PICKIT2 Vdd Voltage

[photonix]

Hello,

I've just got my PICkit2 2 days ago, I've tried it with 16F688,
18F1320, 18F2520, it worked fine. Yesterday I tried it with 16F88, the
chip could be programmed quite well, but the erase didn't. After I
erase, I use blank check to check whether it is blank, and the device
is not blank.Then I read the (erased??) chip in my JDM based
programmer, it isn't blank. What is the possible problem cause that ?
After I programmed the PIC, I use PICkit2 to power the target, with
16F688, it worked fine, the application run correctly. But if I power
the 16F88 with PICkit2, the chip refused to work, no response, so I
tried to power the 16F88 from my 5V Wall wart power supply, and it
worked well. Then I measured the Vdd output from PICkit2, Vdd
approximately about 4V, didn't it suppose to be close to 5V? 16F688 can
work in wider voltage range so it worked, but 16F88 didn't. Is it
normal that my PICkit2 Vdd voltage just 4V. I tried my friend's
PICkit2, but the Vdd voltage also approximately 4V. Is there some
problem with the PICkit2 or my PC USB Port? Thanks..........

regards,

Albert

[Xiaofan Chen]

I would say 4V from USB is possible. From the posts in Microchip
forum of destroyed PICKit2 , I think it is a bad idea to power
external circuits with PICkit 2. It has limited driving capability and
very little protection of the programming interface.

As for 16F88, the second config word is not supported. Maybe that is
the reason that blank_check will fail. Take note that 16F88 is not listed
as a officially supported chip by PICkit 2.

Regards,
Xiaofan

[photonix]

I also think it is bad idea to power circuit directly because of USB
power capability. I'll used Wall Wart Power Supply next time.
Yes, PIC16F88 is not officially supported as you said, but it
programmed and verified well so far , so it's OK for me. Thanks

Regards,

Albert

[photonix]

[photonix]

I'll power my circuit from PS next time, bacause I don't want to
destroy my PICkit2. PIC16F88 gets programmed and verified well in my
place so far, so it's OK for me right now. Thanks.

Regards,

Albert

[art-666]

I have not got into the PicKit2 power to Vdd yet, but looking at the
Schematic pin 13 of Pic18F2550 is named Vdd_Trg_Adj, so this voltage is
adjusable.
So does anyone see 3v3 to 6v2 at this pin? as in levels from a
production programmer.

Regards,

Art

[Xiaofan Chen]

I think this has not been implemented. I believe this feature is to support
the future 18J/PIC24/dsPIC33 PICs.

Please also take note that the so called "production programmer" where
verification is done through different Vdd range might not be necessary
for newer flash PICs. I am not 100% sure about this but some programming
specifications do not mention this any more.

Regards,
Xiaofan