Can I use GPIO extension cable to put Raspberry outside of Amiga?

No, since this is not going to work. The GPIO is used to communicate with the FPGA/CPLD of PiStorm at very high speeds (actually almost as fast as GPIO can) and thus are very sensitive to any noise. The noise in this case can be caused by crosstalk between GPIO wires on the extension cable or signal reflections. It is not going to work.

Can I use microSD extender cable?

That’s complicated. Simple answer is - you shouldn’t. The reason is the same as in case of GPIO extenders - high speed sharp-edged signals guided together over long distances, together with a clock line transmitting at 50MHz and its harmonics. If you are lucky - it will work, but in most cases expect higher number of read/write errors. What can eventually help is reducing the microSD clock rate, the lower the better, at the expense of degraded performance. Best solution would be to not use microSD extenders at all and use other ways to exchange the data (e.g. Wi-Fi or CompactFlash over PCMCIA slot).

Can I connect extra power supply to RaspberryPi?

No! Absolutely no! The 5V rail of Raspberry is powered from your Amiga already. If you connect external power supply there, you will surge power to Amiga from this suppy too. The results will be bad or even worse. If you really feel the Raspberry needs extra power, use either dedicated connector (for example on PiStorm for Amiga 600) or micro USB, but in any way, take the 5V fail from Amiga, not from any external source.

But I saw someone powering whole Amiga through Rasbperry…

This is absolutely unsupported and you SHALL NOT do that! Backpowering whole Amiga from Raspberry will not only put the 5V rail of Raspberry and of PiStorm on higher load. It will also provide only 5V to your Amiga. Other voltages, namely +12V and -12V will be missing. It means, the audio will be horrible, floppy drive eventually not working, serial port definitely not working and many other fancy effects. Just DO NOT DO THAT.

What about RaspberryPi 5?

Short answer: forget it.

Long answer: Unfortunately, the Raspberry Pi Foundation introduced a south-bridge in the Pi5, an additional chip that handles the GPIO, which is crucial for PiStorm’s fast communication between hardware and software. This south-bridge connects to the ARM CPU via a PCIe x4 bus. While the bus itself is excellent for bulk transfers, it has very high setup times, making the GPIO too slow for PiStorm’s needs. We are not the only project affected by this limitation, and the Raspberry Pi Foundation is aware of the issue. As a result, we are currently limited to using the Pi Zero 2 W, Pi 3, Pi 4, and CM4.

Will you be able to use CM5 maybe?

It is highly likely that the CM5 (Compute Module 5) will suffer from the same issue with the GPIO south bridge as the Pi5 (see previous FAQ entry). Therefore, we do not plan to support the CM5 in the future. If a version without the south bridge becomes available, we may reconsider. However, for now, the CM5 is not an option for us.