UIC00B Vdd detection

[ABSF]

How does UIC00B detect the target board Vdd if Pin 8 (Vdd) is NC on the target board? I am referring to SK40C and SK18B startup kits.

I have also found a pickit2 clone schematics here schematics and it looks like the Vdd from the target is detected at VDD_TGT_FB.


Allen

[robosang]

Not really sure how Cytron modify the UIC00B from PICkit 2, but I have try a few configurations. If you are using PICkit 2 Programmer standalone software, basically you can ignore the Vdd setting.
But if you are integrating with MPLAB IDE, you need to take care of that.

I think UIC00B do detect the target board Vdd/Vcc. If the Vdd pin is not connected to UIC00B (example SK40C), you need to make sure the option "Use Target Power Always" is not selected, else the MPLAB IDE will ensure the pin of Vdd/Vcc have 5V or 3.3V before loading program, which in SK40C case, it detect nothing as it is not connected.
Not really sure how SK18B, but you can check the schematic to make sure that.

[ABSF]

Thanks very much for your reply, robosang. The SK18B was the same too, the Vdd pin is NC.

Here is the reply I got from the designer of the clone plckit2

Hi tomasz,

Hello.

> I read your article on the pickit2 clone construction with great interest.  Since it is a pickit2 clone, it should be able to use the pickit2 V2.61 software, right?

Yes, I guess there is no clone that would require firmware modification - it would be very unconvenient (although Microchip pickit 2 firmware is not actively developed now, there would be probably no upgrades).

> I also have another question.  How does the programmer detect the Vdd from the target if Vdd pin is not connected to +5V on the target?  From your circuit diagram,  the target Vdd is detected by VDD_TGT_FB through R15, correct?

Yes.

--Tomasz Ostrowski

Allen