stm32f4 USART2 problem

[d4ng3r09]

Posted on June 04, 2015 at 22:37

I am trying to use pb8 and pb9 with stm32f4 's usart 2 peripheral.I first used usart 2 with pb6 and pb7.It worked great but then i was obliged to change them. to pb8 and pb9.

Here a quick look at my code.

#include ''stm32f4xx.h''
#include ''stm32f4xx_usart.h''
#include ''stm32f4xx_gpio.h''
#include ''stm32f4xx_rcc.h''
#include ''misc.h''
#include <
string.h
>
#include <
stdlib.h
>
/* Private variables ---------------------------------------------------------*/
//UART connection
void UARTSend(const unsigned char * pucBuffer, unsigned long ulCount);
volatile char received_string[20 + 1]; // this will hold the recieved string
int main(void) {
unsigned char welcome_str[] = ''xxyyzz'';
u8 loop = 1;
char X[8] = ''aaaaaa'';
char Y[8] = ''aaaaaa'';
int length = 0;
int i = 2;
int findY = 0;
int y = 0;
init_USART2(9600);
while (loop) {
if (Full == 1) {
ExtracTData(received_string);
}
}
//UARTSend(welcome_str, sizeof(welcome_str));
USART_Cmd(USART2, DISABLE);
}
void UARTSend(const unsigned char *pucBuffer, unsigned long ulCount) {
//
// Loop while there are more characters to send.
//
while (ulCount--) {
while (USART_GetFlagStatus(USART2, USART_FLAG_TXE) == RESET) {
}
USART_SendData(USART2, (uint8_t) * pucBuffer++);
/* Loop until the end of transmission */
}
}
void init_USART2(uint32_t baudrate) {
GPIO_InitTypeDef GPIO_InitStruct; // this is for the GPIO pins used as TX and RX
USART_InitTypeDef USART_InitStruct; // this is for the USART2 initilization
NVIC_InitTypeDef NVIC_InitStructure; // this is used to configure the NVIC (nested vector interrupt controller)
RCC_APB2PeriphClockCmd(RCC_APB1Periph_USART2, ENABLE);
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);
GPIO_InitStruct.GPIO_Pin = GPIO_Pin_2 | GPIO_Pin_3; // Pins 6 (TX) and 7 (RX) are used
GPIO_InitStruct.GPIO_Mode = GPIO_Mode_AF; // the pins are configured as alternate function so the USART peripheral has access to them
GPIO_InitStruct.GPIO_Speed = GPIO_Speed_50MHz; // this defines the IO speed and has nothing to do with the baudrate!
GPIO_InitStruct.GPIO_OType = GPIO_OType_PP; // this defines the output type as push pull mode (as opposed to open drain)
GPIO_InitStruct.GPIO_PuPd = GPIO_PuPd_NOPULL; // this activates the pullup resistors on the IO pins
GPIO_Init(GPIOA, &GPIO_InitStruct); // now all the values are passed to the GPIO_Init() function which sets the GPIO registers
GPIO_PinAFConfig(GPIOA, GPIO_PinSource2, GPIO_AF_USART2); //
GPIO_PinAFConfig(GPIOA, GPIO_PinSource3, GPIO_AF_USART2);
USART_InitStruct.USART_BaudRate = 9600;
USART_InitStruct.USART_WordLength = USART_WordLength_8b;
USART_InitStruct.USART_StopBits = USART_StopBits_1;
USART_InitStruct.USART_Parity = USART_Parity_No;
USART_InitStruct.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
USART_InitStruct.USART_Mode = USART_Mode_Tx | USART_Mode_Rx;
USART_Init(USART2, &USART_InitStruct);
USART_ITConfig(USART2, USART_IT_RXNE, ENABLE);
NVIC_InitStructure.NVIC_IRQChannel = USART2_IRQn; // we want to configure the USART2 interrupts
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0; // this sets the priority group of the USART2 interrupts
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0; // this sets the subpriority inside the group
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; // the USART2 interrupts are globally enabled
NVIC_Init(&NVIC_InitStructure); // the properties are passed to the NVIC_Init function which takes care of the low level stuff
// finally this enables the complete USART2 peripheral
USART_Cmd(USART2, ENABLE);
}
void USART2_IRQHandler(void) {
// check if the USART2 receive interrupt flag was set
if (USART_GetITStatus(USART2, USART_IT_RXNE)) {
static uint8_t cnt = 0; // this counter is used to determine the string length
char t = USART2->DR; // the character from the USART2 data register is saved in t
/* check if the received character is not the LF character (used to determine end of string)
* or the if the maximum string length has been been reached
*/
if ((t != '\n') && (cnt < 20)) {
received_string[cnt] = t;
cnt++;
} else { // otherwise reset the character counter
cnt = 0;
Full = 1;
}
}
}

[Tesla DeLorean]

Posted on June 04, 2015 at 22:58

I am trying to use pb8 and pb9 with stm32f4 's usart 2 peripheral.I first used usart 2 with pb6 and pb7.It worked great but then i was obliged to change them. to pb8 and pb9.

Here a quick look at my code.Your code doesn't reflect any of those configurations, and PB8/9 have no USART associativity. The Data Sheet is the controlling document here.

[d4ng3r09]

Posted on June 05, 2015 at 08:46

My bad .I am trying to use actually PA2 and PA3 with usart 2.(sorry for that  i confounded with something else i did lately).