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object01
Joined: 13 May 2004
Posts: 90
Location: Nashville, TN
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| EEPROM blanking spontaneously |
 Posted: Fri Jul 16, 2004 3:15 pm |
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Working with several PIC18F2320s, I'm finding that the EEPROMs sometimes just go blank. I can't predict when they will or why. Has anyone else had this problem?
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Jeff S. |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Fri Jul 16, 2004 5:12 pm |
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Look at the errata sheet for that chip.
http://ww1.microchip.com/downloads/en/DeviceDoc/80187a.pdf
There's a problem with writing to the data eeprom. It lists a
work-around pertaining to the LVD module. You should write
a small test program that writes to data eeprom and check the
.LST file to see if CCS does the work-around. If not, then add
code to do it. See if that fixes the problem. |
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object01
Joined: 13 May 2004
Posts: 90
Location: Nashville, TN
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| Posted: Sat Jul 24, 2004 1:09 pm |
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| PCM programmer wrote: | Look at the errata sheet for that chip.
http://ww1.microchip.com/downloads/en/DeviceDoc/80187a.pdf
There's a problem with writing to the data eeprom. It lists a
work-around pertaining to the LVD module. You should write
a small test program that writes to data eeprom and check the
.LST file to see if CCS does the work-around. If not, then add
code to do it. See if that fixes the problem. |
The errata characterizes this problem as one of data not being written as expected. I'm working on examining the LVD mechanism in the chip, but my EEPROMs are blanking entirely. One value in particular is never written to while the device is running, and it spontaneously blanks (goes to 0xFF) too.
Are the temperature conditions that can cause this?
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Jeff S. |
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SherpaDoug
Joined: 07 Sep 2003
Posts: 1640
Location: Cape Cod Mass USA
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| Posted: Mon Jul 26, 2004 6:47 am |
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Is there any chance the PIC is getting hammered with X rays, maybe from a nearby HV arc, or something simillar? Very high temperatures (exceeding the specs) could do this too.
_________________
The search for better is endless. Instead simply find very good and get the job done. |
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object01
Joined: 13 May 2004
Posts: 90
Location: Nashville, TN
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| Posted: Mon Jul 26, 2004 7:30 am |
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| SherpaDoug wrote: | | Is there any chance the PIC is getting hammered with X rays, maybe from a nearby HV arc, or something simillar? Very high temperatures (exceeding the specs) could do this too. |
It would definitely be a temperature problem, if anything. But I'd have thought being on a car's dashboard on a hot southern day wouldn't exceed the specs.
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Jeff S. |
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Ttelmah
Guest
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| Posted: Mon Jul 26, 2004 10:40 am |
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| object01 wrote: | | SherpaDoug wrote: | | Is there any chance the PIC is getting hammered with X rays, maybe from a nearby HV arc, or something simillar? Very high temperatures (exceeding the specs) could do this too. |
It would definitely be a temperature problem, if anything. But I'd have thought being on a car's dashboard on a hot southern day wouldn't exceed the specs.
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Jeff S. |
Are you kidding!.
I had to do a unit that fits in the top of a truck cab. You are pushing the temperature range, unless you take a lot of care to arrange a method of cooling (for instance, silver foil over the lid of the unit, combined with a heatpipe to the bottom of the vehicle). Why do you think the control electronics on most cars is located on the floor pan?. In direct sunlight, you can boil water comfortably on a metal plate placed under a wind shield, in a much cooler country like the UK...
I'd say there is a 90% chance that heat is the problem.
Best Wishes |
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