You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
59 lines
1.5 KiB
C
59 lines
1.5 KiB
C
#include "stm32c031xx.h" // CMSIS-compatible interface
|
|
#include "delay.h"
|
|
|
|
// LED marked "LD4" on the NUCLEO-C031C6 board
|
|
#define LD4_PIN 5U
|
|
|
|
// external LED to be inserted between GND (short leg) and
|
|
// D12 (longer leg) on the CN9 connector
|
|
#define LD5_PIN 6U
|
|
|
|
unsigned fact(unsigned n); // prototype
|
|
|
|
int main(void) {
|
|
unsigned volatile x;
|
|
|
|
x = fact(0U);
|
|
x = 2U + 3U*fact(1U);
|
|
(void)fact(5U);
|
|
|
|
// enable GPIOA clock port for the LEDs
|
|
RCC->IOPENR |= (1U << 0U);
|
|
|
|
// NUCLEO-C031C6 board has LED LD4 on GPIOA pin LD4_PIN
|
|
// and external LED LD5 on GPIO LD5_PIN
|
|
// set the LED pins as push-pull output, no pull-up, pull-down
|
|
GPIOA->MODER &= ~((3U << 2U*LD4_PIN) | (3U << 2U*LD5_PIN));
|
|
GPIOA->MODER |= ((1U << 2U*LD4_PIN) | (1U << 2U*LD5_PIN));
|
|
GPIOA->OTYPER &= ~((1U << LD4_PIN) | (1U << LD5_PIN));
|
|
GPIOA->OSPEEDR &= ~((3U << 2U*LD4_PIN) | (3U << 2U*LD5_PIN));
|
|
GPIOA->OSPEEDR |= ((1U << 2U*LD4_PIN) | (1U << 2U*LD5_PIN));
|
|
GPIOA->PUPDR &= ~((3U << 2U*LD4_PIN) | (3U << 2U*LD5_PIN));
|
|
|
|
GPIOA->BSRR = (1U << LD5_PIN); // turn LD5 on
|
|
|
|
while (1) { // endless loop
|
|
GPIOA->BSRR = (1U << LD4_PIN); // turn LD4 on
|
|
|
|
delay(500000);
|
|
|
|
GPIOA->BSRR = (1U << (LD4_PIN + 16U)); // turn LD4 off
|
|
|
|
delay(250000);
|
|
}
|
|
//return 0; // unreachable code
|
|
}
|
|
|
|
unsigned fact(unsigned n) {
|
|
// 0! = 1
|
|
// n! = n*(n-1)! for n > 0
|
|
|
|
if (n == 0U) {
|
|
return 1U;
|
|
}
|
|
else {
|
|
return n * fact(n - 1U);
|
|
}
|
|
}
|
|
|