Use the boards menu to select your model of RP2040 board. There will be two options: Boardname and Boardname (Picoprobe). If you want to use a Picoprobe to upload your sketches and not the default automatic UF2 upload, use the (Picoprobe) option, otherwise use the normal name. No functional or code changes are done because of this.
There is also a Generic board which allows you to individually select things such as flash size or boot2 flash type. Use this if your board isn’t yet fully supported and isn’t working with the normal Raspberry Pi Pico option.
Arduino-Pico supports onboard filesystems which will set aside some of the flash on your board for the filesystem, shrinking the maximum code size allowed. Use this menu to select the desired ratio of filesystem to sketch.
While it is unsupported, the Raspberry Pi Pico RP2040 can often run much faster than the stock 125MHz. Use the CPU Speed menu to select a desired over or underclock speed. If the sketch fails at the higher speed, hold the BOOTSEL while plugging it in to enter update mode and try a lower overclock.
Debug Port and Debug Level
Debug messages from printf and the Core can be printed to a Serial port to allow for easier debugging. Select the desired port and verbosity. Selecting a port for debug output does not stop a sketch from using it for normal operations.
Generic RP2040 Support
If your RP2040 board isn’t in the menus you can still use it with the IDE bu using the Board->Generic RP2040 menu option. You will need to then set the flash size (see above) and tell the IDE how to communicate with the flash chip using the Tools->Boot Stage 2 menu.
Boot Stage 2 Options for Generic RP2040
The Arduino Pico needs to set up its internal flash interface to talk to whatever flash chip is in the system. While all flash chips support a basic (and slow) 1-bit operation using common timings, each different brand (and sometimes model) of flash chip require custom timings to work in QSPI (4-bit) mode. The Boot Stage 2 menu lets you select from the supported timings.
The options with /2 in them divide the system clock by 2 to drive the bus. Options with /4 divide the clock by 4 and so are slower but more compatible.
If you can’t match a chip name in the menu to your flash chip, a simple test can be run to determine which is correct. Simpily load the Blink example, select the first option in the Boot Stage 2 menu, and upload. If that works, note it and continue. Iterate through the options and note which ones work. If an option doesn’t work, unplug the chip and hold the BOOTSEL button down while re-inserting it to enter the ROM uploader mode. (The CPU and flash will not be harmed if the test fails.)
If one of the custom bootloaders (not Generic SPI /2 or /4) worked, use that option to get best performance. If none worked other than the Generic SPI /2 or /4 then use that. The /2 options of all models is preferred as it is faster, but some boards do require /4 on the custom chip interfaces.
When in doubt, Generic SPI /4 should work with any flash chip but is slow.