Jan,
> I think some where in amForth TCNT1 is overwritten!
Indeed. Every time timer1 overflows.
> When I change some of the preload value by hand no change is seeing.
> Frequency is staying at 15,2 Hz.
Yes. You are seeing a frequency of
16000000 divided by 8 (for the prescaler)
divided by 65536 (for each rollover of the timer1)
divided by 2 (for the LED toggle)
which gives a theoretical 15.3Hz , close to your observed value.
Are you looking to generate something for multiplexing a display?
There might be an easier way, if that is the case.
Best wishes,
Tristan
On 02Nov18 20:09, Jan Kromhout wrote:
> Hi,
>
> I have taken the TIMER_1 example, and make some small change.
> Instead of the timer1.tick I toggle pin-7 of the Arduino.
> With the values as in the listing I measure a frequency of 15,2 Hz with my
> scoop.
>
> When I change some of the preload value by hand no change is seeing.
> Frequency is staying at 15,2 Hz.
>
> When I print the value of TCNT1 after setting, and compare this one after
> timer1.start there is a difference
>
> First value = 63536 and the Second value = 31033.
>
> I think some where in amForth TCNT1 is overwritten!
>
> Please can you take a look.
>
> I included my program.
>
> Cheers,
>
> Jan
>
> \ TIMER1_interrupt
>
> marker --timer1_interrupt--
>
> PORTD 7 portpin: PD7
> PD7 pin_output
>
> &26 constant TIMER1_OVFAddr
>
> : togglePD7
> PD7 pin_high? if PD7 low else PD7 high then
> ;
>
> : timer1.isr
> \ toggle output PD7
> togglePD7
> ;
>
> \ preload for overflow interrupt every 1 ms
> \ preload = 65536 - (f_cpu / (prescaler * 1000))
>
> : timer1.preload
> f_cpu #1000 um/mod nip 8 / negate \ <===== if i change the value #1000
> notting is change
> ;
>
> : timer1.init ( -- )
> timer1.preload TCNT1 !
> TCNT1 @ u. cr \ <=============== print value of TCNT1 ===========
> ['] timer1.isr TIMER1_OVFAddr int!
> ;
>
> : timer1.start
> -int
> timer1.init
> %00000010 TCCR1B c! \ prescaler 8
> %00000001 TIMSK1 c! \ enable overflow interrupt
> +int
> ;
>
> : timer1.stop
> %00000000 TCCR1B c! \ stop timer
> %00000000 TIMSK1 c! \ stop interrupt
> ;
>
>
>
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