I have a problem where Im developing a bare metal USART Send Data for stm32f302r8 nucleo board. Im sending on USART2 which is PA2 and PA3 through the virtual COM. The TDR register is updating 1 byte by 1 byte. But, the TeraTerm is not showing any data. I have checked the nucleo board datasheet where the Virtual COM is enabled by default and I dont think I need to do any rework on the board.
Here is my application code:
/*
* uart_tx.c
*
* Created on: 22 Oct 2023
* Author: irsyad
*/
#include <string.h>
#include "stm32f30xx.h"
#include <stdio.h>
USART_Handle_t usart2_handle;
// tx buffer
uint8_t msg[1024] = "USART Tx testing...........\n\r";
void delay(void)
{
for (uint32_t i = 0; i < 200000; i++);
}
void USART2_GPIOInit(void)
{
GPIO_Handle_t usart2_pins;
usart2_pins.pGPIOx = GPIOA;
usart2_pins.GPIO_PinConfig.GPIO_PinAltFunMode = GPIO_MODE_ALTFN;
usart2_pins.GPIO_PinConfig.GPIO_PinOPType = GPIO_OP_TYPE_PP;
usart2_pins.GPIO_PinConfig.GPIO_PinPuPdControl = GPIO_PU;
usart2_pins.GPIO_PinConfig.GPIO_PinAltFunMode = 7;
usart2_pins.GPIO_PinConfig.GPIO_PinSpeed = GPIO_SPEED_HIGH;
//TX
usart2_pins.GPIO_PinConfig.GPIO_PinNumber = GPIO_PIN_NO_2;
GPIO_Init(&usart2_pins);
//RX
usart2_pins.GPIO_PinConfig.GPIO_PinNumber = GPIO_PIN_NO_3;
GPIO_Init(&usart2_pins);
}
void USART2_Init()
{
usart2_handle.pUSARTx= USART2;
usart2_handle.USART_Config.USART_Baud = USART_STD_BAUD_115200;
usart2_handle.USART_Config.USART_HWFlowControl = USART_HW_FLOW_CTRL_NONE;
usart2_handle.USART_Config.USART_Mode = USART_MODE_ONLY_TX;
usart2_handle.USART_Config.USART_NoOfStopBits = USART_STOPBITS_1;
usart2_handle.USART_Config.USART_WordLength = USART_WORDLEN_8BITS;
usart2_handle.USART_Config.USART_ParityControl = USART_PARITY_DISABLE;
USART_Init(&usart2_handle);
}
void GPIO_ButtonInit(void)
{
//1. first create a variable for our GPIO handle
GPIO_Handle_t GpioBtn; //GpioLed;
/*======================PUSH BUTTON CONFIGURATION===========================*/
//1. now, we have to initialize
//mula2 select port
GpioBtn.pGPIOx= GPIOC;
//2. Then select pin number
GpioBtn.GPIO_PinConfig.GPIO_PinNumber = GPIO_PIN_NO_13;
//3.Select pin mode
GpioBtn.GPIO_PinConfig.GPIO_PinMode = GPIO_MODE_INPUT;
//4.Select speed (ni xpenting sgt, boleh biar default)
GpioBtn.GPIO_PinConfig.GPIO_PinSpeed = GPIO_SPEED_HIGH;
//5. enable internal resistor sebab output type open drain
GpioBtn.GPIO_PinConfig.GPIO_PinPuPdControl = GPIO_NO_PUPD;
//6.enable peripheral clock
GPIO_PeriClockControl(GPIOC, ENABLE);
//7.Call GPIO_init()
GPIO_Init(&GpioBtn); //send address GpioLed
/*======================PUSH BUTTON CONFIGURATION===========================*/
}
int main()
{
GPIO_ButtonInit();
USART2_GPIOInit();
USART2_Init();
USART_PeripheralControl(USART2, ENABLE);
while (1)
{
// wait for button press
while(GPIO_ReadFromInputPin(GPIOC, GPIO_PIN_NO_13) );
delay();
// send some data to the slave
USART_SendData(&usart2_handle, (uint8_t *)msg, strlen((char *)msg));
}
return 0;
}
and here is my USART Send data API:
void USART_SendData(USART_Handle_t *pUSARTHandle, uint8_t *pTxBuffer, uint32_t Len)
{
uint16_t *pdata;
//1.loop over until 'Len' number of bytes are transferred.
for(uint32_t i = 0;i < Len;i++)
{
//2.wait until TXE flag is set in the ISR (It indicates the data is ready at the shift register)
while(! USART_GetFlagStatus(pUSARTHandle->pUSARTx,USART_FLAG_TXE));
//3.Check the USART_WordLength item for 9BIT or 8BIT in a frame
if(pUSARTHandle->USART_Config.USART_WordLength == USART_WORDLEN_9BITS)
{
//if 9BIT, then we have to load 9 bit to the DR.
// to extract 9 bits, we use masking.
//Bit masking is a technique that involves performing bitwise operations on data blocks to extract the required bits
//0x01FF is used to mask out 9bits from the 16bit data.
pdata = (uint16_t*) pTxBuffer;//This is why pTxBuffer is typecasted to 16bit to extract 2bytes of data which only 9bit are loaded into the data register
pUSARTHandle->pUSARTx->TDR = (*pdata & (uint16_t)0x01FF);
//references:https://fastbitlab.com/microcontroller-embedded-c-programming-lecture-116-bit-extraction/
//check for USART_ParityControl
if(pUSARTHandle->USART_Config.USART_ParityControl == USART_PARITY_DISABLE)
{
//If the parity is disabled,
//No parity is used in this transfer. so, 9bits of user data will be sent
//So, its like sending 2bytes, sbb utk hold 9 bits, it requires 2 bytes size.
//hence, increment pTxBuffer twice
pTxBuffer++; //1byte
pTxBuffer++; //1byte
}
else
{
//Parity bit is used in this transfer . so , 8bits of user data will be sent
//The 9th bit will be replaced by parity bit by the hardware
pTxBuffer++; //1byte
}
}
else
{
//8-bit data transfer
//Doing this (bitwise AND with 0xFF) ensures that only 8-bits are taken from pTxBuffer.
pUSARTHandle->pUSARTx->TDR = (*pTxBuffer & (uint8_t)0xFF);
//increment the buffer address
pTxBuffer++;
}
}
//4.wait until TC flag is set in the ISR
while( ! USART_GetFlagStatus(pUSARTHandle->pUSARTx,USART_FLAG_TC));
}
Anyone knows the solution?
