raspberry-pi-pico2

# Raspberry Pi Pico 2 and Debug Probe This skill covers development with Raspberry Pi Pico 2 (RP2350) boards and the Raspberry Pi Debug Probe. It includes hardware specs, SDK setup, build configuration, debugging workflows, and common pitfalls. ## Reference Files Consult these for detailed technical content. Read only the file relevant to the current task: - `references/pico2-hardware.md` - RP2350 specs, RP2040 vs RP2350 comparison, pin layout, wireless variant, security features, chip variants - `references/debug-probe.md` - Debug Probe hardware, wiring diagrams, OpenOCD setup, GDB workflow, UART serial, RTT, VS Code integration, rescue mode, troubleshooting - `references/sdk-toolchain.md` - pico-sdk setup, CMake configuration, ARM vs RISC-V builds, picotool commands, MicroPython/CircuitPython, project structure ## Quick Reference ### Board Selection (CMake) | Board | CMake Flag | Platform | |-------|-----------|----------| | Pico 1 | `-DPICO_BOARD=pico` (default) | rp2040 | | Pico 1 W | `-DPICO_BOARD=pico_w` | rp2040 | | Pico 2 | `-DPICO_BOARD=pico2` | rp2350-arm-s | | Pico 2 W | `-DPICO_BOARD=pico2_w` | rp2350-arm-s | | Pico 2 RISC-V | `-DPICO_BOARD=pico2 -DPICO_PLATFORM=rp2350-riscv` | rp2350-riscv | ### Debug Probe Wiring (SWD) | Debug Probe "D" Pin | Wire Colour | Pico 2 SWD Pad | |---------------------|-------------|-----------------| | SC | Orange | SWCLK | | GND | Black | GND | | SD | Yellow | SWDIO | ### Debug Probe Wiring (UART) | Debug Probe "U" Pin | Wire Colour | Pico 2 Pin | GPIO | |---------------------|-------------|------------|------| | TX | Orange | Pin 2 | GP1 (RX) | | RX | Yellow | Pin 1 | GP0 (TX) | | GND | Black | Pin 3 | GND | Note the crossover: probe TX to Pico RX, probe RX to Pico TX. ### OpenOCD Target Configs | Target | Config File | |--------|------------| | Pico 1 (RP2040) | `target/rp2040.cfg` | | Pico 2 (RP2350) | `target/rp2350.cfg` | | Pico 2 RISC-V | `target/rp2350.cfg` with `-c "set USE_CORE { rv0 rv1 }"` | | Rescue (RP2350) | `target/rp2350.cfg` with `-c "set RESCUE 1"` | ### Typical Debug Session ```bash # Terminal 1: OpenOCD openocd -f interface/cmsis-dap.cfg -f target/rp2350.cfg -c "adapter speed 5000" # Terminal 2: GDB arm-none-eabi-gdb my_app.elf (gdb) target remote localhost:3333 (gdb) monitor reset init (gdb) load (gdb) break main (gdb) continue ``` ### Flash via SWD ```bash openocd -f interface/cmsis-dap.cfg -f target/rp2350.cfg \ -c "adapter speed 5000" \ -c "program my_app.elf verify reset exit" ``` Use the `.elf` file for SWD flashing, not `.uf2`. ## Gotchas These are the most common mistakes and non-obvious behaviours. Pay close attention. 1. **SDK defaults to Pico 1.** You must explicitly pass `-DPICO_BOARD=pico2` to target RP2350. Forgetting this builds for RP2040 and the binary will not run on a Pico 2. 2. **Use the Raspberry Pi fork of OpenOCD.** Upstream OpenOCD (0.12.0) lacks full RP2350 support. Clone from `https://github.com/raspberrypi/openocd.git` branch `rpi-common`. 3. **Wrong target config = failed connection.** Using `rp2040.cfg` with a Pico 2 silently fails. Always match the target config to the chip. 4. **SWD uses .elf, BOOTSEL uses .uf2.** These are different formats for different flashing methods. Do not try to flash a .uf2 via OpenOCD/SWD. 5. **Debug builds required for meaningful debugging.** Always pass `-DCMAKE_BUILD_TYPE=Debug` to cmake. Release builds optimise away variable state and reorder code, making breakpoints unreliable. 6. **RISC-V mode has no FPU.** The hardware floating-point unit is only available on Cortex-M33. RISC-V mode uses software float, which is significantly slower for float-heavy code. 7. **RISC-V requires a clean build directory.** When switching between ARM and RISC-V, delete the build directory and re-run cmake. In-place switching does not work. 8. **RISC-V debugging requires pre-selection.** The RP2350 boots into Cortex-M33 by default. To debug RISC-V: `picotool reboot -u -c riscv`, then use OpenOCD with `set USE_CORE { rv0 rv1 }`. 9. **Debug Probe does not power the target.** The Pico 2 must be powered via its own USB or VSYS. The SWD connector carries no power. 10. **LED pin differs on wireless models.** Non-wireless Pico 2 uses GP25 for the onboard LED. Pico 2 W uses WL_GPIO0 through the CYW43439 wireless chip. Code must be conditional. 11. **Git submodules are required.** The pico-sdk needs `git submodule update --init` to pull tinyusb, cyw43-driver, lwip, btstack, and mbedtls. Missing submodules cause cryptic build failures. 12. **OTP is irreversible.** Writing OTP bits is permanent. Misconfiguring secure boot (setting `SECURE_BOOT_ENABLE` without a boot key and with PICOBOOT disabled) permanently bricks the device. 13. **Wireless SPI pin sharing.** On Pico 2 W, the VSYS ADC reading and CYW43439 IRQ checking are blocked during SPI transactions to the wireless chip. 14. **Connect GND first.** When the Pico 2 is powered from a separate source, connect GND between the target and Debug Probe before any signal lines. Voltage differences can damage the probe. 15. **macOS: OpenOCD needs hidapi and libusb.** Install via `brew install hidapi libusb`. If OpenOCD cannot find the probe, check no other process (VS Code, another OpenOCD instance) holds the USB device. 16. **Multiple debug probes.** If multiple CMSIS-DAP devices are connected, specify the serial number: `adapter serial <serial_number>` in your OpenOCD config.