Incorrect Device ID at 5VDC?

ninjanick · Joined: 25 May 2004 Posts: 25

ICD-U40 firmware version 1.29
PIC16F87

I've been tracking down a strange occurrence which has got me stumped. On a blank chip I can program no problems, but when I read the device ID it comes up Device ID: 0000. I thought it was a power supply issue so I tried powering the PIC from the ICD (5VDC jumper). This didn't work. I even tried populating a separate board with just the PIC and the MCLR pull up ... still no go. The only way I get it to reliably see the correct device ID (0725) is if I power the pic at between 2.5 - 2.89VDC. Above the Device ID is 0000. Below the ID can be 0000 or some other number (ie 0125).

Configuration Fuses have everything off. (ie. NOPROTECT, NOCPD, NOWRT, etc ...) So I'm not really sure what to think. I thought supplying more voltage makes programming more stable ... or at least allows a Bulk Erase of the PIC.

PIC has an 03 date code, but I asked Microchip and they said they have not heard of such an issue.

Haplo · Joined: 06 Sep 2003 Posts: 659 Location: Sydney, Australia

Have you tried reading the DeviceID in the code, running at 5v? If this returns the correct value it will mean there is a problem with ICD.

ninjanick · Joined: 25 May 2004 Posts: 25

Not sure what you mean by in the code? I read the Device ID using the Advance Menu in the ICD.exe program. I can't read the chip at 5VDC after I program it. ICD.exe can't read the target PIC. The only way I can write to the chip is if I do a chip erase at 2.8VDC and another at 5VDC. Then I can read the target PIC and write to it.

Haplo · Joined: 06 Sep 2003 Posts: 659 Location: Sydney, Australia

Take a look at this post on how to read the device ID in the code:

http://www.ccsinfo.com/forum/viewtopic.php?p=31536

Andreas · Guest

Hi,

If You have Revison 03 Chipy call Microchip again, they have a complete
bad batch with rev 03!!

I was searching for a thermal problem in a rather large project with PICS failing from time to time. Everything pointed to a software problem, after searching hardware and software I called the local Microchip Rep and he told me Yes its a known problem with Rev 03 !!!!

This chips fails sometimes at temperatures below 40� C.

best regards

Andreas

ninjanick · Joined: 25 May 2004 Posts: 25

Andreas,
I called my local Microchip rep and they don't have any record of problems with 03 data code chips. But I have seen some issues on the forums where people were complaing about 03 date code chips.

Haplo,
I don't have an RS232 chip to read out the data registers for the Device ID. I will try to acquire one, but the Device ID is read successfully on a blank chip at 5VDC and a programmed chip at 2.8VDC.

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

ninjanick · Joined: 25 May 2004 Posts: 25

Ok scratch that ... I mean the way I've been programming them seems pretty reliable. I will have to order a new batch and see if 04 date code chips behave the same or differently.