Modifications

Capacitor Modification

This only applies to Pulse Train Hats purchased back in 2017. The new batches being sold in April 2018 onwards have this fix in place.

We have always stated that the Pulse Train Hat Frequency is:

Pulse train speeds of 0.004 HZ to 125kHz output (Recommended 100kHz Max due to buffer switching could cause jitter).

This has not really been an issue as most people are using the PTHAT to run motors and you will hardly ever go over 80kHz.

But we have had a few people wanting to push the board to higher rates and we were a little confused at how our prototype boards could go over 150kHz yet we had people reporting jitter at around 100kHz.

After months of investigation if turns out that when the boards were produced the manufacturers placed 0.1uf capacitors instead of 22pf capacitors on the pulse train output lines.
This is not a great issue, until you start going at speeds past 100kHz and the capacitor starts effecting the rise and fall time.

You can use SMD Ceramic Capacitors 22pf 0805 footprint

So please find below a modification that will allow greater speeds (upto 500kHz) and less jitter!