Timing with the BS2
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I am working on a device that measures the deacceleration of balls as
they pass through light gates but I'm having a problem with the
timing
using the BS2. It times in 2us units so the maximum length of time is
0.131s. If anybody knows how I can time for longer periods to ms
accuracy please let me know. I tried using a loop with the pause
command for 1 ms but it then takes 0.3 ms to read the pause
instruction and 0.3 ms to read the instruction after it so it's no
good. Any help would be appreciated.
Andy
they pass through light gates but I'm having a problem with the
timing
using the BS2. It times in 2us units so the maximum length of time is
0.131s. If anybody knows how I can time for longer periods to ms
accuracy please let me know. I tried using a loop with the pause
command for 1 ms but it then takes 0.3 ms to read the pause
instruction and 0.3 ms to read the instruction after it so it's no
good. Any help would be appreciated.
Andy
Comments
between accuracy and duration. The basic measurement is 16 bits of 5uS.
However, you can divide that by 2, 4, 8, 16, 32, 64, 128, or 256 (that's
10uS to 1.28mS). You use SHIFTIN and SHIFTOUT to talk to the PAK and it
measure 8 channels at once.
Regards,
Al Williams
AWC
http://www.al-williams.com/awce/pak7.htm
>
Original Message
> From: Andy Schwarz [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=dDOk2nJtlUVhuYYD1byNwhp1E-awKq4t_fglo-ad0tocTAgwAE33B5KN8ZBFpaXeU5GL7UckfzwoMTDHnxzXbI9u991G140p-g]phyaks@p...[/url
> Sent: Tuesday, October 10, 2000 10:21 AM
> To: basicstamps@egroups.com
> Subject: [noparse][[/noparse]basicstamps] Timing with the BS2
>
>
> I am working on a device that measures the deacceleration of balls as
> they pass through light gates but I'm having a problem with the
> timing
> using the BS2. It times in 2us units so the maximum length of time is
> 0.131s. If anybody knows how I can time for longer periods to ms
> accuracy please let me know. I tried using a loop with the pause
> command for 1 ms but it then takes 0.3 ms to read the pause
> instruction and 0.3 ms to read the instruction after it so it's no
> good. Any help would be appreciated.
>
> Andy
>
>
>
Check out http://www.phanderson.com/timer_1_2.html.
Cheers,
Steve
>they pass through light gates but I'm having a problem with the
>timing
>using the BS2. It times in 2us units so the maximum length of time is
>0.131s. If anybody knows how I can time for longer periods to ms
>accuracy please let me know. I tried using a loop with the pause
>command for 1 ms but it then takes 0.3 ms to read the pause
>instruction and 0.3 ms to read the instruction after it so it's no
>good. Any help would be appreciated.
Hi Andy,
A tight loop can count the time P0 stays high in units of .713 milliseconds
on a BS2:
x var word
timer:
x=0
timer0: ' wait here until P0 goes high
branch in0,[noparse][[/noparse]wait2start]
timer1: ' 1426 loops per second, 7.013E-4 seconds per loop
x=x+1
if in0 then timer1 ' count until in0 goes low
debug dec x**45960," milliseconds",cr ' ** converts to millisecs.
goto timer
True, there is uncertainty in the result due to the loop processing time.
Here are links to external timer chips made for the stamp:
http://home.earthlink.net/~parkiss/tm1summ.txt
http://www.phanderson.com/timer_1_2.html
http://www.al-williams.com/awce/pak7.htm
I hope that helps
-- Tracy Allen
electronically monitored ecosystems
http://www.emesystems.com
Andy
It is not possible to get faster time counting with a stamp that I know of.
Try using an external counter, timebase generator, and a shift register to
move data into the stamp from the counter.
Chuck
Original Message
From: Andy Schwarz <phyaks@p...>
To: basicstamps@egroups.com <basicstamps@egroups.com>
Date: Tuesday, October 10, 2000 11:21 AM
Subject: [noparse][[/noparse]basicstamps] Timing with the BS2
>I am working on a device that measures the deacceleration of balls as
>they pass through light gates but I'm having a problem with the
>timing
>using the BS2. It times in 2us units so the maximum length of time is
>0.131s. If anybody knows how I can time for longer periods to ms
>accuracy please let me know. I tried using a loop with the pause
>command for 1 ms but it then takes 0.3 ms to read the pause
>instruction and 0.3 ms to read the instruction after it so it's no
>good. Any help would be appreciated.
>
>Andy
>
>
>
>
>
Also, I can't find a contact for purchase - anybody have Steve Parkis' email
address to ask him?
Tracy Allen wrote:
> >I am working on a device that measures the deacceleration of balls as
> >they pass through light gates but I'm having a problem with the
> >timing
> >using the BS2. It times in 2us units so the maximum length of time is
> >0.131s. If anybody knows how I can time for longer periods to ms
> >accuracy please let me know. I tried using a loop with the pause
> >command for 1 ms but it then takes 0.3 ms to read the pause
> >instruction and 0.3 ms to read the instruction after it so it's no
> >good. Any help would be appreciated.
>
> Hi Andy,
>
> A tight loop can count the time P0 stays high in units of .713 milliseconds
> on a BS2:
>
> x var word
> timer:
> x=0
> timer0: ' wait here until P0 goes high
> branch in0,[noparse][[/noparse]wait2start]
> timer1: ' 1426 loops per second, 7.013E-4 seconds per loop
> x=x+1
> if in0 then timer1 ' count until in0 goes low
> debug dec x**45960," milliseconds",cr ' ** converts to millisecs.
> goto timer
>
> True, there is uncertainty in the result due to the loop processing time.
> Here are links to external timer chips made for the stamp:
>
> http://home.earthlink.net/~parkiss/tm1summ.txt
> http://www.phanderson.com/timer_1_2.html
> http://www.al-williams.com/awce/pak7.htm
>
> I hope that helps
> -- Tracy Allen
> electronically monitored ecosystems
> http://www.emesystems.com
>Also, I can't find a contact for purchase - anybody have Steve Parkis'
email
>address to ask him?
>> http://home.earthlink.net/~parkiss/tm1summ.txt
Timing resolution to 1 microsecond in 71.5 or more minutes.
mailto:parkiss@e...
Steve is active on this list. The last time I talked with him, he was
heading off with a backpack to the Grand Canyon. So you might not get an
immediate reply!
Steve provides the Scenix source code for the TM-1 there on his site:
http://home.earthlink.net/~parkiss/tm1sxcod.txt
If you have an SX-key or an SX-blitz from Parallax you can burn your own
chip.
-- Tracy Allen
electronically monitored ecosystems
http://www.emesystems.com