With the introduction of the RP2040, the Raspberry Pi Foundation set its sights on the microcontroller market. The second revision of the chip takes the well-liked features of the first version and expands them to simplify the life of designers.

In addition to specification improvements, the new Raspberry Pi microcontroller permits developers to select between ARM Cortex M-33 and RISC/V-based cores at start-up. When combined with the high-quality documentation and the variety of SDKs, this microcontroller is ideally suited for applications where development manpower needs to be minimised.

Hazard 3 provides an alternative to ARM

Most microcontrollers implement either an ARM or a RISC/V-based design. In the case of the RP2350, cores can be combined—at start-up, designers select which of the cores to use. One interesting aspect is that the RISC/V cores are fully open-source; the documentation lives on GitHub under the URL https://github.com/Wren6991/Hazard3.

No special regimen has been found that enables the use of all four cores in parallel. Thus, the RP2350 is a high-performance dual-core microcontroller.

More memory and new case options increase designer flexibility

The first-generation Raspberry Pi microcontroller required external flash memory to store the code that the MCU was to execute. Four different versions of the RP2350 exist.

The SKUs RP2354A and RP2354B have 2 MB of flash on the chip, while RP2350A and RP2350B continue to use external flash memory. An increase in the RAM size aids the execution of artificial intelligence models. The new version of the Raspberry Pi microcontroller has 520KB of memory, while the predecessor had to make do with 260KB. Finally, the larger QFN versions provide a total of up to 48 GPIO pins using the pin layout shown.

Next-generation PIO units simplify data handling

Handling large amounts of (streaming) data on microcontrollers has always been an interesting challenge. The RP2040 ventured into FPGA territory via a peripheral called PIO. On the RP2350, the capabilities of the IO engine are greatly improved. An example of this HSTX unit's compute prowess is found at https://github.com/Wren6991/PicoDVI, where the microcontroller creates DVI output. Furthermore, various other examples of data processing are available. The RP2350’s PIO engine can often avoid an FPGA, lowering total design costs.

In addition to that, more hardware-accelerated peripheral devices are provided on the new version of the chip. In the announcement, the following list of hardware-accelerated units can be found:

  • 2 × UART
  • 2 × SPI controllers
  • 2 × I2C controllers
  • 24 × PWM channels
  • 4/8 x ADC channels
  • 1 × USB 1.1 controller and PHY, with host and device support
  • 12 × PIO state machines

Raspberry Pi Pico 2 for easy evaluation

The Raspberry Pi Foundation also provides a variety of evaluation boards in the well-known Raspberry Pi Pico form factor. Searching for the SKU SC1631 leads to the classic Raspberry Pi Pico 2. It provides the RP2350 microcontroller along with flash memory and a commanding device, thereby permitting an easy start-up. Should a wireless module be required, the SC1633 SKU can be purchased. It provides the Raspberry Pi Pico 2W, which combines the microcontroller with a wireless module.

The Infineon CYW43439 supports all recent communication standards. In the datasheet, the following description is made available:

  • WiFi 4 (802.11n), Single-band (2.4 GHz)
  • WPA3
  • SoftAP (Up to 4 clients) 
  • Bluetooth 5.2
  • Support for Bluetooth LE Central and Peripheral roles
  • Support for Bluetooth Classic

Easy to program in Python

Even though the RP2350 comes with a complete C SDK, Python developers can also program the controller. The URL https://micropython.org/download/?mcu=rp2350 provides a Micropython runtime that can be deployed using the embedded bootloader known from the first generation. In addition, https://circuitpython.org/board/adafruit_metro_rp2350/ provides a version of CircuitPython for the RP2350.

Conclusion

The RP2350 and its accompanying evaluation boards improve the Raspberry Pi microcontroller design to provide additional computing power. Especially when working on a design where man hours are at a premium, the RP2350’s excellent documentation makes it an excellent choice.