Raspberry Pi Debug Probe: a plug-and-play debugging kit for $12
a few days ago the Raspberry Pi Foundation introduced a debugging probe, the Raspberry Pi debugging probe, which you can examine the code that runs on the microcontrollers.
In a post the Raspberry Pi Foundation announced that they decided to make this probe after noticing that people were using one Pico to debug programs running on another.
This is the first new product from the Raspberry Pi Foundation for 2023 and it comes at a time when the Foundation is striving to improve the availability of the Zero W, 3A+, and 2GB and 4GB versions of the Raspberry Pi 4, including limited supply due to component shortages that have lasted since the start of the pandemic. of coronavirus. The debug probe is a device that is supposed to make it easy to debug entire software on the Raspberry Pi Pico.
Built around the RP2040 microcontroller with "Picoprobe" firmware, This compact board offers a USB port to SWD (Serial Wire Debug) and UART (Universal Asynchronous Reception and Transmission) for debugging code running on a Raspberry Pi Pico or other Arm technology-based microcontrollers.
For those unfamiliar with the Raspberry Pi Pico, this is the Foundation's $4 Single Board Computer for Microcontroller Functions. On embedded computers of this type, there is often no display output, and in typical use, no operating system, making it difficult to monitor what you are doing or, more specifically, determine why you aren't doing it.
"Since we released the Raspberry Pi Pico, and our RP2040 microcontroller, in January 2021, people have been using one Pico to debug programs running on another," says Raspberry Pi co-creator Eben Upton in the blog post.
“Inspired by this trend, we are launching the Raspberry Pi Debug Probe, a comprehensive hardware debugging solution for RP2040-based Arm-based microcontrollers, priced at just $12,” he added. The Raspberry Pi Debug Probe is the third in-house designed board to incorporate the Raspberry Pi RP2040, a dual-core Arm Cortex-M0+ microcontroller with intelligent programmable input/output (PIO) blocks. The probe package includes a USB to SWD (Serial Wire Debug) bridge, a generic USB adapter, and cables to connect to a host computer and debug target.
The Arm SWD interface is a common way to take a look at the memory of an embedded Arm device and find out what it's doing.
In other words, it is the three-wire version of the traditional four- or five-wire JTAG interface. However, to use these SWD signals, you need a device to read them and translate them into something another computer can read and interpret, using software like FOSS OpenOCD or pyOCD. This device is called a debugging probe. Conveniently, the GPIO interface of a Raspberry Pi can pass SWD signals on some of its pins.
This means that one RPi can be used to debug another RPi. This even includes the Pico Pi which uses special firmware called Picoprobe.
It's quite a bit cheaper than a dedicated hardware debugging probe. But the problem is that you will still need to wire some circuitry, as described in this blog post. While versatile - you can also use SWD to download software onto an RPi Pico from another RPi, for example - it's not as easy, and if you want to use a larger and faster computer such as a PC or Mac, then you'll need to connect your Pi-based probe to it.
This is the goal of the new debugging probe. Plug one end into your Pi Pico and the other end into a free USB port, and you're done. It's a very low-end offering, but it should work, and it's $12.
For comparison, a professional tool like Segger's J-Link costs between $500 and $1000, and even an open source hardware device like the ORBtrace Mini costs more.
Also, the debug probe should be able to communicate with any embedded device that has an ARM Cortex-M3 interface and SWD, such as the Arduino Due, which is based on 32-bit Arm architecture.
Finally, it is worth mentioning that according to the organization's website, the Raspberry Pi Debug Probe is already available for $12.