PIC32 needs a filter on the ICSP/power supply wires

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takao21203

Joined Apr 28, 2012
3,696
There is too much noise on the LED matrixx board, the PIC runs at 80 MHz internally, powered it up a few days ago, and each time I moved my hand near the ICSP pins or the orange wires, the PIC actually stopped (LED stops blinking).

One morning I came up with the weird idea to wrap a shielding wire around the 5 ICSP wires (2 also for power supply via 2 LED from 5v), short it together, and ground that.

It worked instantly, even touching the PIC32 anywhere does not cause any reaction at all anymore. maybe the beads are not required, did not test.

The 22uH inductor in the Vcc line is required too, just the shielding alone or the inductor dont do the job. Tried that, removed it, same problem again.

Yes I know the PIC32 board looks messy, its very old, was a gift I received, see date stamp on the PCB, actually the first TQFP chip I ever soldered.

It has 512K FLASH and 128K RAM, and 80 MHz, not a bad IC for that time.
 

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