Thanks a lot for stepping in! The core I’m using is the recommended one by Earle Philhower, and the Tiny2040 is on the compatibilty list.
The other posts referring to SPI pin problems are these:
https://forums.pimoroni.com/t/which-are-the-spi-pins-on-tiny-2040/17450/16
https://forums.pimoroni.com/t/tiny-2040-display-watch/17843/24?page=2
Especially the latter one drove me to think the pinout diagram might not be correct. People seem to try and connect just about every pin arbitrarily to get things to work, even with Python.
I’m well aware the pin flexibility of the RP2040 introduces some difficulties and is confusing many people including me. Sadly, support for the C/C++ side looks rather sparse since a majority of people seems to use the chip with Micropython/CircuitPython. That makes good sense, but my problem in question circles around the RFM69 implementation in Python which is based on the RadioHead communication settings, which in turn are not compatible with the LowPowerLab approach, while the RadioHead library is reported to have some bugs in certain environments…
So for my setup I’m forced to utilize C/C++ right now - and I’m wondering if I miss SPI init steps here, because the information available on how to use SPI (and interrupts) with the RP2040 in the C/C++ environment looks somewhat unambiguous to me.
I understand the pins GP0 to GP7 can utilize SPI0. But do I have to somehow introduce the pins I use to the SPI libraries? Are all of these pins mapped automatically to hardware SPI0, so I don’t need to map anything first? I also understand the pins “GP…” need to be named just by their number in the Arduino C/C++ environment - or do they?
Any distinct advice would be greatly appreciated. I’m also well aware the mistake might lie somewhere deep in my setup which is difficult to test or just within my stupidity, but I’ve had success with a Feather M4 as well as with the ItsyBitsy NRF52840 - so getting things to work with the RP2040 seems to be unusually hard, and as already stated, documentation on the C/C++ side seems much less accessible to me than for other chips or RP2040 Python environments. Please excuse my frustrated post - I’ve just tried so many things (maybe too many) and scraped so many websites on this that I’m on the verge of giving up trying to utilize the Tiny 2040 with C/C++.