If you are interested in learning how to control RGB LEDs with the Raspberry Pi (RBPi) single board computer, Blinkt! provides a simple way to interface. Blinkt! is a strip of eight superbright RGB LED lights that you can connect to the RBPi without wires, so it is an easy way to start. Blinkt! Has a female connector that matches the male GPIO connector on the RBPi, and that allows the tiny LED board to sit atop the RBPi.
The RBPi can individually control each of the eight APA102 RGB LEDs on the Blinkt! board individually, so you can consider them as matrix of 1×8 pixels. The footprint of the board is tiny enough to allow it sit directly on top of the RBPi and the pair fits inside most of the Pi cases. Although the RBPi controls the eight LEDs with PWM, it does not interfere with the SBC’s PWM audio. Blinkt! comes fully assembled and is compatible with RBPi models 3, 2, B+, A+, Z, and ZW. Pimoroni, the manufacturers of Blinkt!, also provide a Python library for the users.
Combining Python programming and Blinkt! with the RBPi is a great way of understanding how RGB LEDs work and how a computer program controls their operation.
If you are using the RBPi3 for this project, it will already have the male GPIO on the board. However, the RBPiZ and RBPiZW may not have the connector, which means you may need to solder the connector to the board. You need to be careful when plugging the Blinkt! board onto the RBPi taking care to orient it in the right way. The Blinkt! board has rounded corners on one of its side, and this side should face the outside of the RBPi. Once you align the boards properly, push the Blinkt! board in and it should fit snugly on the RBPi.
To make the RBPi control the LEDs on the Blinkt!, it will need to have the right code. The best way to begin is to update the Operating System of the RBPi to the latest Raspbian. Once you have done this, and the RBPi is running, connect it up to the Internet and open the terminal on the RBPi screen.
Typing the code “curl https://get.pimoroni.com/blinkt | bash” without the quotes, should allow the RBPi to download the necessary Python libraries from the Pimoroni website. Now you can use the Python 3 IDLE code editor to use the library to write the Python program and control the LEDs.
While writing the Python program, you will need to begin by importing the Blinkt! library you had downloaded in the first step. Each LED is termed as a pixel so the parameter “set_pixel” allows you to address a specific LED, while “set_brightness” allows setting its brightness. The command “show” turns on the specific LED, and “clear” turns it off.
Even though the LEDs are numbered as 1 to 8 on the board, the program addresses them as 0 through 7. Therefore, the program can pick a light and tell it the color it needs to be, its brightness, and whether it should turn it on or off.