8-bit acorn hardware • Re: RGB to HDMI using a Pi Zero and a small CPLD

I know there are some differences in the commercially produced boards - will DIY adapters work ok with the CJE boards?

Yes.

And a couple more Qs whilst I'm at it - are current limiting 220ohm resistors now advised if DIYing as I note that they're all over the commercial boards? And what's P6 for?!

They are 22ohm resistors, not 220ohm. They are meant to add a little protection for the CPLD inputs for things like hot plugging although they wouldn't be required anyway if using an adapter like the analog or PC buffer boards. You could add such resistors in series with the digital RGB signals on a DIN cable as an alternative. Note that putting higher values like several hundred ohms can start to mess up the calibration.

P6 is an alternative hardware reset output from the reset button and can be used to link that up to the reset input on the Pi zero 2 or other Pi models which don't have the two pin reset header.
This is detailed for the DIY boards on the github but it is a separate hole on the CJE boards:
https://github.com/IanSB/RGBtoHDMI/wiki ... ctionality

Also the CJE boards will perform a software reset when the reset button is pressed if the hardware mods aren't made and that works as long as the software is already running. That is useful for those that can't do such mods which may be the case for someone buying a board rather than building it.

Statistics: Posted by IanB — Tue Jun 17, 2025 12:44 am

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