USART NOT receiving nothing

[timothy]

Posted on August 07, 2013 at 07:12

Im using usart2 and i know its sending data but will not receive im using :

rx_data = USART_ReceiveData(USART2);to save the data then using a while(rx_data > 0 ) { do stuff}any suggestions about why its not receiving? #poorly-framed-question #usart #usart-stm32f103

[jpeacock2399]

Posted on August 07, 2013 at 15:46

Are you first checking the RXNE flag to see if data is available before trying to read it from the USART?

  Jack Peacock

[timothy]

Posted on August 07, 2013 at 18:07

yes i use

while( USART_GetFlagStatus(USART2, USART_FLAG_RXNE) == SET); // checking flag 
{rx_data = USART_ReceiveData(USART2);
}

then once rx_data >0 it does stuff, but i dont understand why it doesnt react. Im feeding the USART2.TX right into the USART2.RX. Am i doing something wrong?

[Tesla DeLorean]

Posted on August 07, 2013 at 18:56

Am i doing something wrong?

Evidently, perhaps some more details about how you've initialized things, and how they are connected. You probably want

while( USART_GetFlagStatus(USART2, USART_FLAG_RXNE) == RESET);

if you want it to spin while NOT asserted

[developer2]

Posted on August 07, 2013 at 19:00

did you set USART mode:

 USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;  and both USART GPIO pins as AF ?

[timothy]

Posted on August 07, 2013 at 20:40

GPIO_InitTypeDef GPIO_InitStructure; // GPIO structure
USART_InitTypeDef USART_InitStructure; // USART Structure
RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1 | RCC_APB2Periph_GPIOA, ENABLE);
RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART2, ENABLE);
/* Configure USART Tx as alternate function push/pull */
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2; //PA9-UART.TX
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_Init(GPIOA, &GPIO_InitStructure);
/* Configure USART Rx as input floating */
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_3;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
GPIO_Init(GPIOA, &GPIO_InitStructure);
// USART Configure
USART_InitStructure.USART_BaudRate = 9600;
USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
USART_InitStructure.USART_Mode = USART_Mode_Tx | USART_Mode_Rx;
USART_InitStructure.USART_Parity = USART_WordLength_8b;
USART_InitStructure.USART_StopBits = USART_StopBits_1;
USART_InitStructure.USART_WordLength = USART_Parity_No;
USART_Init(USART2, &USART_InitStructure);
USART_ITConfig(USART2, USART_IT_RXNE, ENABLE);
USART_Cmd(USART2, ENABLE);

Here is how i initialized everything. After further testing it works once and stops. while( USART_GetFlagStatus(USART2, USART_FLAG_RXNE) == RESET) { do stuff} Any ideas why it would stop? the do stuff mentioned here works already im just trying to have it work only when USART is receiving data.

[Tesla DeLorean]

Posted on August 07, 2013 at 21:42

Don't enable the RXNE interrupt.

If you're using an interrupt, you a) need to initialize NVIC also, and b) have a service routine to handle it.