Hi Sean,

Some time back, lot of hair loss, pulling them out. ;-)
I've had the issues with the ICSP crosstalk a long time back. Eventually, f=
ound
it was due to crosstalk.

NEXT/FEXT originated from old telecom stuff, IIRC.

http://www.flukenetworks.com/blog/cabling-chronicles/cable-testing-101-cros=
s-talk-near-and-far

There were a few suggestions by Olin to reduce the crosstalk, on
different forums.
On his website, he mentions of a GND pin between PGC and PGD

http://www.embedinc.com/picprg/icsp.htm

Sorry, the Resistor/capacitor damping to prevent the fast edges were on the
Microchip forums, not on piclist. I dont remember the exact thread, there w=
as
a small schematic (jpg) too, but unable to find the right url to the
original thread,
but you can see the discussion there.

http://www.microchip.com/forums/m214055.aspx


(*) About PGD and PGC filtering: There was a note on the Microchip
forum (by Olin Lathrop) about programming the dsPIC30F201(**),
suggesting to put 22..47 pF on the PGD and PGC lines to ground near
the target chip. In addition, put a 100 ohm resistor in series with
the PGD line between target chip and the cap. The resistor and cap on
the PGD line low pass filter the PGD signal when it is driven by the
target chip. This reduces the high frequencies that can couple onto
the PGC line. The cap on the PGC line makes it less suceptible to
coupled noise.
(**) We later found out that this important note also applies to the
PIC18Fxxxx family. A user of a Velleman PIC programmer reported
success with a PIC18F4520 after adding 2 * 33 pF caps and a 100 Ohm
series resistor.


Cheers,

Manu


On Mon, Jan 1, 2018 at 10:16 PM, Sean Breheny <shb7@cornell.edu> wrote:
> Hi Manu,
>
> I never heard the term NEXT/FEXT before and when I Google it, it seems to
> be talking about physical crosstalk. What does that have to do with the
> timing issues you mention?
>
> Just trying to understand! Thanks.
>
> Sean
>
>
> On Mon, Jan 1, 2018 at 10:26 AM, Manu Abraham <abraham.manu@gmail.com>
> wrote:
>
>>
>> https://msdn.microsoft.com/en-us/library/windows/hardware/
>> ff540207(v=3Dvs.85).aspx
>>
>> WinUSB is a User Mode Driver framework, Kernelspace drivers comply more =
to
>> timing restrictions etc etc.. So, the userspace timing dictates your bus
>> timing.
>> This is dictates your Near END/ Far END (NEXT/FEXT) crosstalk. IIRC
>> correctly,
>> I've gone through this specific problem. Olin Lathrop has had a
>> suggestion for this
>> issue on this ML, a long time back. This did fix the issue for me.
>>
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