Hey guys,
I have NUCLEO-WL55JC2 board, and I am following a tutorial to learn baremetal embedded programming. The first task is a "hello world" app for UART.
So, I just read the doc, and I understood that I need to use LPUART1 which is the default for this board.
But, I could not get any character over COM port. Can you please help me?
#include "stm32wl55xx.h"
#define RCC_GPIOA_EN (1U<<0)
#define RCC_GPIOB_EN (1U<<1)
#define RCC_GPIOC_EN (1U<<2)
#define LPUART1_EN (1U<<0)
#define CR1_TE (1U<<3)
#define ISR_TXE (1U<<7)
//#define SYS_FREQ 48000000
//#define APB1_CLK SYS_FREQ
#define UART_BAUDRATE 9600
static void uart_set_baudrate(USART_TypeDef *USARTx, uint32_t PeriphClk, uint32_t Baudrate);
static uint16_t compute_uart_bd(uint32_t PeriphClk, uint32_t Baudrate);
void uart1_tx_init(void);
void uart1_write(int ch);
int main(void)
{
uart1_tx_init();
while(1)
{
uart1_write("Y");
}
for(int i=0;i<1000000;i++){}
}
void uart1_tx_init(void)
{
/***** Configure UART GPIO Pin *****/
/* Enable clock access to the proper GPIO, in this case GPIOA */
RCC->AHB2ENR |= RCC_GPIOA_EN;
/* Set PA2 mode to alternate function mode */
GPIOA->MODER |= (1U<<5);
GPIOA->MODER &=~(1U<<4);
/* Set PA2 alternate function type to LPUART_TX (AF08) */
GPIOA->AFR[0] &=~(1U<<8);
GPIOA->AFR[0] &=~(1U<<9);
GPIOA->AFR[0] &=~(1U<<10);
GPIOA->AFR[0] |= (1U<<11);
/***** Configure UART Module *****/
/* Enable clock access to LPUART1 */
RCC->APB1ENR2 |= LPUART1_EN;
/* Configure baud rate */
LPUART1->BRR = 0x369; //9600 in the doc
/* Configure the transfer direction */
LPUART1->CR1 |= CR1_TE;
/* Enable LPUART1 */
LPUART1->CR1 |= (1U<<0);
}
void uart1_write(int ch)
{
/* Make sure the transmit data reg is empty */
while(!(LPUART1->ISR & ISR_TXE)){}
/* Write to transmit data reg */
LPUART1->TDR = (ch & 0xFF);
}
