Raspberry Pi Edge Class Devices Hardware Review

The Raspberry Pi Pico is the MCU development board that uses the chip RP2040, designed by Raspberry Pi in 2019.

It is intended as a low-cost, low-power device with big computational possibilities and connectivity features. This device is intended to work with constrained power sources, mainly battery-powered. The MCU integrates all features, including 6 banks of RAM, an interrupt controller, DMA, timers, oscillators, I/O, voltage regulator and ROM in a single enclosure.
A compact, 7x7mm chip exposes 26 GPIOs and is one of the most affordable MCUs, estimated at 4 USD/piece only.

Currently, there are 2 types of development boards available: Raspberry Pi Pico and Raspberry Pico W. The last one provides wireless connectivity. It is also possible to have just MCUs (RP2040) as chips to be soldered; thus, third-party development boards are available in the market. A genuine RPi Pico W development board is present in the figure 1.
With a built-in voltage regulator, the input voltage range is wide and starts from 1.8V up to 5.5V.

The CPU is an ARM Cortex-M0+ (double core) running up to 133 MHz (scalable). It supports DMA. There is no FPU, however. A Nested Vector Interrupt Controller is also present, along with a 24-bit timer. CPU and NIC can be put into the very low power mode.

RPI Picos have 264kB of internal RAM (SRAM) and 2MB of built-in QSPI flash with the capability for an extension with external one up to 16MB. RAM uses DMA to perform CPU-less transfers.
There is a 16kB ROM that contains bootloaders, USB mass storage UF2 support and utility libraries such as FPU implementation.

Only the Pico W series includes a built-in radio that is 802.11n (2.4 GHz WiFi) and Bluetooth 5.2.
IoT-specific protocols are supported only with external modules.

The Pico MCU includes a rich set of peripheral interfaces:

• 26 multipurpose GPIO inputs/outputs,
• 2xUART,
• 2xSPI,
• 2xI2C,
• 15 PWM channels,
• 4xADC 12-bit (500ksps) converters where only 3 are usable, with a temperature sensor (for compensation),
• 8 programmable state machines,
• USB 1.1 controller (PHY) with HOST and DEV.