Cannot Read Target VDD?

ninjanick · Joined: 25 May 2004 Posts: 25

I'm using an ICDU-40 to program a PIC16F628A. I can erase the chip and read the Device ID, however it cannot read the target VDD. I'm using the ICD to power the device for programming. MCLR functions normally (using PIC16 Interface GUI). The only reason I ask is because I can't seem to program the device. The ICD programs ok, but during verification the values are not correct.
Not sure if this is an indication of another problem, but whenever I do program the device, the status bar is slow and choppy. I've programmed other PICs before and this is the first time this has happened. It can't be an ICD issue because I can program other devices fine. I doubt it's a cable issue because I can trace the ICD interface directly to the device pins. So I'm kinda' stuck as to what to try next.

treitmey · Joined: 23 Jan 2004 Posts: 1094 Location: Appleton,WI USA

So maybe its a program issue. Do you use LVP or anything else that is "new" to you and the programming of a chip?

I guess what I am saying is ...
What are the new variables???
1) new chip, new board, new ICD cable, new power on ICD
2)....
3)...
4)..
5).

ninjanick · Joined: 25 May 2004 Posts: 25

Basically it's a new chip and board. I'm using the same ICD, firmware, etc ... The programming cable that connects the ICD is new, but I traced all the leads back to the corresponding pins on the RJ11. I even double checked them tonight. It's just wierd.

treitmey · Joined: 23 Jan 2004 Posts: 1094 Location: Appleton,WI USA

I don't know if this is possible for you,... but try this.

1.Power the board. Don't power through ICD.(it may be too much of a load)
2.Check the crystal. See that you have a oscilator.
3.Try to use know "good" everything else,.. code, cables, compiler.
4.Check that the voltage on the board is correct.

5.Remove anything "extra" from the board. Chips, ect.. that could be createing the problem. (This step is a last resort) Try other things first.

6.Make sure the chip is the one you thought you were using... : )
I say this just because I soldered on a 16Lf877a when I wanted a 16f877a
and that problem bit me for 3 hr. the other day. It happens.

Nandini · Joined: 13 Jul 2005 Posts: 15

Are you using the internal oscillator and nomclr fuse. It might cause some issues with entering into programming mode.