General usage documentation issues

[znmeb]

I just got a SparkFun Pro RP2350 and I'm trying to get the examples to build. I've run into a few issues I could fix via web search, but there are some outstanding ones:

1. RISC-V compilers: The README says to use stable but the C/C++ SDK manual PDF says to use top-of-tree. Who's right? Will both of them work?
2. The CMake step says: Skipping universal examples as PICO_RISCV_TOOLCHAIN_PATH and PICO_ARM_TOOLCHAIN_PATH are not defined. Where is the documentation on how to set these?
3. CMake: Skipping TinyUSB dual examples, as TinyUSB hw/mcu/raspberry_pi/Pico-PIO-USB submodule unavailable. How do I get that submodule?
4. FreeRtOS:

Using FREERTOS_KERNEL_PATH from environment ('/var/home/znmeb/dbx-homes/CLAMS-PicoSDK/pico/FreeRTOS-Kernel')
CMake Error at freertos/FreeRTOS_Kernel_import.cmake:87 (message):
  Directory '/var/home/znmeb/dbx-homes/CLAMS-PicoSDK/pico/FreeRTOS-Kernel'
  does not contain a 'rp2350-arm-s' port here:
  portable/ThirdParty/Community-Supported-Ports/GCC/RP2350_ARM_NTZ

How do I get the rp2350-arm-s port? A web search didn't turn anything up, so I assume either it hasn't been released yet or the search engines haven't indexed it.

[lurch]

pinging @nathan-contino for questions about the documentation and @will-v-pi for questions about the RISC-V compilers.

CMake: Skipping TinyUSB dual examples, as TinyUSB hw/mcu/raspberry_pi/Pico-PIO-USB submodule unavailable. How do I get that submodule?

Hmmm, TinyUSB used to use submodules, but it looks like it now uses a dedicated script for downloading dependencies (see https://docs.tinyusb.org/en/latest/reference/getting_started.html#dependencies ) so I guess the message at https://github.com/raspberrypi/pico-examples/blob/develop/usb/CMakeLists.txt#L18 needs updating to not mention submodules.

So it seems the complete set of steps is:

git clone https://github.com/raspberrypi/pico-sdk.git
cd pico-sdk
git submodule update --init
cd lib/tinyusb
python3 tools/get_deps.py rp2040

[will-v-pi]

1. My personal recommendation for Risc-V compilers (and what the VS Code extension uses) would be the Core-V top of tree here, or for Pi my pico-sdk-tools one from here
2. It’s not documented - just set them as CMake variables (-DPICO_ARM_TOOLCHAIN_PATH=…) - they’re not part of the SDK, just part of the Universal Binary examples, as those require both an Arm and a RISC-V compiler
3. Pinging @liamfraser as he was looking into this?
4. Use this kernel for now, there are plans to get the port merged upstream, but I don’t think it’s happened yet

[znmeb]

1. My personal recommendation for Risc-V compilers (and what the VS Code extension uses) would be the Core-V top of tree here, or for Pi my pico-sdk-tools one from here

I'm using the top-of-tree because I built my setup scripts using the SDK manual and didn't want to use stable, which is older.

2. It’s not documented - just set them as CMake variables (`-DPICO_ARM_TOOLCHAIN_PATH=…`) - they’re not part of the SDK, just part of the Universal Binary examples, as those require both an Arm and a RISC-V compiler

Ah ... that's what I figured. But which PATH? /usr/local and it finds everything or /usr/local/bin or something else?

3. Pinging @liamfraser as he was looking into this?

4. Use [this kernel](https://github.com/raspberrypi/FreeRTOS-Kernel) for now, there are plans to get the port merged upstream, but I don’t think it’s happened yet

Yeah - I found that repo after I opened the issue and I have it working now.

[will-v-pi]

Ah ... that's what I figured. But which PATH? /usr/local and it finds everything or /usr/local/bin or something else?

The same path you’d use for PICO_TOOLCHAIN_PATH, which is documented in the C SDK book. If your compiler is /usr/local/bin/arm-none-eabi-gcc then /usr/local should work

[znmeb]

Ah ... that's what I figured. But which PATH? /usr/local and it finds everything or /usr/local/bin or something else?

The same path you’d use for PICO_TOOLCHAIN_PATH, which is documented in the C SDK book. If your compiler is /usr/local/bin/arm-none-eabi-gcc then /usr/local should work

I couldn't get this to work. I looked at the source and it looked to me like there was only one example in the "universal" set, an example of how to build a uf2 that would run either as Arm or RISC-V. That's not something I have an immediate need for, so I can wait for a newer release.

I also looked at the TinyUSB dual case. It doesn't look like there are any examples yet, just examples for host and device. So again, I can wait for a newer release. You can close this unless you want me to do more troubleshooting on the universal case, since I have hardware.

[lurch]

I also looked at the TinyUSB dual case. It doesn't look like there are any examples yet, just examples for host and device.

This part of README.md says otherwise?

Although perhaps that also needs updating, as https://github.com/hathach/tinyusb/tree/master/examples/dual now has host_hid_to_device_cdc and host_info_to_device_cdc.