13) | (1 << 14);

}

else if (i == 2)

{

rGPIOF_ODR |= (1 << 9) | (1 << 10);

rGPIOE_ODR &= ~(1 << 13);

rGPIOE_ODR |= 1 << 14;

}

else if (i == 3)

{

rGPIOF_ODR |= (1 << 9) | (1 << 10);

rGPIOE_ODR &= ~(1 << 14);

rGPIOE_ODR |= 1 << 13;

}

}

int main()

{

int i = 0;

led_heat();

key_init();

while(1)

{

if(!(rGPIOA_IDR&1))

       {

delay(50); //debounce

if(!(rGPIOA_IDR&1))

{

led_on(0);

}

}

else

{

rGPIOF_ODR |= 1 << 9;//µÆÃð

}

if(!(rGPIOE_IDR&(1<<2)))

       {

delay(50);

if(!(rGPIOE_IDR&(1<<2)))

{

led_on(1);

}

}

else

{

rGPIOF_ODR |= 1 << 10;

}

if(!(rGPIOE_IDR&(1<<3)))

       {

delay(50);

if(!(rGPIOE_IDR&(1<<3)))

{

led_on(2);

}

}

else

{

rGPIOE_ODR |= 1 << 13;

}

if(!(rGPIOE_IDR&(1<<4)))

       {

delay(50);

if(!(rGPIOE_IDR&(1<<4)))

{

led_on(3);

}

}

else

{

rGPIOE_ODR |= 1 << 14;

}

}

}