Switching a real 240V load from a microcontroller is where a lot of student automation projects stall. A Raspberry Pi Pico can toggle a GPIO pin all day, but wiring that pin to a mains-powered pump, light, or motor safely means relays, optoisolation, and screw terminals you can actually trust. Olimex's new PICO-EVB carrier hands you all of that on one board, so your thesis or classroom demo can control the real world instead of just blinking an LED.
What the PICO-EVB actually is
The PICO-EVB is a carrier board that accepts any Pico-format board: a Raspberry Pi Pico, Pico 2, Pico W, Pico 2 W, or Olimex's own PICO30. You drop the Pico into 0.1"-spaced female headers, and the carrier breaks its pins out to four heavy-duty relays and four isolated inputs. For most Picos you'll need to solder male headers on first, so keep a soldering iron handy. Founder Tsvetan Usunov pitches it plainly: plug in a Pico and "you're ready to switch loads and read signals."
The specs that matter
Each of the four relays is rated 15A at 240VAC, with both normally-open and normally-closed contacts wired to screw terminals. The four optoisolated inputs accept either 3.3-30VDC or 110-220VAC, so you can read industrial sensors without frying your Pico. Every relay and input gets its own status LED for at-a-glance debugging. There's a UEXT connector for solderless I2C, SPI, or UART sensor expansion, and power can come from the Pico, a USB-C port, or a screw terminal. The board (everything except the Pico) is rated for a -45 to 85C industrial temperature range.
Build it yourself
At around 17 dollars (roughly PHP 950) plus a Pico you may already own, this is an affordable jump into real programmable-logic-controller territory. Olimex ships Arduino and MicroPython examples for reading inputs and driving relays, plus a MicroPython web-server sketch that lets a Pico W toggle outputs from any browser, and an ESPHome YAML file for dropping the board straight into Home Assistant. Design files sit under the CERN Open Hardware License v2 and the code under MIT, both on GitHub. Grab the board and source from the Hackster writeup and start with the relay example before you wire anything to mains.
Originally published on blog.circuit.rocks.
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