If you only need the smallest of Raspberry Pi chips, but you need a lot of them, you can now buy the gang's RP2040 microcontrollers directly from the
farm supplier in lots of 500 or 3,400.
Because the Raspberry Pi range is so cheap, people use lots of them – even in places where a complete Linux computer is arguably overkill. That's probably why, this time last year, the Raspberry Pi Foundation launched the Raspberry Pi Pico, a $4 device based around the RP2040 microcontroller – its first in-house CPU design.
The end-user version of the Pi Pico is a tiny PCB containing the RP2040 system-on-a-chip (SoC) and 2 MB of flash memory. (The board is a hair over 2×5cm, so only slightly bigger than an old-style DIP chip such as a Z80.) The RP2040 is still an ARM, but a tiny one: a dual-core 133 MHz Cortex M0+, plus 264 kB of RAM.