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Forum Index : Microcontroller and PC projects : PicoMite: Counting Input Questions

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DrifterNL

Regular Member

Joined: 27/09/2018
Location: Netherlands
Posts: 58
Posted: 03:37am 21 Dec 2022
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Hi again,
What is the maximum frequency and minimum pulse length that can be used on a pin configured for counting to still get a reliable count?
Floating Point Keeps Sinking Me!
Back To Integer So I Don't Get Injured.
 
IanRogers

Senior Member

Joined: 09/12/2022
Location: United Kingdom
Posts: 151
Posted: 08:47am 21 Dec 2022
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Did you read this thread..

www.thebackshed.com/forum/ViewTopic.php?FID=16&TID=15380

Sorry can seem to make a link
Edited 2022-12-21 18:51 by IanRogers
I'd give my left arm to be ambidextrous
 
Volhout
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Joined: 05/03/2018
Location: Netherlands
Posts: 5089
Posted: 01:45pm 21 Dec 2022
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Short answer:

The picomite SETPIN gpx,FIN function

Up to 50kHz it is accurate error < 1%
Up to 200kHz you are looking at 2-3 % error
Up to 500kHz you have up to 20% error

It also depends on the CPU load. in example, if you have OPTION AUDIO set,the CPU can be more busy and faults get larger.

Volhout
Edited 2022-12-21 23:46 by Volhout
PicomiteVGA PETSCII ROBOTS
 
matherp
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Joined: 11/12/2012
Location: United Kingdom
Posts: 10310
Posted: 02:37pm 21 Dec 2022
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Try V5.07.06b6 - accuracy much improved. Tested at 500KHz with CPU speed 378MHz.
 
DrifterNL

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Joined: 27/09/2018
Location: Netherlands
Posts: 58
Posted: 03:03pm 21 Dec 2022
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Hi all,

I'm actually asking about the SETPIN pin,CIN function, and how high the frequency and short the pulse can be before the picomite starts to miscount.
I'm using V5.07.05b15
Edited 2022-12-22 01:06 by DrifterNL
Floating Point Keeps Sinking Me!
Back To Integer So I Don't Get Injured.
 
matherp
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Joined: 11/12/2012
Location: United Kingdom
Posts: 10310
Posted: 03:14pm 21 Dec 2022
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Use 5.07.06b6 it improves FIN, CIN, and PER

At base CPU frequency I've just tested with 200KHz and pulse width of about 40nS
CIN behaves the same as FIN
Edited 2022-12-22 01:16 by matherp
 
DrifterNL

Regular Member

Joined: 27/09/2018
Location: Netherlands
Posts: 58
Posted: 07:25pm 21 Dec 2022
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Thanks for all the responses.  
Looking at the posted frequencies and pulse width the PicoMite should easily count pulses that have a width of ~5ms and frequency of ~28Hz.
I'll be sure to update to the latest firmware.
Floating Point Keeps Sinking Me!
Back To Integer So I Don't Get Injured.
 
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