usart_basic.c

ID:438072 · 发表于 2018-12-3 03:10

#include "stm32f10x.h"

#define NVIC_PRIORITYGROUP_4 3

void TIM1_UP_IRQHandler(void);
void usartSetup (void);
int SendChar (int ch);
int GetChar (void);

__IO uint16_t i = 0x30;
int characterRx;

int main(void)
{
RCC->APB2ENR |= RCC_APB2ENR_IOPAEN;
RCC->APB2ENR |= RCC_APB2ENR_TIM1EN;
   RCC->APB2ENR |= RCC_APB2ENR_USART1EN;

// PA5 configuration (Digital Output, push-pull, max speed: 50 MHz)
   GPIOA->CRL &= ~GPIO_CRL_CNF5_0;
   GPIOA->CRL &= ~GPIO_CRL_CNF5_1;
   GPIOA->CRL |=  GPIO_CRL_MODE5_0;
   GPIOA->CRL |=  GPIO_CRL_MODE5_1;
   // PA1 configuration (Digital Input, push-pull)
   GPIOA->CRL &= ~GPIO_CRL_CNF1_0;
   GPIOA->CRL |=  GPIO_CRL_CNF1_1;
   GPIOA->CRL &= ~GPIO_CRL_MODE1_0;
   GPIOA->CRL &= ~GPIO_CRL_MODE1_1;

NVIC_SetPriorityGrouping(NVIC_PRIORITYGROUP_4);
NVIC_SetPriority (TIM1_UP_IRQn, 1);

NVIC_EnableIRQ(TIM1_UP_IRQn);
TIM1->PSC = 999;          /* 36 MHz -> 36E6/1E3 = 36E3 Hz */
TIM1->ARR = 36000;       /* 36E3/36E3 = 1 Hz */
TIM1->DIER |= TIM_DIER_UIE; /* interrupt on update */
TIM1->CR1  |= TIM_CR1_CEN; /* enable */

   usartSetup ();

while (1)
   {

}
/* return 0; */
}

void TIM1_UP_IRQHandler(void)
{
TIM1->SR &= ~TIM_SR_UIF;

   GPIOA->ODR ^= 1<<5;

   SendChar(i);
   i++;
   if (i == 0x80)
   i = 0x30;
   characterRx= GetChar();
}

void usartSetup (void) {

   // make sure the relevant pins are appropriately set up.
   // PA9 <- USART1_TX
   GPIOA->CRH &= ~GPIO_CRH_CNF9_0;  // GPIO_Mode_AF_PP
   GPIOA->CRH |=  GPIO_CRH_CNF9_1;
   GPIOA->CRH |=  GPIO_CRH_MODE9_0; // GPIO_Speed_50MHz
   GPIOA->CRH |=  GPIO_CRH_MODE9_1;

// PA10 <- USART1_RX
   GPIOA->CRH &= ~GPIO_CRH_CNF10_0; // GPIO_Mode_IN_FLOATING
   GPIOA->CRH |= GPIO_CRH_CNF10_1;
   GPIOA->CRH &= ~GPIO_CRH_MODE10_0; // Don't care
   GPIOA->CRH &= ~GPIO_CRH_MODE10_1;

  RCC->APB2ENR |= RCC_APB2ENR_USART1EN; // enable clock for USART1
  USART1->BRR = 72000000L/115200L; // set baudrate
  USART1->CR1 |= (USART_CR1_RE | USART_CR1_TE); // RX, TX enable
  USART1->CR1 |= USART_CR1_UE; // USART enable
  }

Int SendChar (int ch) {
  While (!(USART1->SR & USART_SR_TXE));
  USART1->DR = (ch & 0xFF);
  Return (ch);
}

Int GetChar (void) {
  While (!(USART1->SR & USART_SR_RXNE));
  Return ((int)(USART1->DR & 0xFF));
}

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