Pico | Pico is a stupidly simple , blazing fast , flat file CMS | Content Management System library

If you want to use precompiled/bytecode .mpy files then you will need to Decide to use either bytecode or compile to native code for your mcu platforms.

For bytecode you will need to distribute a bytecode version that matches the runtime firmware, 1.12-1.18 == 5, next version will increase

For native code you'll need to distribute versions for each platform that you want to support. An esp32c3 cannot run stm32 native code and vice-versa

Also the different ports/board will indeed have differences in some of the stdlib APIs. Your code must be robust enough to handle these differences.

The issue is that you loose correct context for this. You don't pass arrow function to setTimeout, so this will be window or undefined (depending on strict mode). Anyway, you should change your code:

Your code is for micropython. Circuitpython is different. See here https://learn.adafruit.com/circuitpython-essentials/circuitpython-digital-in-out

The message must be superuser to use mount is a hint to a permission problem.

The Linux system expects most system files to be owned by UID 0 (root), but when reading the NFS filesystem set up in the guide it actually reads UID 1000, or the UID of whoever built the system in the development machine. If I list the contents of ${YOCTO_BUILD_DIR}/tmp/work/${TARGET}-poky-linux-gnueabi/${IMAGE}/1.0-r0/rootfs, I get:

Can I suggest that you add:

I don't think you can do this without installing something on the host computer side to detect when the Pico was connected, check what keys were pressed and communicate with the Pico accordingly.

If the host computer is Windows then a quick search finds this which uses Windows Management Instrumentation to run Python code when a USB device changes.

Alternatively, you could attach a hardware button to the Pico and check that button when the Pico detects that it has been connected to a USB host - you appear to have already figured this out.

A switch -- by itself -- doesn't provide power to anything. All it does is close and open a circuit. You can replace the switch with a wire and connect/disconnect the wire and accomplish the same thing.

If you had the middle pin of the switch connected to GPIO 2, and the two outer pins wire to Ground and Vcc, you could use the switch to switch the value of the GPIO between logic 0 and logic 1.

Reading the value would look something like this:

The solution was to change imx7d-pico-pi-m4.dtb to imx7d-pico-pi-qca-m4.dtb in the Yocto/Hardknott/technexion configuration file called pico-imx7.conf(described in the post)

There are a couple of concepts to disentangle here:

(1) Arm vs Thumb : these are two different instruction sets. Most CPUs support both, some support only one. Both are available simultaneously if the CPU supports both. To simplify a little bit, if you jump to an address with the least significant bit set that means "go to Thumb mode", and jumping to an address with that bit clear means "go to Arm mode". (Interworking is a touch more complicated than that, but that's a good initial mental model.) Note that all Arm instructions are 4 bytes long, but Thumb instructions can be either 2 or 4 bytes long.

(2) A-profile vs M-profile : these are two different families of CPU architecture. M-profile is "microcontrollers"; A-profile is "applications processors", which is "(almost) everything else". M-profile CPUs always support Thumb and only Thumb code. A-profile CPUs support both Arm and Thumb. The Raspberry Pi Pico is a Cortex-M0+, which is M-profile.

(3) QEMU system emulation vs user-mode emulation : these are two different QEMU executables which run guest code in different ways. The system emulation binary (typically qemu-system-arm) runs "bare metal code", eg an entire OS. The guest code has full control and can handle exceptions, write to hardware devices, etc. The user emulation binary (typically qemu-arm) is for running Linux user-space binaries. Guest code is started in unprivileged mode and has access to the usual Linux system calls. For system emulation, which CPU is being emulated depends on what machine type you select with the -M or --machine option. For user-mode emulation, the default CPU is "A-profile with all supported features enabled" (this is --cpu max).

You're currently using qemu-arm which means you get user-mode emulation. This should support Thumb binaries, but unless you pass it a --cpu option it will be using an A-profile CPU. I would also suggest using a newer QEMU for M-profile work, because a lot of M-profile CPU bugs have been fixed since version 4.2. I think 4.2 is also too old to have the Cortex-M0 CPU.

GDB should tell you in the PSR what the T bit is set to -- use that to check whether you're in Thumb mode or Arm mode, rather than looking at how much the PC is incrementing by.

There's currently no QEMU system emulation of the Raspberry Pi Pico (though somebody has been doing some experimental work on one). If your assembly is just basic "working with registers and a bit of memory" you can do that with the user-mode emulator. Or you can try the 'microbit' machine model, which is a Cortex-M0 board -- if you're not doing things that are specific to the Pi Pico that might be good enough.