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My ICD2 (on varia-board) works

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New Member
Since I have no money to fabricate PCB, I have to go to school components store and collect them. My friend Terrence help me a lot, who gave me 18F4550. For others components, I have to buy them from market.

The test result: all pass, including debugging and downloading.
Before this ICD2, I tried "The simplest ICD2", but it failed under MPLAB 7.42.
In addition, the Vpp has some problem: it can not pull MCLR down to ground, (MCLR is pulled-up to Vcc with 10K resistor in the circuit.)

It only spend me 9 Singapore Dollar (around 5.6 US dollar).

Here is my pictures:

schematic + firmware, based on 16F877A/16F877 and 18F4550:
Or you goto the original Website:


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Active Member
Nice project and welcome to the forum.

There are three versions of PCB & schematic of USB ICD2 clone shown at wiki, it helps to indicate in your previous post which version you have built or whether you have changed/left out part of the schematic in your project.

Mike - K8LH

Well-Known Member
Dear SilentSnow,

Your USB-ICD2 looks very nice.

I see in your download that you're using user PiCS' design.

I just received the 'sample' USB connectors I was waiting for and I'm just about to start building user PiCS' design on a small Radio Shack prototype board using the layout below (most components mounted in-between the sip sockets to fit underneath the '877A and '4550).

Kind regards, Mike


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Active Member
Hi Mike,

I have looked at your attached image and did not see any provision to generate the Vpp for programming the target PIC, though I did see the three SPI interface connections.

In another forum you have posted the idea of using a 12F683 with PWM to generate the Vpp while also emulating as an SPI digital pot to the 877. Do you plan to use this method for your above design or something else?

If you still have some interest in using the 12F683, I would agree that all SPI sixteen bits data(command+data) coming from the 877 should be received in one interrupt session, i.e. using only the /CS to initiate an interrupt instead of servicing the SPI_CK signal. Have you decided on this yet?


New Member
Thanks Mike.
Since I have no money to fabricate my own PCB, I had to build the circuit on varia-board.

After all, I am only a student, no need build it so nicely.
I will save your attachment for future.
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