Eugene Lozovoy

Is 3.3V power line stable?

I think this RF dongle maybe drawing too much power. I would buy one for tests probably.

This isn't required. After googling a bit, I found complaints about the compatibility of 8bitdo controllers with zx-uno: https://www.zxuno.com/forum/viewtopic.php?t=3972 This may be caused by the same reason - zx uno...

I bought 8BitDo M30 gamepad with Megadrive Bluetooth receiver and it's works just flawlessly with Sizif-512 (rev.D). So I assume there is some issue with your hardware.

PCB rev.E released with +5 power for gamepad. This should eliminate any theoretical incompatibilities.

Hello I've never dealt with GBS. I suppose there is some incompatibility with Pentagon video signal timings, which is going beyond PAL specifications. Can you check in 48K and 128K...

Ouch, that's unexpected. 48K timings are best in terms of compatibility with TVs. Are you using latest firmware? How GBS is connected to Sizif? Is your TV/Monitor supports 50Hz? Can...

This may be caused by oscilloscope bandwidth limitation.

No. It's have 50MHz bandwidth. To get accurate square waveform at least 10x (280MHz) bandwidth required.