18F8720 program area failed

Proggy · Joined: 24 Nov 2003 Posts: 1

I have a board populated with a 18F8720 that I have been trying to program but with no success. I have tried programming with the Warp13 and the ICD2 (both using ICSP) and both fail at programming the program memory. They don't even program one bit or byte in the program memory. They do however program the data eeprom correctly. I have checked the voltages on all supply pins including AVdd and everything is correct (+5.0Vdc). This seems a bit strange when the data eeprom can be programmed and nothing else. Has anyone come across this this type of problem?

Douglas Kennedy · Joined: 07 Sep 2003 Posts: 755 Location: Florida

The 18F8720 comes from the factory with the fuse set in LVP mode. To take the first download at 5V the LVP pin needs to be configured correctly. For some reason some of these chips won't easily come out of LVP mode. Make sure there is a good common ground between the programmer and the 18F8720. My experience is once you get them to take the first download in NOLVP mode they will behave after that. I've had success with using PICstart ( Microchip has pinouts for an adapter to bring out ICSP from the PICstart).
The PICSTART has the ability to drive the resetting of the fuse to NOLVP on the first download which on some 18F8720's other programmers can't.