Re: [Amforth] measuring time

[Robert E. <epp...@so...>]

Exploring amforth on my arduino uno is a bit difficult without
a working upload tool. I help myself with a simple bash script
which just waits after characters and newlines and works often
(but not always) for short single files and is  s l o o o o w ...


But here we go:
Whats wrong with the following simple test code:

\ ################################################################
marker _TIMER0_

variable ticks

: tim0isr ( -- )   1 ticks +! ;		\ timer0 ISR

: tim0ini ( -- )			\ initialize timer0
    0 ticks !
    0 TCNT0 c!	\ clear counter
    0 TCCR0A c!	\ normal mode
    4 TCCR0B c!	\ internal clock /256	\ hangs system, had to re-flash amforth
\ some variants:
\    3 TCCR0B c!	\ internal clock, prescaler set to 64	\ does NOT tick
\    TCCR0B c@ &fff8 and 3 or TCCR0B c! \ internal clock /64 	\ same
\    5 TCCR0B c!			\ internal clock /1024	\ reset?
    ['] tim0isr TIMER0_OVFAddr int!
\	['] noop TIMER0_OVFAddr int!	\ just a test
;

: +tim0int ( -- )   1 TIMSK0 c! ;	\ enable interrupt

: -tim0int ( -- )   0 TIMSK0 c! ;	\ disable interrupt

: tim0start ( -- )  tim0ini +tim0int ;

\ ################################################################

The result on my arduino uno is quite inconsistent, but mostly I see:

3 TCCR0B c!
does not hang the system, but does not tick either.

4 TCCR0B c!
hangs system, had to re-flash amforth
often also takes my /dev/ttyACM0 down and I have to reboot linux
(which looks to me like a linux kernel issue).

5 TCCR0B c!
reset?
The system starts to print the boot message interruptet by some
bytes of garbage and endlessly repeats that.


Confused,
Robert