Maybe I'm missing something obsious here...

Let's say the filling function is called CANPut(), and it fills a CAN 
message, activates the corresponding interrupt and return True if there 
was space for the message. I have a function CANSendMessage which does:

void CANSendMessage() {

    //fill the 100-byte buffer

    while (CANPut());
}

In the ISR I have:

if (can TX interrupt) {
    while (CANPut());
}

Until here am I correct ?

The compiler will give: CANPut() is called from different.... - 
reentrant code.

Lucian

YAP wrote:

>On 3/31/06, Lucian Copat <lucian.copat@audiotel.ro> wrote:
>  
>
>>I know that a message has at maximum 8 bytes in CAN, that's why I need
>>to develop my own higher layer protocol to fragment the data. But when
>>the interrupt is enabled, it doesn't activate if the buffer is empty,
>>but when the buffer becomes empty (after having sent a CAN message).
>>
>>In this way, I can only avoid reentrance by writing the same code twice
>>or by setting a flag in the interrupt.
>>
>>Lucian
>>    
>>
>
>
>I can't understand the problem here either if you use the method Gerhard
>suggest.
>
>1.) When you have data to send fill all free buffers. Enable interrupt.
>2.) When you get a frame sent interrupt fill data again if any to all free
>buffers.
>
>No need to rewrite code use a function call to fill the buffers. It will
>only be called by one process anyway and don't need to be reentrant.
>
>/Ake
>
>
>
>Gerhard Fiedler wrote:
>  
>
>>>Lucian Copat wrote:
>>>
>>>
>>>
>>>      
>>>
>>>>My question regards the E-CAN module in PIC18F4680. I have a routine
>>>>which loads a message (100 bytes max) into a temporary sending buffer.
>>>>
>>>>
>>>>        
>>>>
>>>You know that a single CAN message can only have 8 bytes payload, right?
>>>
>>>
>>>
>>>      
>>>
>>>>I would like that after loading this buffer, when I activate the TX
>>>>interrupts, the ISR to be called if there are some free buffers. E-CAN
>>>>module does generate an interrupt only when a buffer _becomes_ empty,
>>>>which means I should load it first. If I load it first and also in ISR,
>>>>I would have reentrant code. Is there any method to pass this problem ?
>>>>
>>>>
>>>>        
>>>>
>>>You would typically disable the TX interrupt in the ISR when it sees that
>>>there are no more bytes. Then, after initiating the next tx sequence, you
>>>reenable it. This way, there's no problem with reentrance.
>>>
>>>Gerhard
>>>
>>>
>>>
>>>      
>>>
>>--
>>*Lucian Copat
>>Software Team Leader
>>Audiotel Comlabs
>>E-mail: lucian.copat@audiotel.ro
>>Mobile: (+4)0722.729.658
>>Web: http://www.audiotel.ro*
>>--
>>http://www.piclist.com PIC/SX FAQ & list archive
>>View/change your membership options at
>>http://mailman.mit.edu/mailman/listinfo/piclist
>>
>>    
>>

-- 
*Lucian Copat
Software Team Leader
Audiotel Comlabs
E-mail: lucian.copat@audiotel.ro
Mobile: (+4)0722.729.658
Web: http://www.audiotel.ro*
-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist