Since we're using I2C for the shield and real time clock, hookup is fairly straightforward. Don't forget, I2C allows you to use multiple devices on two shared pins, perfect for when you don't have a lot of pins like the Trinket!

1) Assemble the RGB LCD Shield per this tutorial
2) Assemble the DS1307 clock per this tutorial
3) Solder supplied male headers to Trinket


All components are hooked to 5 volts and ground. Note the ground pin used for the shield (the ground pin next to the 5 volt pin will NOT work, it isn't connected!)

Hookup of the display is easier with some male-female extension wires especially if the shield has male headers already soldered on. For breadboarding this allows the display to just plug in.
The clock and display are connected to Pin 0 and Pin 2 on Trinket. Pin 0 is the I2c data line (SDA). Pin 2 is the I2C clock line (SCL). Both the display and the clock can share this bus as they each have a different address assigned during manufacture. The sharing of the bus saves pins in a Trinket project. Use of the buttons on the LCD shield is also through the I2C bus, again saving pins.

If an LCD display with I2C backpack were substituted for the shield, other data pins on Trinket could be used for buttons. Use of an I2C expander chip such as the MCP23008 or MCP23017 to gain an additional 8 or 16 pins respectively.

You can easily fit the parts for permanent mounting on a half perma-proto board, perhaps a quarter perma-proto board with some moving of parts. If you decide on a permanent mount, I suggest use of female header to mount the Trinket, perhaps even the clock module, in case the part has issues you can quickly swap it out.

This guide was first published on Jan 27, 2014. It was last updated on Jan 27, 2014.

This page (Hook-up) was last updated on May 08, 2021.

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