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#include <libopencm3/stm32/rcc.h>
#include <libopencm3/stm32/gpio.h>
#include <libopencm3/stm32/usart.h>
#define DELAY 1000000
void clock_init(void);
void gpio_init(void);
void usart_init(void);
void delay(void);
int main(void)
{
clock_init();
gpio_init();
usart_init();
while(1){
delay();
usart_send_blocking(USART3, 'H');
usart_send_blocking(USART3, 'e');
usart_send_blocking(USART3, 'l');
usart_send_blocking(USART3, 'l');
usart_send_blocking(USART3, 'o');
usart_send_blocking(USART3, '\r');
usart_send_blocking(USART3, '\n');
delay();
}
return 0;
}
void clock_init(void)
{
rcc_periph_clock_enable(RCC_GPIOB); // for USART3
rcc_periph_clock_enable(RCC_USART3); // for USART3
}
void gpio_init(void)
{
gpio_set_mode(GPIOB, GPIO_MODE_OUTPUT_50_MHZ, GPIO_CNF_OUTPUT_ALTFN_PUSHPULL, GPIO_USART3_TX); // TX setup
gpio_set_mode(GPIOB, GPIO_MODE_INPUT, GPIO_CNF_INPUT_FLOAT, GPIO_USART3_RX); // RX setup
}
void usart_init(void)
{
usart_set_baudrate(USART3, 9600);
usart_set_databits(USART3, 8);
usart_set_flow_control(USART3, USART_FLOWCONTROL_NONE);
usart_set_mode(USART3, USART_MODE_TX_RX);
usart_set_parity(USART3, USART_PARITY_NONE);
usart_set_stopbits(USART3, USART_STOPBITS_1);
usart_enable(USART3);
}
void delay(void)
{
for (int i = 0; i < DELAY; i++) {
__asm__("nop");
}
}
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