Hi Bob Thank you for the response. I'm not sure of the procedures in responding to this PIC user group, so if I am contravening the etiquette, please excuse me. We use a suite of Pro Mate 2 programmers. We have programmed more than 2 million parts, albeit mainly 12Cxxx series but we have had no problems with those products. We verify at 3V and 5.5V After programming the PIC's are placed on the PCB's and re-flow soldered. Thereafter they are configured and functionally tested (configuration being accomplished via a "communications link", i.e. the PIC is operational at this point.) The PBA (printed circuit board assembly) is then shipped to a converter who incorporates the board into a product. The boards are tested prior to integration, and then finally configured in the product. The product is then shipped into the field where they are commissioned, indicating full functionality of the integrated PBA. I believe any marginal programming would have shown itself by this time. May I also add that all the failed units "ROM" verify when returned. This is a double edged sword. None of the returned units have had EEPROM (code space) failures, only the configuration bits are changed. Of course the fact that the units have "un-code protected" themselves is a matter of grave concern. Regards Mr Tom Phillips Systems Engineer (Solar) Merlin Gerin SA (Pty) Ltd t/a CONLOG Tel : +27-31-268-1111 (S/Board) +27-31-268-1476 (Direct) Fax : +27-31-208-7790 e-mail : phillipst@conlog.co.za Internet : www.conlog.co.za -----Original Message----- From: Bob Ammerman [mailto:RAMMERMAN@PRODIGY.NET] Sent: 22 September 2000 13:48 To: PICLIST@MITVMA.MIT.EDU Subject: Re: [PIC]:In-situ PIC16F84 configuration bit changes What programmer were they burned with? Does it do proper voltage margining on verify? Bob Ammerman RAm Systems (contract development of high performance, high function, low-level software) ----- Original Message ----- From: Tom Phillips To: Sent: Friday, September 22, 2000 3:51 AM Subject: [PIC]:In-situ PIC16F84 configuration bit changes > Help > > I have PIC16F84 -04I/SO controllers changing their configuration bits on the > fly. Some have been installed for a few weeks, others have been in the > field for two years. The circuits are potted and therefore I can rule out > any tampering. > > Environment : 14 to 21V DC, temperature range -8 deg Celsius to +80 deg > Celsius, outdoors > Oscillator : Murata CSTCS 4.00MHz (integrated 18pF caps) > Original Configuration : OSC=XT, WDT=ON, PUT=ON, CP=ON > Supply : 78DS05F 5V regulator designed for automotive industry > Voltage supervisor : Motorola MC33064 > Source Power-Up : Very slow rise & fall from 0V DC to 19V DC (sometimes in > the region of 20 minutes). > > The reset circuitry has been designed such that the circuit draws more > current in reset than when operational, this stops the supervisory chip > hunting in and out of reset. > > Failed units' configuration bits are generally as follows; OSC=RC, WDT=ON, > PUT=OFF, CP=OFF > > I have also found that we can get some failed units to run normally by > powering them up quickly (normal 5V DC supply). > > Applying a 4MHz oscillator to pin 16 (OSC1) shows the device is still > operational, just that the on board oscillator will not function with the > OSC configuration bit set to RC. > > Has anyone come across something similar, or can anyone suggest reasons for > this anomaly? > > Regards > > Mr Tom Phillips > Systems Engineer (Solar) > Merlin Gerin SA (Pty) Ltd t/a CONLOG > Tel : +27-31-268-1111 (S/Board) > +27-31-268-1476 (Direct) > Fax : +27-31-208-7790 > e-mail : phillipst@conlog.co.za > Internet : www.conlog.co.za > > -- > http://www.piclist.com#nomail Going offline? Don't AutoReply us! > use mailto:listserv@mitvma.mit.edu?body=SET%20PICList%20DIGEST > > -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! use mailto:listserv@mitvma.mit.edu?body=SET%20PICList%20DIGEST -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu