code protection

[eaton]

hello,
I inadvertently programmed a 18f252 with CPD(code protect on). Is it possible to erase this device and re-program? I thought a full erase would bring the chip back to being usable but it doesn't seem to work. Is there something I'm missing or Is this a lesson in paying closer attention to the configuration settings.
I'm using a Microchip ICD 2 to program.

Have a nice day
eaton

[Ttelmah]

A full erase should, _but_ your programmer must be using the high voltage programming mode. The voltage needed to erase this setting, is about the most 'critical' one on the system. How is Vpp wired to your ICD2?. If the resistor on this line is too low, the ICD has problems raising it high enough to disable the code protect, yet most other programming operations will work. The ICD, can connect Vpp, to either 5v, or 12v. It must be connecting it to 12v to erase this setting (verify that the voltage really is going to this value...).

Best Wishes

[Mark]

Make sure that you have the external supply connected.