Re: [Amforth] AVR8 watchdog (reset and interrupt) atmega328p

[MIchael Kalus]

Müsste es dann nicht c!wd heißen?
Michael

2017-05-07 15:42 GMT+02:00 Matthias Trute :

> Hi Tristan,
>
> I've put your code online, revision 2252 contains the new
> file. There is only one change: I renamed the wd! into !wdc.
> It tells "store to watchdog control" and follows the more
> or less informal convention that ! and @ can be preceeded
> with size information and followed by location information.
> Just like c!e or @i. Hope that's ok for you.
>
> http://amforth.sourceforge.net/TG/recipes/Watchdog.html
>
> Thank you
> Matthias
> 
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Re: [Amforth] AVR8 watchdog (reset and interrupt) atmega328p

[Matthias Trute]

Hi Tristan,

I've put your code online, revision 2252 contains the new
file. There is only one change: I renamed the wd! into !wdc.
It tells "store to watchdog control" and follows the more
or less informal convention that ! and @ can be preceeded
with size information and followed by location information.
Just like c!e or @i. Hope that's ok for you.

http://amforth.sourceforge.net/TG/recipes/Watchdog.html

Thank you
Matthias
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Re: [Amforth] AVR8 watchdog (reset and interrupt) atmega328p

[Tristan Williams]

Hello Matthias,

> I'll look at them in the next few days. Since we've just discovered
> some interrupt related bugs so maybe I'll ask you to do some
> tests with the code I will checkin. Is this ok for you? 

Absolutely fine.

Tristan



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Re: [Amforth] AVR8 watchdog (reset and interrupt) atmega328p

[Tristan Williams]

Hello Matthias,

> IIRC only the "disable watchdog" sequence is timing critical (the
> 4 cpu cycles you mention). All other tasks can be performed at
> lower speed, so a forth implementation should be fine.

My atmega328p seems to require any change to WDTCSR to be completed
within 4 cycles (I have tried), so I do not think a pure forth
solution (excluding using assembler.frt) is possible.
 
> It would be a great contribution for the cookbook. Esp if it works with
> Forth code.

This made me think that writing 4 or 5 assembler words was not the
best way. Instead, have one assembler word wd! to perform the timed
write to WDTCSR and then have forth words for -wdt +wdt -wdi +wdi
wd.delay! I think this was the approach (one assembler word) used in
2013 with assembler.frt so had I read it better I might have got there
more quickly.

https://sourceforge.net/p/amforth/mailman/message/31512894/

Included below are three files wdwrite.asm, wd.forth and
wd-example.forth. Regarding wdwrite.asm, it is the first time I have
used assembler since 1985. wd.forth has more comments than code and
wd-example.forth may not be up to cookbook standards, though it has a
number of examples. Many of these examples intentionally result in the
avr microprocessor being reset on the watchdog timeout...

; wdwrite.asm
; 
; 
VE_WDWRITE:
.dw $ff03
.db "wd!"
.dw VE_HEAD
.set VE_HEAD = VE_WDWRITE
XT_WDWRITE:
.dw PFA_WDWRITE
PFA_WDWRITE:

 in temp1,SREG
 push temp1

 mov temp0, tosl

 cli
 ; Reset Watchdog Timer
 wdr
 ; Clear WDRF in MCUSR
 in temp1, MCUSR
 andi temp1, (0xff & (0<

Re: [Amforth] AVR8 watchdog (reset and interrupt) atmega328p

[Matthias Trute]

Am Donnerstag, den 20.04.2017, 09:04 +0100 schrieb Tristan Williams:
> AVR8 watchdog (reset and interrupt) atmega328p
> 
> I wanted to use the 128 kHz watchdog oscillator as an additional
> timer.

The watchdog creates a full reset cycle, that means that the full
startup sequence is performed. Your turnkey action should take
care of this (register r10 holds the reset cause).

> 
> In the source tree there is an assembler word -wdt (no-wdt.asm),
> which
> writes $0 to WDTCSR (using the prescribed sequence), but I couldn't
> find something like a "+wdt". This may well be because I did not look
> hard enough, so my apologies if it was there all along.

IIRC only the "disable watchdog" sequence is timing critical (the
4 cpu cycles you mention). All other tasks can be performed at
lower speed, so a forth implementation should be fine.

> 
> Using -wdt as a template I have written four companion assembler
> words
> and a slightly modified version of -wdt (to leave the existing
> prescaler and WDIE bit unmodified).
> 
> +wdt ( -- )set WDE (System Reset Mode)   
> -wdt ( -- )unset WDE (leaves prescaler)  
> +wdi ( -- )set WDIE (Interrupt mode) 
> -wdi ( -- )unset WDIE (leaves prescaler) 
> wd.delay! ( n -- ) set prescaler , unset WDE and unset WDIE 
> 
> where n is the 4 bits representing the prescaler. 
> 
> With the 4 cycle write requirement dealt with by (optional at build
> time) built in words the 128kHz timer is accessible and adds a
> lot. Could similar words be added to AmForth or is this too
> device/application specific?

It would be a great contribution for the cookbook. Esp if it works with
Forth code.

Good work
Matthias
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[Amforth] AVR8 watchdog (reset and interrupt) atmega328p

[Tristan Williams]

AVR8 watchdog (reset and interrupt) atmega328p

I wanted to use the 128 kHz watchdog oscillator as an additional
timer.  I saw that AVR8 watchdog timer and reset was addressed on the
mailing list in late 2013 using assembler.frt 

In the source tree there is an assembler word -wdt (no-wdt.asm), which
writes $0 to WDTCSR (using the prescribed sequence), but I couldn't
find something like a "+wdt". This may well be because I did not look
hard enough, so my apologies if it was there all along.

Using -wdt as a template I have written four companion assembler words
and a slightly modified version of -wdt (to leave the existing
prescaler and WDIE bit unmodified).

+wdt ( -- )set WDE (System Reset Mode)   
-wdt ( -- )unset WDE (leaves prescaler)  
+wdi ( -- )set WDIE (Interrupt mode) 
-wdi ( -- )unset WDIE (leaves prescaler) 
wd.delay! ( n -- ) set prescaler , unset WDE and unset WDIE 

where n is the 4 bits representing the prescaler. 

With the 4 cycle write requirement dealt with by (optional at build
time) built in words the 128kHz timer is accessible and adds a
lot. Could similar words be added to AmForth or is this too
device/application specific?






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