WSAL20218 – Pico-Relay-B/en

Documentation notice: This technical documentation was independently rewritten from an archived supplier source. Check technical details and commands against the product version and manufacturer documentation before use.

Summary

The Waveshare Pico Relay B is an industrial 8-channel relay module with power-supply and photocoupler isolation. It provides a protected ABS enclosure with rail-mount support, breakout USB and BOOT pins, and status indication via PWR LED, RGB LED and passive buzzer.

Related products at JW Tech

WSAL20218 – Industrial 8-Channel Relay Module for Raspberry Pi Pico, Multi Protection

Technical overview

Operating voltage: 5 V; communication via Micro USB at 115200 baud.
Eight relays in form 1NO/1NC, contact rating up to 10 A / 250 V AC or 30 V DC.
Each relay is driven by its own GPIO: CH1–CH8 on GP21–GP14.
RGB LED on GP13, passive buzzer on GP6.
ABS enclosure supports rail mounting; USB and BOOTSEL are accessible from the enclosure.
Flashing firmware uses bootloader mode (hold BOOTSEL while plugging in USB).
C sample project is built with CMake; the resulting main.uf2 is copied to the RPI-RP2 drive.
MicroPython firmware files: rp2-pico-20210418-v1.15.uf2 and rp2-pcio2-20240809-v1.24.0.uf2 for Pico 2.
For Pico W: because the BOOT pad location differs, the bundled BOOT switch cannot enter flash mode.
TCP control commands via the built-in TCP server: 'Relay 1' through 'Relay 8', 'Relay ALL OFF', 'Relay ALL ON'.
Serial hex protocol: 01–08 toggle individual channels, 09 = all off, 0A = all on.

Commands and examples – verify before use:

01
02
03
04
05
06
07
08
09
0A
Relay 1
Relay 2
Relay 3
Relay 4
Relay 5
Relay 6
Relay 7
Relay 8
Relay ALL OFF
Relay ALL ON

Notes and version constraints

The source contains no information about certifications, warranty, or pricing; these must not be assumed.
Version sensitivity: the correct MicroPython firmware depends on the specific Pico variant (Pico vs. Pico 2).
Pico W requires manual configuration of WiFi settings (SSID, password, server IP, port) before compiling.
For first-time Arduino uploads, select the uf2 board first; if issues arise, a clean reinstall of the Arduino IDE plus manual cleanup of the AppData folder may be needed.
All command sequences should be verified against the current firmware version before production use.

Source and revision record

Pico Relay B - Waveshare Wiki
Source revision: 91368
Captured: 2026-09-02T03:33:06+00:00
SHA-256: 5026e16972ec97a79643bdc724f5de8ff5e57e672420613f26a3b075bf94aa6b