Subject:
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Re: [long] Interrupt programming, buggy code
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Newsgroups:
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lugnet.robotics.rcx
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Date:
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Tue, 2 Mar 2004 17:51:14 GMT
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Viewed:
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3332 times
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In lugnet.robotics.rcx, Benjamin Sigonneau wrote:
> Hi all,
>
> I am currently programming the Lego RCX at low-level (plain C) using the
> GCC cross-compiler for Hitachi H8/300 and Kekoa Proudfoot's LibRCX. In
> fact, I'm designing exercises for students that learn micro-controller
> programming. Therefore, I don't even use the ROM routines (except those
> that deals with the lcd display).
All I can give you is guesses. There are pleny of gurus here who will know the
answer.
Do you know if the display_debug() routine or any of the things it uses depends
on the interrupts you are taking over? If default interrupt handler provides
facilities for display_debug(), and your handler does not provide those
facilities, maybe you hang?
>
> I managed to deal with motors and touch sensors using both the Hitachi
> Hardware Manual and Kekoa Proudfoot's "RCX Internals".
>
> I know want to program the H8/300 interrupts. I've managed to define an
> OCIA handler, but I'm afraid I've missed something since I can't get it
> to work right. This handler only increments a global and then displays
> its value on the LCD. That should be easy, but... When I run my program,
> the LCD displays 0, then 1, then 2, then 3, then... Then the RCX hangs,
> and I can't get anything from it. I have to remove the batteries and put
> them in again to "reboot" the crashed RCX.
Can we assume that interrupts are disable while in ocia_handler()? An infinite
number of interrupts would cause this to happen. Is there some other interrupt
source that you are enabling when you unmask, and it takes a while to fire?
Once it fires, it never stops because the interrupt handler(s) don't clear it?
>
> I just don't see what I'm doing wrong, so I'm asking if anybody has an
> idea. In case such gurus lie around here, I post my C code below.
I'm very interested in seeing your final code. I've used Kekoa's framework too
and it is pretty handy.
Kevin
>
> Thanks.
>
>
> /* My buggy code */
>
> int count;
>
> #define mask_it() asm ("orc #0x80, ccr");
> #define unmask_it() asm ("andc #0x7f, ccr");
>
> #define OCIA_HANDLER *( (volatile word *) 0xfda2)
>
> void ocia_handler(void) __attribute__ ((interrupt_handler));
> void ocia_handler(void) {
> FRT_TCSR &= ~bit3; /* clear output compare flag A */
> count++;
> debug_value(count);
> }
>
> int main (void) {
>
> count = 0;
>
> /* debug_value is just a call to ROM routine at 0x1ff2
> * that displays an integer */
> debug_value(count);
>
> OCIA_HANDLER = (word)ocia_handler; /* install OCIA handler */
>
> /* Timer clock selection: use div 32 clock */
> FRT_TCR |= bit1; /* CSK1 <- 1 */
> FRT_TCR &= ~bit0; /* CSK0 <- 0 */
>
> FRT_TCSR = bit0; /* Clear FRT on compare-match A */
> FRT_TOCR &= ~bit4; /* Compare timer to OCRA */
> FRT_OCRA = 50000; /* Interrupt every 100 ms */
> FRT_FRC = 0; /* Clear free running timer */
> FRT_TCSR &= ~bit3; /* Clear output compare flag A */
>
> /* Enable OCIA - see p. 117
> * ie an interrupt is generated when FRT == OCRA
> */
> FRT_TIER |= bit3;
>
> /* Unmask interrupts */
> unmask_it();
>
> while (!prgm_pressed()) {
> /* Wait for "pgrm"button to be pressed */
> }
>
> return 0;
> }
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Message is in Reply To:
 | | [long] Interrupt programming, buggy code
|
| Hi all, I am currently programming the Lego RCX at low-level (plain C) using the GCC cross-compiler for Hitachi H8/300 and Kekoa Proudfoot's LibRCX. In fact, I'm designing exercises for students that learn micro-controller programming. Therefore, I (...) (21 years ago, 2-Mar-04, to lugnet.robotics.rcx)
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