Control 8 relays with the Raspberry Pi Pico using PicoRelay8 or Pico-Relay-B

8086 Consultancy’s PicoRelay8 is a baseboard for the Raspberry Pi Pico (W) board equipped with eight 28V DC / 10A Normally Open relays that be used for all sorts of automation projects, while Waveshare Pico-Relay-B also supports eight relays with both DC and AC loads and comes with some extra features.

PicoRelay8

Raspberry Pi Pico 8-relay board

PicoRelay8 board specifications:

  • Supported MCU board – Raspberry Pi Pico or Pi Pico W, and it may also work with “mostly” compatible boards such as the Banana Pi BPI-Pico-RP2040 or BPI-PicoW-S3, WeAct RP2040, and others as long as all GPIO used on the PicoRelay8 are exposed on the same pins.
  • Relays
    • 8x HF3FF/005-1HST relays rated for 28V DC/10A, as well as 10A/250V AC and 15A/125V AC, but the board is not designed to get power from the mains (safety-wise), so it’s only really suitable for DC loads
    • Each relay has a 2-pin terminal block attached to it.
    • GPIO high = close the relay to turn on the device attached to it, GPIO low = open the relay
  • Power Supply – 5V/500mA with the USB port on the Raspberry Pi Pico board or alternatives; The overall system can consume up to 500mA if all relays are switched at the same time, so make sure you use a properly sized power supply or ensure all relays can not be triggered at the same time.
  • Dimensions – TBD

PicoRelay8

There’s no sample code, but it’s now really needed since the user would just need to toggle GPIOs in the code. The PicoRelay8 is sold on Tindie for $18.80 plus shipping. But our European friends won’t be able to purchase the board on Tindie as UK-based 8086 Consultancy explains that “Due to the 1st July 2021 EU VAT changes and limitations to the Tindie system I’m currently not shipping to the EU”. The PicoRelay8 may eventually be available from other distributors in due time like some other products from the company.

Waveshare Pico-Relay-B

Waveshare Pico Relay B with Raspberry Pi Pico board
Waveshare Pico-Relay-B fitted with a Raspberry Pi Pico board

But while researching the topic, I also found an alternative board with similar features: Waveshare Pico-Relay-B described as an “industrial 8-channel relay module for Raspberry Pi Pico with multi- protection”.  The PCB comes with photocoupler isolation that allows it to work with up to 220V AC/10A appliances besides DC ones up to 30V/10A, as well as a few extra features such as a buzzer, two buttons, an RGB LED, and a micro USB port to control the GPIOs over USB. A 2-pin terminal is used to power the board, and the company also offers an enclosure.

Raspberry Pi Pico 8-Relay Controller with enclosure

A wiki is provided showing more hardware details as well as code samples and instructions to get started with C/C++ or MicroPython on the Raspberry Pi Pico. Github user longmover also wrote a MicroPython program to integrate the Pico-Relay-B with Home Assistant over WiFi (MQTT).

Waveshare is selling the Pico-Relay-B on its own store for $18.99 with the enclosure, but no Raspberry Pi Pico. Alternatively, you’ll also find it on Amazon US or Aliexpress for $26-$29 including shipping, as well as various distributors.

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2 Comments
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Willy
1 year ago

Interesting, it could be better than relying on proprietary controllers like I had to do for our lab. Among the interesting possibilities I’m seeing the option of saving the current setup to the eeprom so that upon reset the outputs are not lost. Maybe it’s possible here, maybe not. This would require external latches to make sure the chip doesn’t go high-Z during reset.

Also I’m seeing that it’s missing one or two extra rows of GPIOs (possibly just doubling the existing ones) to ease connection of extra buttons, leds, etc.

Phil Barrett
1 year ago

As to shipping from USA to the EU or UK from Tindie. Just do it. In your shipping software (I use Stamps.com), fill out the customs form and include the HS Tariff number (look it up, pretty easy). Make the customer pay VAT/Customs duty on their end. I’ve shipped several hundred and only one came back because the customer refused to pay the VAT. Yeah, Tindie could do a better job and they really need to handle US sales tax. If there was something better, I’d go with them.

Khadas VIM4 SBC