In the code I wrote, it is very straightforward being initialising USART2, receiving a character from a serial monitor and turning on/off an LED based on the character received. The LED does not turn on, in this case when I type the letter 'y' on putty or any other terminal.
With this being said, if I write a simple echo program using USART2 to receive a character from the terminal and send the same character back it works. So i'm not sure why when i'm trying to receive a char without transmitting anything it doesn't work.
#include "stm32f303xe.h"
void USART2_Init(void);
void GPIO_LED_Init(void);
char USART_Read(void);
int main ()
{
//int ch = 0;
USART2_Init();
GPIO_LED_Init();
while (1)
{
//ch = USART_Read();
if (USART_Read() == 'y')
GPIOA->BSRR = (1 << 5);
else
{
//GPIOA->ODR ^= (1 << 5);
GPIOA->BSRR = (1 << 21);
for (int i=0; i<5000; i++);
}
}
}
void USART2_Init(void)
{
// Enable USART 2
RCC->APB1ENR |= (1 << 17);
// Turn on Port A clock for USART pins PA2 (TX) and PA3 (RX)
RCC->AHBENR |= (1 << 17);
// Set PA2 (TX) and PA3 (RX) as Alternate Functions
GPIOA->MODER |= (0x2 << 6) | (0x2 << 4);
// Conifgure Alternate Function Register for PA2 and PA3
GPIOA->AFR[0] |= (0x7 << 12) | (0x7 << 8);
USART2->BRR = 0x341; // Set baud rate to 9600 (8Mhz/9600)
USART2->CR1 |= (1 << 2); // Enable reciever
USART2->CR1 |= (1 << 0); // Enable USART2
}
void GPIO_LED_Init(void)
{
// Turn on clock for GPIO A (LED is connected to PA5)
//RCC->AHBENR |= (1 << 17);
// configure PA5 to General Purpose Output Mode
GPIOA->MODER |= (~(1 << 11)) | (1 << 10);
}
char USART_Read(void)
{
while (!(USART2->ISR & (1 << 5))){} // Check to see if recieve data register is empty
return USART2->RDR; // Load TX data register with ch
}
