The Raspberry Pi Debug Probe provides both a processor serial debug interface (by default this is the ARM Serial Wire Debug interface) and an industry-standard UART interface. Both interfaces use a 3-pin debug connector, as specified in the Raspberry Pi 3-pin debug connector specification.
The Raspberry Pi Debug Probe is provided as a kit, containing the probe hardware in a plastic case, and a set of cables: a USB cable, and three different types of debug cable to cover the vast majority of use cases.
While it has been designed primarily for use with Raspberry Pi debug targets, the Debug Probe provides standard CMSIS-DAP debug and UART interfaces over USB; it can therefore be used to debug other targets, or simply as a cost-effective USB-to-UART cable.
The Raspberry Pi Debug Probe is based on the Raspberry Pi Pico hardware design and runs the open-source Raspberry Pi Picoprobe software [https://github.com/raspberrypi/picoprobe]. Updating the firmware is accomplished in the same way as on a Raspberry Pi Pico, so it is straightforward to keep the unit up to date with the latest Picoprobe firmware, or to use a custom firmware.