[net.micro.amiga] In quest of a MilliSecond Stopwatch

fdfishman@watcgl.UUCP (Flynn D. Fishman) (06/25/86)

Well in quest of a 1 millisecond stopwatch before going to hardware, we have
decided to give the 8520(-B) chip a chance

I am getting no where with it.  I can not seem to get the timer to do anything.

What I am doing is.  
  I am setting up variables like so
     SHORT *timer_low_A (= 0xbfd400)
     SHORT *control_register_A (= 0xbfde000
     *control_register_A = 0x71
     print *timer_low_A
(note that the numbers in brackets are assigned at another point in the program)

The problem arises in that timer_low_A does not change at all.
I have also tried playing around with PRA, and DDRA (Is that a typo in the
hardware manual, I am assuming that DDRA = 0xbfd200 and DDRB = 0xbfd300)
but regardless of what I do timer_low_A does not change.

I would like to be able to eventually have timer B count down, and cause A to
decrement on B's underflow, but if I can not even get A (or B for that matter)
moving I am stuck.

If any one can help me with this problem or present a better way to get a
1 millesecond grain timer I would really appreciate it.  I do not want use
hardware, because then it would be harder to run the experiment
simultaneously and publish our algorithms.

(A recap of the problem for those who forgot or are new)
I need to be able to calculate the time from when a stimulus is displayed
on the screen to the point in time when the user presses a mouse button.

(I am using Manx C on a 512k Dual Drive System)

    Thanks you very much
-- 

      FDFISHMAN (Flynn D. Fishman)

UUCP  :	...!{decvax|ihnp4|clyde|allegra|utzoo}!watmath!watcgl!fdfishman   
ARPA  :	fdfishman%watcgl%waterloo.csnet@csnet-relay.arpa 
CSNET :	fdfishman%watcgl@waterloo.csnet

grr@cbmvax.cbm.UUCP (George Robbins) (06/27/86)

In article <792@watcgl.UUCP> fdfishman@watcgl.UUCP (Flynn D. Fishman) writes:
>Well in quest of a 1 millisecond stopwatch before going to hardware, we have
>decided to give the 8520(-B) chip a chance
>
>I am getting no where with it.  I can not seem to get the timer to do anything.

You did notice that one 8520 is on the high order data lines, and the other
is on the low order lines?  I guess this is so you can munch both at once with
word accesses, but it's kind of confusing...

-- 
George Robbins - now working with,	uucp: {ihnp4|seismo|caip}!cbmvax!grr
but no way officially representing	arpa: cbmvax!grr@seismo.css.GOV
Commodore, Engineering Department	fone: 215-431-9255 (only by moonlite)

robinson@shadow.Berkeley.EDU (Michael Robinson) (07/03/86)

[I ain't afraid of no bugs]

>If any one can help me with this problem or present a better way to get a
>1 millesecond grain timer I would really appreciate it.

Has anyone ever tried using the sound chips for a clock?  The way I read the 
hardware reference, you should be able to set up a short (one byte) waveform,
set the sample time, and get an interupt.  The interupt handler would increment
the timer value, reset the sound DMA, and return.  Then, <sample time> later,
you would get another interupt and the process would repeat.

Am I way off base?