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Three interrupt only blocks INT_RDA

 
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Audi80



Joined: 07 Sep 2007
Posts: 41

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Three interrupt only blocks INT_RDA
PostPosted: Wed Sep 22, 2010 5:16 am     Reply with quote

Hi there i´ve developed a project using three interrupts:

1 - INT_RDA
2 - INT_EXT1 HIGH
3 - INT_EXT2 HIGH

My problem now is the following:

This project is an IO controller that is polled by a master every 100ms and sends the IO status. The INT_ETXs are used to increment an int like this:

Code:

#INT_EXT1 HIGH
void pulseCounter1(){
    ++pulses;
}


And the INT_RDA does the following:


Code:

#INT_RDA
void communications(){       
    output_high(RX_STATUS);
    buffer[ptr++]=getc();
    if(ptr>=5){       
        if(buffer[ptr-5]==ENQ){
            receiveMsg(buffer);
            clearBuffer();
        }
        else if(buffer[ptr-2]==ETX){
            receiveMsg(buffer);
            clearBuffer();
        }
        else if(ptr==MAX_BUFFER_LEN) {
            clearBuffer();
        }
    }   
    output_low(RX_STATUS);
}


What happens is this, my controller can work 10h hours or just 10min and stops working because it seems that the INT_RDA without any explanation stops working because the led stops blinking.

The only answer i can find for this is if the INT_EXT and INT_RDA occurs exactly at the same time... Shocked

Does anyone know whats the result of it?

Thanks in advance
bkamen



Joined: 07 Jan 2004
Posts: 1615
Location: Central Illinois, USA

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PostPosted: Wed Sep 22, 2010 8:57 am     Reply with quote

Need a little more info.

What's the declared SIZE of buffer?
What speed is the RS232 running at?

What PIC, what version of CCS compiler?

It shouldn't be a problem that the IRQ's happen at the same time. The handler takes care of this and services them sequentially anyway. (you can control this with #priority pre-processor command)

-Ben
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Dazed and confused? I don't think so. Just "plain lost" will do. :D
Gabriel



Joined: 03 Aug 2009
Posts: 1067
Location: Panama

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PostPosted: Wed Sep 22, 2010 9:12 am     Reply with quote

IMO, your ISR is waaaayy to long..

better to set a flag and then do all the stuff you got in there out of the ISR.

just my 2 cents...


Gabriel
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CCS PCM 5.078 & CCS PCH 5.093
bkamen



Joined: 07 Jan 2004
Posts: 1615
Location: Central Illinois, USA

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PostPosted: Wed Sep 22, 2010 9:19 am     Reply with quote

Gabriel wrote:
IMO, your ISR is waaaayy to long..

better to set a flag and then do all the stuff you got in there out of the ISR.


I was going to ask that next.

What do

receiveMsg(buffer);
clearBuffer();


do?

I'm guessing it's too much and what's happening is the UART is overflowing.

You want to get in, get your char, get out.

Build a state machine that detects the ETX or end of buffer and then stop and wait for it to be processed (external flag of some sort).

That's what I do with my GPS routines and they work fine.

All the reception is done INSIDE the ISR.
All the "processing" is done outside the ISR.

-Ben
_________________
Dazed and confused? I don't think so. Just "plain lost" will do. :D
Audi80



Joined: 07 Sep 2007
Posts: 41

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PostPosted: Wed Sep 22, 2010 11:24 am     Reply with quote

It seems I found the problem. My receiveMsg(buffer) at some point was writing stuff to the eeprom. And when I removed it the problem seemed to stop. It could be that...

If the problems persists I will post more questions Laughing

Thanks for your help....
bkamen



Joined: 07 Jan 2004
Posts: 1615
Location: Central Illinois, USA

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PostPosted: Wed Sep 22, 2010 1:35 pm     Reply with quote

You're taking too much time.

I'm guessing now your ISR isn't being serviced fast enough for incoming data and the result is a buffer overflow.

Like we said, keep your ISR to ONLY collecting chars to the buffer.

When the buffer is full or a packet is received, set a flag for the main loop to process it.

-Ben
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Dazed and confused? I don't think so. Just "plain lost" will do. :D
Ttelmah



Joined: 11 Mar 2010
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PostPosted: Wed Sep 22, 2010 2:57 pm     Reply with quote

One byte to EEPROM, takes between 2*, and 4* the character time at 9600bps(depending on the chip), so 'yes', a killer for serial comms....
Also, hopefully, this code is not called at all frequently, or the EEPROM life limitations may need to be considered.....

Best Wishes
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