PICKit 2 Clone - hardware problem

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Slobodan
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PICKit 2 Clone - hardware problem

Postby Slobodan » Mon Oct 23, 2017 4:53 pm

I have this clone, that I have bought years ago, when I tried (and failed) to learn programming. So, I actually never used it.

Now, that I bought FlowCode, I want to use it. So, I have connected it to the computer and opened Microchip PICKit program, and clicked on Troubleshoot. In there I can check voltages on PICKit output pins. All voltages are fine, except when MCLR pin (pin 1) is supposed to be low. For me, it is 3,75V. When it is high it is 4,4V (which is fine). But it does not go low.

BTW, this clone usess same firmware as original PICKit 2, but without programmer-to-go function and LF uC support.
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Last edited by Slobodan on Mon Oct 23, 2017 4:58 pm, edited 1 time in total.

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Re: PICKit 2 Clone - hardware problem

Postby Slobodan » Mon Oct 23, 2017 4:55 pm

Here is the schematics.

I have changed Q5 (BS250), and Q4 (BS170), and it is still the same. Q6 is turned on, so the pin 1 is pulled to the ground, but there is a parasite diode in Q5 that causes problems? Q5 should be fully off. I get 3,75V when pin 1 should be low.
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Re: PICKit 2 Clone - hardware problem

Postby Benj » Mon Oct 23, 2017 5:03 pm

Hello,

What chip are you trying to program, could it be that PICkit 2 doesn't support it?

I've personally not tried a PICkit2 clone but from my experience of the PICkit 2 were pretty bullet proof so it's a bit strange that you're having a problem if they copied the design and components when designing the clone.

For the time and money I would invest in an official PICkit 3. They are a bit more prone to failure (I tend to use mine a lot so 2 at work and 2 at home) but every time one of mine dies I simply write to Microchip and they send free replacements.

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Re: PICKit 2 Clone - hardware problem

Postby Slobodan » Mon Oct 23, 2017 5:11 pm

I did not try to program it yet, because I need to fix this issue first. I don't think this is how PICKit 2 should behave (but maybe it is?). Can anyone who has a genuine PICKit 2 tell me what voltage they have on MCLR pin in Troubleshoot mode?

I wanted to try to program PIC12F629, to see if my programmer works at all, and if it works with FlowCode.

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Re: PICKit 2 Clone - hardware problem

Postby Benj » Mon Oct 23, 2017 5:25 pm

Hello,

With nothing connected to the PICkit2 I get the following voltages on pin1 (MCLR) relative to pin 3 (GND).

Test VPP - 11.92V
MCLR On - 0V
MCLR Off - 0V

On your hardware that you're connecting how is the MCLR pin connected to VCC? We usually connect a 10K pull up resistor between MCLR and VCC to separate the two. If your pull up is too low a resistance then the FETs in the PICkit won't be able to pull low correctly and will also be pulling VCC low.
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Re: PICKit 2 Clone - hardware problem

Postby Slobodan » Mon Oct 23, 2017 5:41 pm

Vpp = 12V
MCLR on: 3,75V
MCLR off: 4,4V (this should show high voltage but you get 0V, hmm?)

This is mine, with nothing connected to the PICKit 2 pins.

On a breadboard, I have prepared an ICSP circuit as suggested by Microchip. I don't have a schematics drawn for it, but it is like on the page 4: http://ww1.microchip.com/downloads/en/D ... 31028a.pdf
I have used about 10K or so resistors, and 100nF capacitor.

But, I have not connected PICKit 2 to this circuit yet, I have just tested it unconnected.
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Re: PICKit 2 Clone - hardware problem

Postby Benj » Mon Oct 23, 2017 5:43 pm

Please note I dug the PICkit2 out of a drawer so it may be damaged, I've not used it for at least 6 years. Though saying this it has just detected an 18F chip no problem so seems to be ok.