CAN TX interrupt

[aloui]

Posted on May 17, 2009 at 14:26

CAN TX interrupt

[aloui]

Posted on May 17, 2011 at 13:11

Hello every body,

I have a trouble in getting CAN transmission interrupt to work.

How do i activate the interrupt?

I use this while initialising the NVIC:

NVIC_InitStructure.NVIC_IRQChannel = USB_HP_CAN_TX_IRQChannel;

NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;

NVIC_InitStructure.NVIC_IRQChannelSubPriority = 192;

NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;

NVIC_Init(&NVIC_InitStructure);

I am using FREERTOS so i need the priority to be higher than 191 in order to make some features work.

And each time i want to send data i put it in a queu and then activate the TX interrupt as follow

void CAN_Write(char* c)

{

char* d=c;

xSemaphoreTake(xCANTXSemaphore,( portTickType ) portMAX_DELAY);

while(*d!=0)

{

xQueueSend(xCANQueuTX, d++,( portTickType ) portMAX_DELAY);

}

CAN_ITConfig(CAN_IT_TME, ENABLE);//on active l'interruption d'ecriture

xSemaphoreGive(xCANTXSemaphore);

}

Then in the IRQ i do this:

void ISR_CANTX()

{

CanTxMsg TxMessage;

portBASE_TYPE xHigherPriorityTaskWoken=pdFALSE ;

TxMessage.StdId=0x11;

TxMessage.RTR=CAN_RTR_DATA;

TxMessage.IDE=CAN_ID_STD;

TxMessage.DLC=2;

//Si il y a encore quoi envoyer on envoi

if(xQueueReceiveFromISR( xRS232QueuTX, &( TxMessage.Data[0] ),&xHigherPriorityTaskWoken))

{

CAN_Transmit(&TxMessage);

}

else//sinon on desactive cette interruption

{

CAN_ITConfig(CAN_IT_TME,DISABLE);

}

CAN_ClearITPendingBit(CAN_IT_TME);

portEND_SWITCHING_ISR( xHigherPriorityTaskWoken );

}

I chack the queu, if there is something to send i send it else i disactivate the interrupt.

I have initialised the interrupts vector to make this routine the one called when an interrupt occurs on USB_HP_CAN_TX_IRQChannel.

Did i miss something, and am i right to use this IRQChannel and this interrupt: CAN_ITConfig(CAN_IT_TME, ENABLE); ?

Thanks

[ This message was edited by: aloui.seifeddine on 12-05-2009 22:59 ]

[amin2]

Posted on May 17, 2011 at 13:12

Hi Seif,

The TME interrupt is connected to 3 Flags (RQCP2,RQCP1,RQCP0)

the description of RQCPx flag is :

Request Completed for Mailbox x , This bit is set by hardware to signal that the last request for mailbox x has been completed. The request could be a transmit or an abort request. This bit is cleared by software writing 1.

The TME interrupt is an indicator that the Transmission is done (or aborded). ;)

Amin

[aloui]

Posted on May 17, 2011 at 13:12

In fact, i think there is a Bug in the STM32. It is written that TME is Transmit Mailbox Empty, but i found that this interrupt occurs when the CAN TX transmission is done!!!