6.1. Microcontroller

The 3pi+ 2040 features an integrated Raspberry Pi RP2040 microcontroller, a 32-bit dual-core Arm Cortex-M0+ processor with 264 kB of RAM, clocked with a 12 MHz crystal. This is the same microcontroller and crystal frequency used on the Raspberry Pi Pico. The RP2040 typically runs with a default system clock speed of 125 MHz, although it is rated for a maximum of 133 MHz and can sometimes be pushed even higher.

The control board includes a 16-megabyte (128-megabit) flash memory chip for program storage (non-volatile memory), and this comes preloaded with a MicroPython interpreter and example programs to help you get started quickly. For more information about programming the 3pi+ 2040 in Python, see Section 5.

The RP2040 has built-in USB support, and the control board has a USB Type-C connector that can be used to connect it to a computer (cable not included). This USB connection can be used to transmit and receive data and program the board over USB. The USB connection can also provide power for the microcontroller and most of the other hardware on the board (but not motor power); see Section 6.7 for more details.

The board also exposes the RP2040’s Serial Wire Debug (SWD) interface, which can be used to interactively debug a program running on the 3pi+ or to program the flash memory as an alternative to using USB. The debug port consists of two signals, SWDIO and SWCLK, along with a ground pin; these pins are labeled on the bottom side of the control board, and SWCLK is indicated with a small white triangle on the top side. To use the SWD interface with a standard desktop or laptop computer, you will need an external device, such as a Raspberry Pi Debug Probe or a Raspberry Pi Pico running the Picoprobe firmware.