USART3 RXNE IT - does not work

[ondrej]

Posted on April 21, 2013 at 18:35

Hello, i need two USARTs working. First one USART1 (TX only) (Used for debugging purposes). Second one USART3 (TX/RX) Write function will send message to another device and waits for answer.

After initialization of both USARTs if i ONLY use one of these USARTs, everything works how i expect. Problem will occur when i send data from USART1(TX work) and after i want to comunicate over USART3. USART3 will TX data, but RXNE interrupt will never occur. Everything was checked with oscilloscope and i know that slave device sent answer to USART3. EDIT: Each USART Init has its own .c file. Global variables are declared as static. USART1 Initialization and IRQ Handler:

void
Debug_Init(
void
)

{

GPIO_InitTypeDef GPIO_InitStructure;

USART_InitTypeDef USART_InitStructure;

NVIC_InitTypeDef NVIC_InitStructure;


vSemaphoreCreateBinary(WriteLock);


Queue_TXComplete = xQueueCreate(10, 
sizeof
(u8));


RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);

RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1, ENABLE);


GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9;

GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;

GPIO_Init(GPIOA, &GPIO_InitStructure);


USART_DeInit(USART1);

USART_InitStructure.USART_BaudRate = 115200;

USART_InitStructure.USART_WordLength = USART_WordLength_8b;

USART_InitStructure.USART_StopBits = USART_StopBits_1;

USART_InitStructure.USART_Parity = USART_Parity_No ;

USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;

USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;

USART_Init(USART1, &USART_InitStructure);


USART_Cmd(USART1, ENABLE);


NVIC_InitStructure.NVIC_IRQChannel = USART1_IRQn;

NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 12;

NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;

NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;

NVIC_Init(&NVIC_InitStructure);

}


void
USART1_IRQHandler(
void
)

{

u8 Ch = 1;

long
int
xHigherPriorityTaskWoken = pdFALSE;


if
(USART_GetITStatus(USART1, USART_IT_TXE) != RESET) {

if
(TXPtr < TXLen) {

USART_SendData(USART1,TXBuff[TXPtr++]);

}

else
{

TXPtr = 0;

TXLen = 0;

TXBuff = NULL;

USART_ITConfig(USART1, USART_IT_TXE, DISABLE);


xQueueSendFromISR(Queue_TXComplete, &Ch, &xHigherPriorityTaskWoken);

}

USART_ClearITPendingBit(USART1, USART_IT_TXE);

}


portEND_SWITCHING_ISR(xHigherPriorityTaskWoken);

}

USART3 Initialization and IRQ Handler:

void
XBee_Init(
void
)

{

GPIO_InitTypeDef GPIO_InitStructure;

USART_InitTypeDef USART_InitStructure;

NVIC_InitTypeDef NVIC_InitStructure;


vSemaphoreCreateBinary(WriteLock);

vSemaphoreCreateBinary(ReadLock);


Queue_TXComplete = xQueueCreate(1, 
sizeof
(u8));

Queue_RXChar = xQueueCreate(64, 
sizeof
(u8));

Queue_XBeeOK = xQueueCreate(1, 
sizeof
(u8));


ClearRXBuffer();


RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART3, ENABLE);

RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB, ENABLE);


GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;

GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;

GPIO_Init(GPIOB, &GPIO_InitStructure);


GPIO_InitStructure.GPIO_Pin = GPIO_Pin_11;

GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;

GPIO_Init(GPIOB, &GPIO_InitStructure);


USART_DeInit(USART3);

USART_InitStructure.USART_BaudRate = 9600;

USART_InitStructure.USART_WordLength = USART_WordLength_8b;

USART_InitStructure.USART_StopBits = USART_StopBits_1;

USART_InitStructure.USART_Parity = USART_Parity_No ;

USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;

USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;

USART_Init(USART3, &USART_InitStructure);

USART_Cmd(USART3, ENABLE);


USART_ITConfig(USART3, USART_IT_RXNE, ENABLE);


NVIC_InitStructure.NVIC_IRQChannel = USART3_IRQn;

NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 12;

NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;

NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;

NVIC_Init(&NVIC_InitStructure);


while
(USART_GetFlagStatus(USART3, USART_FLAG_RXNE) != RESET){

USART_ReceiveData(USART3);

}


xTaskCreate( Task_USART_RX, ( signed portCHAR * ) 
''Task_USART_RX''
, 200, NULL, 3 , NULL );

}


void
USART3_IRQHandler(
void
)

{

u8 Ch = 1;

long
int
xHigherPriorityTaskWoken = pdFALSE;

u8 Byte;


if
(USART_GetITStatus(USART3, USART_IT_TXE) != RESET) {

if
(TXPtr < TXLen) {

USART_SendData(USART3,TXBuff[TXPtr++]);

}

else
{

TXPtr = 0;

TXLen = 0;

TXBuff = NULL;

USART_ITConfig(USART3, USART_IT_TXE, DISABLE);


Ch = 1;

xQueueSendFromISR(Queue_TXComplete, &Ch, &xHigherPriorityTaskWoken);

}

USART_ClearITPendingBit(USART3, USART_IT_TXE);

}


if
(USART_GetITStatus(USART3, USART_IT_RXNE) != RESET){


Byte = USART_ReceiveData(USART3);

xQueueSendFromISR(Queue_RXChar, &Byte, &xHigherPriorityTaskWoken);

USART_ClearITPendingBit(USART3, USART_IT_RXNE);

}


portEND_SWITCHING_ISR(xHigherPriorityTaskWoken);

}

Thanks for any replies.

[Tesla DeLorean]

Posted on April 21, 2013 at 20:35

Suggest you test outside the clutter of the RTOS.

No need to explicitly clear the interrupt source if you Send/Receive Data.

[ondrej]

Posted on April 21, 2013 at 22:09

Hello clive1, 

thanks for your reply.I tried to run USART code outside of RTOS. Definitely i dont have any other ideas. Now it doesnt matter if USART1 was used or not. On USART3 RX pin signal looks like its permanently pull-upped. EDIT: Code optimizations are off. I tried to use different versions of code sourcery toolchain. Also i tried to combine USART1 & USART2 and USART2&USART3. Everytime with the same result.STDPeriphLib v3.5.0EDIT2: I forgot to say when USART3 code did not run within RTOS. IT RXNE was never fired. This is image of USART3 RX Pin - Without RTOS. If code run within RTOS and USART1 TX was called, USART3 RX Pin looks same like image above. If USART1 TX not called, signal looks normal.

[Tesla DeLorean]

Posted on April 22, 2013 at 01:09

Doesn't look like a valid signal, hardly surprising RXNE is not asserting.

[ondrej]

Posted on April 22, 2013 at 08:34

Of course it isn't. And I know that this signal is a reason why RXNE was never asserted. But how did i say before, if i dont send any data over USART1, USART3 works great. 

Thanks for your time Clive1.USART3 RX:

[Tesla DeLorean]

Posted on April 22, 2013 at 13:14

Ok, then perhaps we should be looking at your hardware and not the software. Suggest you describe the chip and board you're using, ideally with a schematic.

It could be related to software you haven't listed. You could simplify the implementation to the minimal code to demonstrate the failure, and provide a complete example.