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Discussion Groups | 68HC12 | Re: Re: D64 COP: the saga continues
Join our technical discussions about Freescale Microcontrollers: M68HC12. (Freescale Semiconductor is a Subsidiary of Motorola).
Re: Re: D64 COP: the saga continues - Edward Karpicz - Mar 28 6:22:11 2008
WadeA & RebeccaM Smith wrote:
> the reset chip (brownout detector) is MC34064D-5R2, if that helps.
OK, good old MC34064
>
> I have put BGND instructions at several of the reset vector locations
> where it is expecting a JMP instruction (0x06 IIRC). And the I run
> NoICE. No dice.
BGND instruction don't help to stop part in normal mode. These work only in
special mode. In normal mode BGND causes a jump to and return from BDM
firmware, which takes >60 bus cycles (CPU12 manual doesn't tell everything).
And in order to get into special mode on COP reset, BKGD pin should be
pulled low. But with BKGD pin permanently pulled low you can't start your
code, it will loop in BDM firmware. Do you have some unused buttons? If you
have, then maybe power up with BKGD pulled high, then start looping waiting
for button, then pull BKGD low and continue? I don't know if this will help
catching your BGND.
> If COP is running Reset... reset... reset... reset...
> If COP is running, even RSBCK doesnt help. (CUSS!)
RSBCK? It makes sense only for BDM debug sessions. I completely lost track
of what you are doing and asking for.
Regards
Edward
> If COP is not running, no problem. Everybody is happy (except Mr EE).
>
> wade
>> ----- Original Message -----
>> From: "Edward Karpicz"
>> To: <6...@yahoogroups.com>
>> Sent: Wednesday, March 26, 2008 10:24 AM
>> Subject: Re: [68HC12] Re: D64 COP: the saga continues
>> > WadeA & RebeccaM Smith wrote:
>> >
>> >> --- In 6...@yahoogroups.com, Petrescu wrote:
>> >>>
>> >>> Hi Wade,
>> >>> Can you tell us how did you configured your hardware reset circuit
>> >>> for the microprocessor?
>> >>> Regards,
>> >>> Ioan
>> >>
>> >> The hardware reset is rather boring -- nothing useful or exciting
>> >> there. A button connectec between the /reset pin (complete with a
>> >> pull-up resistor of 4K7 to +5V) and ground. Oh, and some sort of
>> >> brownout/powerup management chip in there too, but that's not very
>> >> exciting either.
>> >
>> > It isn't boring, it's important. There are 1) reset chips that
> sense Vdd
>> > circuit, there are 2) reset chips with push-pull output and there
> are 3)
>> > reset chips that sense /RESET circuit. /RESET pin is bidirectional so
>> > number
>> > 2 is incompatible without extra parts.
>> > Number three makes HC12 unable to use COP and CME vectors, all resets
>> > default to vector at FFFE. When COP reset happens, HC12 pulls
> /RESET low
>> > for
>> > a moment; brownout detector sees it and generates it's own reset
> pulse...
>> >
>> > Edward
>
> ------------------------------------
(You need to be a member of 68hc12 -- send a blank email to 68hc12-subscribe@yahoogroups.com )
> the reset chip (brownout detector) is MC34064D-5R2, if that helps.
OK, good old MC34064
>
> I have put BGND instructions at several of the reset vector locations
> where it is expecting a JMP instruction (0x06 IIRC). And the I run
> NoICE. No dice.
BGND instruction don't help to stop part in normal mode. These work only in
special mode. In normal mode BGND causes a jump to and return from BDM
firmware, which takes >60 bus cycles (CPU12 manual doesn't tell everything).
And in order to get into special mode on COP reset, BKGD pin should be
pulled low. But with BKGD pin permanently pulled low you can't start your
code, it will loop in BDM firmware. Do you have some unused buttons? If you
have, then maybe power up with BKGD pulled high, then start looping waiting
for button, then pull BKGD low and continue? I don't know if this will help
catching your BGND.
> If COP is running Reset... reset... reset... reset...
> If COP is running, even RSBCK doesnt help. (CUSS!)
RSBCK? It makes sense only for BDM debug sessions. I completely lost track
of what you are doing and asking for.
Regards
Edward
> If COP is not running, no problem. Everybody is happy (except Mr EE).
>
> wade
>> ----- Original Message -----
>> From: "Edward Karpicz"
>> To: <6...@yahoogroups.com>
>> Sent: Wednesday, March 26, 2008 10:24 AM
>> Subject: Re: [68HC12] Re: D64 COP: the saga continues
>> > WadeA & RebeccaM Smith wrote:
>> >
>> >> --- In 6...@yahoogroups.com, Petrescu
>> >>>
>> >>> Hi Wade,
>> >>> Can you tell us how did you configured your hardware reset circuit
>> >>> for the microprocessor?
>> >>> Regards,
>> >>> Ioan
>> >>
>> >> The hardware reset is rather boring -- nothing useful or exciting
>> >> there. A button connectec between the /reset pin (complete with a
>> >> pull-up resistor of 4K7 to +5V) and ground. Oh, and some sort of
>> >> brownout/powerup management chip in there too, but that's not very
>> >> exciting either.
>> >
>> > It isn't boring, it's important. There are 1) reset chips that
> sense Vdd
>> > circuit, there are 2) reset chips with push-pull output and there
> are 3)
>> > reset chips that sense /RESET circuit. /RESET pin is bidirectional so
>> > number
>> > 2 is incompatible without extra parts.
>> > Number three makes HC12 unable to use COP and CME vectors, all resets
>> > default to vector at FFFE. When COP reset happens, HC12 pulls
> /RESET low
>> > for
>> > a moment; brownout detector sees it and generates it's own reset
> pulse...
>> >
>> > Edward
>
> ------------------------------------
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