Actual LVP Expected NOLVP

[ahinst]

I have just started using the 18F452 in place of the 16F877A and get a rather weird result when programming. After programming I get the fuses as in the subject. I have set the NOLVP in the #fuses after the programming it states Actual LVP. The 47K resistor is in place and I am using the U40 programmer in windows XP. I have installed all the latest updates except the U-40 firmware. When I switch back to the 16F877A it works fine! Both use 20MHz crystal clock. Also some times the PIC18F452 programs and other times it states that all the flash is at FF.

Anybody have any Ideas.

[Ttelmah]

One possibility would be, if you are not doing a 'full erase' (most programmers have an option to enable this), that the WRTC bit is set, so the configuration registers are write protected, in which case if the LVP bit was set in the past, it won't clear in normal programming.

Best Wishes

[ahinst]

Hi Ttelmah,

Thanks for the try. I have checked and the U-40 and associated SW does in fact reset all the bytes including the fuses to FF before loading the HEX file into the PIC. So it must be something else I or the SW is doing wrong.

Any other ideas?

regards

[ahinst]

Hi Ttelmah,

I found it! a lose (dry joint on the MCLR! re-soldering the unit then made it work.

Thanks for you help.

[Ttelmah]

If in doubt, look at the hardware.
Well Done.

Best Wishes