Parts

To build this project you'll need the following parts:

• INA219 current sensor breakout.
• Pro Trinket 5V or 3.3V.  Unfortunately the normal Trinket doesn't have enough space to run the code for this project, so stick with the Pro Trinket or even an Adafruit Metro 328, Arduino Uno, Leonardo, or similar board.
• Appropriate USB cable for your microcontroller. For micro B you can use this one.
• Monochrome 128x32 I2C OLED display.  You could use a larger OLED like the 128x64 display too (but only the top half will be used unless you modify the project code).  An SPI or even color OLED display would work too if you modify the project code to use the appropriate display driver library.
• Breadboard and hookup wires to connect all the components.
• Soldering tools to assemble the breakout boards by soldering on headers, etc.

Once you have all the parts make sure they are assembled by following each of their guides.  Here's a handy list of guides to follow:

• INA219 Guide
• Pro Trinket Guide
• Monochrome OLED Guide

Wiring

To wire up the components you just need to connect their power, ground, and I2C pins.  In addition the OLED will need a digital pin connected to its reset pin.  Make the connections as follows:

• Pro Trinket 3.3V or 5V power to INA219 VCC and OLED VIN.
• Pro Trinket ground (G) to INA219 ground (GND) and OLED ground (GND).
• Pro Trinket I2C SCL (A5) to INA219 SCL and OLED SCL.
• Pro Trinket I2C SDA (A4) to INA219 SDA and OLED SDA.
• Pro Trinket digital 4 to OLED RST.

The diagram below shows the wiring connections too.  Notice the OLED is rotated upside down so all the components fit on a half-size breadboard.

Once the components are wired together continue on to learn how to load the sketch and use the tool.