Sebastian Davalle

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10 years, 1 month ago.

Buffered CAN Messages during Interrupt context

According to the LPC17xx_User_Manual each CAN module has two receive buffers. That means that while you are reading one message, another can be received. What happens when a RX_IRQ is been handled? I've tried to read all available messages from CAN, but the maximum number of messages read is two. Shall I think that during interrupt context there are not new messages buffered?

read can messages

void CANInterruptCallBack()
{
    NVIC_DisableIRQ(CAN_IRQn);

    _status = _can.read(_receivedMessage);
    while (_status == 1)
    {
        _buffer.queue(_receivedMessage);
        _status = _can.read(_receivedMessage);
    }

    NVIC_EnableIRQ(CAN_IRQn);
}

Thank in advance

My mistake, during interrupt, I can only read one message from CAN. I've been reading the User Manual and it says that an interrupt is triggered when an message is copied to the reception buffer.

posted by Sebastian Davalle 12 Mar 2014

1 Answer

Erik -
10 years, 1 month ago.

Handling your RX interrupt should be done in a very short time. Using that code it can at max read its two receive buffers, but then the read will return 0, and the function ends long before the third message arrives.

Btw disabling the interrupt isn't required, an interrupt cannot interrupt itself.