Suggested Reading
If you aren’t familiar with the Qwiic system, we recommend reading here for an overview.
We would also recommend taking a look at the following tutorials if you aren’t familiar with them.
Hardware Overview
Power
There are two separate power systems on the Quad Relay: a 5V system that powers the relays and a 3.3V system
that powers the on board ATtiny84A and interfaces with a microcontroller through the four pin header or Qwiic
connector.
The on board barrel jack takes a power source in a range of
7-15V
. It regulates the voltage and supplies power to
the 5V power system of the relays. If your wall adapter or power source is at 5 volts like our 5V/2A Wall adapter
then you can close the jumper on the underside of the product labeled
5V Wall Adapter
(see
Jumpers
section
below), and this will allow you to sidestep the on board regulator to power the 5V system directly. If you decide to
go with a higher voltage wall adapter, be cognizant that the voltage regulator will start to heat up. With all the relay
channels turned on the Quad Relay will pull ~250mA of current and at 9 Volts, that’s 2.25 Watts of power
(mathematical!). Over time the regulator will get hot, but will remain functional. I suggest that if you expect to have
all relay channels on for extended periods of time, that you go with a 5V power supply.
Asynchronous serial communication concepts: packets,
signal levels, baud rates, UARTs and more!
An introduction to I2C, one of the main embedded
communications protocols in use today.
