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Forum Index : Microcontroller and PC projects : MicroMite Beta 17

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OA47

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Joined: 11/04/2012
Location: Australia
Posts: 986
Posted: 11:51am 13 Apr 2014
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  WhiteWizzard said   Keith, Graeme:
Are you using the 40MHz or 50MHz versions of the 28pin PICs??

Graeme: The 150 or 250??

Thanks . . .

PS: I will look at this on analyser when I get home to see if I can work out what is happening.


I am using the 150 chips.

 
Geoffg

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Joined: 06/06/2011
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Posted: 12:49pm 13 Apr 2014
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Thanks Graeme and Keith,

The 1-wire routines use software loops for timing and that could be the source of the problem. These loops should compensate for changes in the CPU speed but the problem might be that they cannot accurate execute the short timings at the slow clock speed.

I will check further.

Geoff
Geoff Graham - http://geoffg.net
 
Geoffg

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Posts: 3292
Posted: 02:59pm 13 Apr 2014
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OK, that was the problem. It will be fixed in the final release.

Thanks again fellows,
Geoff
Geoff Graham - http://geoffg.net
 
OA47

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Posts: 986
Posted: 11:41am 26 Apr 2014
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  Geoffg said   Thanks Graeme and Keith,

The 1-wire routines use software loops for timing and that could be the source of the problem. These loops should compensate for changes in the CPU speed but the problem might be that they cannot accurate execute the short timings at the slow clock speed.

I will check further.

Geoff


  Quote  OK, that was the problem. It will be fixed in the final release.

Thanks again fellows,
Geoff


It still seems that there is an issue with the DS18B20 at low frequency setting in the final release. When CPU 5 is set and a request for temperature measurement is made the error "cpu speed too low " is returned. I am using the micromite in a remote solar powered situation and any saving in power use is sought after.

Just one to keep in mind.
 
TassyJim

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Joined: 07/08/2011
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Posts: 6283
Posted: 01:24pm 26 Apr 2014
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  Graeme Meager said  
It still seems that there is an issue with the DS18B20 at low frequency setting in the final release. When CPU 5 is set and a request for temperature measurement is made the error "cpu speed too low " is returned. I am using the micromite in a remote solar powered situation and any saving in power use is sought after.

Just one to keep in mind.

Could you change the CPU speed to a higher setting for the DS18B20 routine and then change it back to 5MHz afterwards?

I was planning on doing speed changes in a solar powered installation to save power when the micromite is waiting for events of interest to occur.

Jim
VK7JH
MMedit
 
OA47

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Joined: 11/04/2012
Location: Australia
Posts: 986
Posted: 01:48pm 26 Apr 2014
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Excellent thought Jim. Isn't it great that there are more ways to skin a cat
 
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