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transitioning to the by tim blythman Raspberry Pi Pico 2 This article explains what you need to do to convert software written for the Raspberry Pi Pico over to the Pico 2. We also take a look at how to use some of its new features. W hile the Pico 2 contains two ARM cores, like the original Pico, they are not the same types (Cortex-M33 rather than Cortex M0), so a UF2 file for the Pico will not work on the Pico 2. However, generally, code written for the Pico can be recompiled to a new UF2 file that will usually work on the Pico 2 without needing further changes. Still, there are a few things to look out for that might trip you up in the process. Generally, the software and tools you use will need to be updated to gain support for the Pico 2. Once you do that, the transition is pretty seamless. Pico 2 challenges Our review of the Pico 2 also highlighted one serious erratum in the RP2350. According to the data sheet, erratum RP2350-E9 applies to the A2 stepping of that processor. As far as we know, this includes the vast majority of RP2350 chips in circulation. It is a fault with the internal pulldown on the GPIO pins, and it can manifest as excessive current being sourced when the pin’s voltage level is between valid high and low levels. The sourced current will oppose the pull-down and can cause the pin to get stuck in the invalid state. The recommended workarounds include not using the pull-downs or to use an external pull-down resistor. We are fortunate in this regard that we have not used this feature in any of our Pico projects, so the RP2350-E9 erratum does not affect our ability to port any of our Pico projects to the Pico 2. If you are using PicoMite BASIC, it provides the option to set the pull-ups and pull-downs from the BASIC interface. So MMBasic projects on the Pico could run afoul of this error if they use the pull-down feature. Table 1 provides a brief overview of our experience in porting our projects to the Pico 2. Note that this doesn’t include contributed projects or those using the Pico W. At the time of writing, the Pico 2 W is not yet available, although we expect it will be shortly. As you can see, most projects simply need recompiling to work with the new processor. So we’ll focus on the changes that have occurred to the individual platforms. Some of these platforms are still under development and might change; we also expect to see more changes when the Pico 2 W is released. C SDK update The C SDK (software development kit) has been updated to version 2.0.0 to coincide with the release of the Pico 2. We have also seen substantial changes to the various tools that accompany the C SDK and these are worth noting. We’ve written about this in more detail in a separate panel, which will be of interest to those readers who wish to set up and use the bare C SDK for programming both the Pico and Pico 2. Table 1 – notes on porting projects to the Pico 2 Besides the silkscreened label, there aren’t many obvious differences from the original Pico. 88 Silicon Chip Project Issue Platform Notes PicoMite Jan 2022 BASIC PicoMite 2 firmware available. Pico BackPack Mar 2022 Multiple PicoMite 2 firmware available. Arduino, C SDK and MicroPython code working without any code changes. VGA PicoMite Jul 2022 BASIC PicoMite 2 firmware available. Pico Analyser Nov 2023 Arduino Minor code changes as noted. Digital Video Mar and Apr Terminal 2024 Arduino MOD1: no code changes, set processor speed to 250MHz. MOD2: no code changes, set processor speed to 120MHz. MOD3: no code changes, set processor speed to 120MHz. Pico Gamer Apr 2024 BASIC PicoMite 2 firmware available. Pico Computer Dec 2024 Multiple PicoMite 2 firmware available. Arduino working without any code changes, although some libraries needed updating. Australia's electronics magazine siliconchip.com.au Arduino support Not long after the original Pico was released, there was an ‘official’ Arduino board profile for the Pico. This also supported the Arduino Nano RP2040 Connect, a WiFi-equipped RP2040 board, although that board profile is now deprecated. A separate project known as ‘arduino-­pico’ was produced not long after. The arduino-pico board profile now appears to be the preferred option for many people, and we have used it for all our Arduino IDE-based Pico projects. The release notes (https://github. com/earlephilhower/arduino-pico/ releases) indicate that version 4.0.0 was the first to support the RP2350 and thus the Pico 2. At the time of writing, version 4.1.1 is current and is what we have been using for testing. So porting an existing arduino-pico project to use the Pico 2 should involve little more than updating the board profile to the most recent version, which can be done from the Boards Manager. The profile defaults to a processor speed of 150MHz for the Pico 2. You might need to try 133MHz, as we have done, in case anything in your code depends on the CPU speed. You’ll see from our notes in Table 1 that some of our projects require other specific processor speeds to work. These and other options are accessible from the Tools menu of the Arduino IDE (see Screen 1). That screen grab shows the option to choose the Board (Pico 2) and the CPU architecture (currently selected as ARM), as well as the greater flash memory capacity (4MB) and CPU speed (150MHz). We have not come across any ‘breaking changes’ so far. We also found that some libraries required an update to work with the Pico 2. Like the arduino-pico board profile, these typically note that the version change is to align with the Pico C SDK versions that support the RP2350 and Pico 2. For many of our Arduino-based projects, we have provided compiled versions (UF2 files) of the projects so you can easily try them out yourself and see that everything still works much the same. At the time of writing, we would say that there is little benefit to switching to the Pico 2 for our existing projects, apart from the Pico 2 Analyser, for the reasons we’ve mentioned. It is more siliconchip.com.au Screen 1: the arduino-pico board profile provides all these options under the Tools menu. The latest versions add the option to compile using the RISC-V architecture, under the CPU Architecture option. expensive and, currently, less widely available. Pico BackPack users would likely benefit from better performance if they use the BackPack for their own custom projects. We may consider updating some projects to add more features or to see if we can improve their performance. For example, MOD1 of the Digital Video Terminal (which produces the video signal) might be able to support higher display resolutions and colour depths. This would potentially use the RP2350’s new HSTX peripheral and would definitely rely on its larger RAM (almost double the size). MicroPython With the Raspberry Pi Foundation directly involved in MicroPython development for the Pico 2, it is not surprising that a very complete MicroPython port was available at around the time of the Pico 2’s release. We haven’t made much use of MicroPython, but had no trouble getting the original Python code from the Pico BackPack to run on a Pico 2 fitted to a BackPack instead of a Pico. Of course, we needed the new Pico 2 MicroPython firmware image to do this. For the software downloads, we have created a firmware image (UF2 file) containing a working copy of MicroPython and the BackPack demo. It can be loaded onto a Pico 2 fitted to a Pico BackPack. More information on MicroPython for the Pico 2 can be found at: https://micropython.org/ download/RPI_PICO2/ PicoMite BASIC We previously noted that development of PicoMite firmware for RP2350based boards (such as the Pico 2) was being documented on The Back Shed Forum (https://thebackshed.com/ forum/ViewTopic.php?TID=17173). This has seen the PicoMite firmware stepping up to version 6.0.0 and includes features like support for Australia's electronics magazine HDMI-compatible video and USB host support for devices like game pads and keyboards, as well as versions supporting VGA. Our February 2025 issue saw the release of the PicoMite 2 firmware (siliconchip.au/Article/17729) and a jump to version 6.00.01 of the Picomite firmware. All these features are now available on the Pico 2, as well as many other boards which use the RP2350 chip. There are six Picomite firmware variants for the Pico 2 as well as four updated variants for the Pico. There are also two WebMite variants, one for the Pico W and one for the Pico 2 W. The firmware can be downloaded from https://geoffg.net/picomite.html Other changes Another interesting feature to note is the update of the “flash_nuke.uf2” file, which completely erases the flash memory of a Pico or Pico 2. There is now a ‘unified’ file which works on both boards, and presumably, other RP2040- and RP2350-based boards. This works because the blocks in a UF2 file format can each contain a processor identification code and the processor can choose to ignore blocks that are not intended for it. In practical terms, the new “flash_ nuke.uf2” consists of individual UF2 March 2025  89 Using the latest C SDK (software development kit) The C SDK consists of headers, libraries and a build (code compilation) system, although other software is needed for a complete development environment. The GitHub repository for the C SDK can be found at https://github.com/ raspberrypi/pico-sdk In our original review of the Pico (December 2021 issue; siliconchip. au/Article/15125), we noted that the instructions for the C SDK were firmly focused on those using a Raspberry Pi computer as their development machine. We tried it out using a Raspberry Pi and found it very easy to use. For setting up a development environment on Windows computers, we also tried the Pico Setup for Windows project at https://github.com/ndabas/ pico-setup-windows Since then, this project has been taken over by the Raspberry Pi Foundation and further development has appeared to cease. Pico Setup for Windows, as the name suggests, was only intended for use with Windows operating systems. It included the cross-platform Visual Studio Code IDE (integrated development environment), also known as VS Code, as well as compilers and other tools. The C SDK has now been made available as an extension for VS Code and now works on Windows, Linux and macOS, so it provides broad, uniform support. This means that setting up the C SDK on just about any computer now involves installing VS Code and then installing the extension for the Pico C SDK. Once installed, the extension can create projects, then compile and upload them to the Pico or Pico 2. It is much more configurable, although we wouldn’t be surprised if our readers found the number of menus and options excessive! It also seems that the files associated with the extension (and their dependencies) add up to several gigabytes. Screen 2: the Pi Pico extension can be installed from this menu within VS Code. The extension requires downloading many files, so it could take a while. Screen 3: the extension adds a new Raspberry Pi Pico Project item to VS Code; it can be found on the sidebar. The options to build & run the project are found there. Screen 4: creating a new project is much the same as in previous versions of the C SDK, except that it can be done from within VS Code. Clicking the Example button creates a new project based on one of the included examples. Setting it up VS Code can be downloaded from https://code.visualstudio.com Interestingly, there are installer options for ARM64 processors running Windows. Run the installer and open VS Code. Screen 2 shows how to install the Extensions; the Ctrl-Shift-X shortcut 90 Silicon Chip Australia's electronics magazine siliconchip.com.au will also open this panel. Search for “pico” and install the Raspberry Pi Pico extension. This will also install dependencies such as C/C++, Python language support and a serial port monitor. After this, you will see a new “Raspberry Pi Pico Project” item down the left side of the VS Code window. Screen 3 shows this along with the options that are now available. You’ll see that there are options for both C/C++ and Python projects. Clicking the “New C/C++ Project” option opens the panel shown in Screen 4. This interface is similar to Project Generator, which was present in older versions of the C SDK. There is also the option to use one of the Example programs as a template for a new project. There is an option to choose either a Pico, Pico W or Pico 2 board and the Pico 2 option allows the code to be compiled to use the RISC-V processor. If you haven’t worked with the C SDK before, we suggest creating a project from one of the examples, such as blink. This simply flashes the Pico 2’s onboard LED; you can modify the delay (LED_DELAY_MS) to check that the changes in the code are having an effect. We also recommend that you use the File → Save Workspace As… option. That will allow you to easily reopen the project’s workspace for later use. Screen 5 shows the workspace for a blink-derived project. At left are the files, including “Cmakelists.txt”. We found that in some of our projects, we have had to manually add references here to hardware libraries (eg, hardware_pwm) in the “target_link_libraries” section for the project to compile correctly. Running the code The Compile Project item in the Pico Project Extension creates a binary file if it succeeds. These files (including the UF2 file for uploading) can be found in the project’s “build” subfolder. The Run Project button will compile and upload the binary file to a Pico device in bootloader mode. The Terminal in the lower half of the screen reports the results of running these commands. You will also find the likes of a Serial Monitor here too. Summary Using VS Code presents a different environment to what we have used for previous versions of the C SDK. Nevertheless, it was easy to set up and use once we became familiar with it. files for the RP2040 and RP2350 that are simply concatenated (joined) together. Theoretically, this system can be used to create UF2 binary files that can be used with numerous processor and board types. To tell them apart, the newer file is around 96kB in size, while the older file is around 25kB. The new file can be downloaded from https://datasheets. raspberrypi.com/soft/flash_nuke.uf2 Picotool We have made good use of the picotool utility for working with Pico boards. It is a command-line program that can interact with a Pico (or other RP2xxx boards) during debugging and development. Its repository is at: https://github.com/raspberrypi/ picotool In particular, it has the ability to extract the flash memory contents and write it to a UF2 file for distribution. This is handy for platforms using PicoMite BASIC, allowing a snapshot of the flash memory including saved BASIC programs, libraries and options. Like much of the other software, these tools have been updated to allow them to work with the RP2350 as well as the RP2040. Extra commands have been added to version 2.0.0 of picotool, allowing access to the OTP (one-time programming) and security features of the newer part. While there are instructions for compiling picotool (and some other software tools), this can require extra tools to be installed. We have found and used a separate project that provides compiled binaries at https:// github.com/raspberrypi/pico-sdktools/releases Summary Screen 5: a new project should be saved as a workspace to assist navigation. All the important files are found in the left-hand pane. siliconchip.com.au Australia's electronics magazine The Pico 2 appears to be better than the Pico in almost every way and is only slightly more expensive. As it also corrects the ADC erratum in the Pico, it is satisfying to be able to update the Pico Analyser to make use of this new part, although we don’t have any plans to update any other projects immediately. We have found the transition to the new board to be just about seamless, and look forward to using it in future projects. In recent news, the Pico 2 W has been released and we expect that using it should be similarly straightforward. SC March 2025  91