MODMYPI edited this page Sep 3, 2018 · 18 revisions

The PiOT Relay Board

Anyone who’s attempted to use a relay with a Raspberry Pi, or other microcontroller, will know that it’s not the easiest of tasks. It usually involves the integration of relay, diode, transistor and/or pull-up, pull-down resistors and fiddly jumpers. There’s also a number of issues centered around boot-chatter which can lead to unexpected behaviour. Cheap relays and relay boards can also be unreliable, varied in their specifications, and unpredictable in their typical current draw. When you’re using 230V mains, you really want to be sure that you can depend on the product you’re using, and it isn’t always that easy. Ultimately, relays and the Raspberry Pi has been a bit of a headache. Until now!

The PiOT (Pi of Things) Relay Board is designed to make it easy to integrate and use relays with the Raspberry Pi and other microcontrollers. No transistors, voltage dividers, diodes or jumpers; the PiOT relay board is designed to be a plug and plug relay solution for the Raspberry Pi. All these fiddly, and frankly not very fun, bits have been bundled into an on-board control PIC, making configuration faster, easier and safer. The PiOT relay board can be connected directly on top of the Pi, or via a GPIO ribbon cable, and also features mounting points for the Raspberry Pi Zero, giving instant plug and play access to four high power relays.

The PiOT relay board allows you to bond a GPIO pin to a relay with the touch of a button. No need to tie pins using resistors, and no need to re-wire the circuit or re-configure your jumpers when you want to change which GPIO pin fires which relay. Simply select your GPIO pin using the on-board tactile buttons and two-digit 7-segment display, and switch that pin high or low to fire your designated relay!

The on-board display can be configured to show the Pi's GPIO (also known as BCM) or Pin number system for GPIO/relay bonding, and also demonstrates visual feedback of the relay's on/off status for easy monitoring. The display can also be used to test relays before configuring them with your Pi, in addition to providing menu access for setting configuration. The PiOT relay board also features multiple innovative start-up modes designed to combat "chatter" on the GPIO which can lead to unexpected behaviour. Variable delayed start-up allows users to pause activation of the relays for a short period during boot, ensuring that GPIO pins are correctly set prior to use, or the alternative handshake mode utilises a specific pulse train to enable activation and de-activation of the relay board at the user's will. No more accidental switching of relays at boot!

The PiOT relay board uses a low current PWM (pulse width modulation) signal to significantly reduce the current required, ~100mA with all relays switched on, when compared to other relay boards. This means that relay boards can be stacked up to 5 high without requiring additional external power.

The PiOT relays are also compatible with both 3.3V and 5V, so you don’t need to worry about adjusting your input voltage depending on your microcontroller. Simply select your relay, switch your pin and the PiOT Relay Board will do the rest.

Want to know more about relays? Check out out Introduction to Relays here! Or, if you're ready to get started with your PiOT Relay Board, check the Installation Section!

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