Addressable RGB and RGBW LEDs like the famous WS2812B allow engineers to apply fantastic lighting effects on a limited budget. We explored this interesting protocol in some detail, but if you want to get things "lit," you can use the Adafruit NeoPixel library.
The NeoPixel library works well on Arduino and Adafruit boards, but what about the humble ATtiny85? Can this little chip run a bank of programmable LEDs by itself? The short answer is "yes," however, you'll need to make a few changes to get your ATtiny85 working properly.
Programming ATtiny85 RGB LED with Arduino
To get started, follow these steps:
1. Install the Adafruit NeoPixel library on the Arduino IDE, which is generally a matter of performing a search and installation via the Library Manager (through the menus or Ctrl + Shift + I)
2. Load an included example—we'll use 'strandtest' here—customizing options like the number of LEDs and which pin actually controls the chain of RGB LED modules
3. For the ATtiny85, set up the Arduino IDE (if you haven't already). Note that the chip's physical pins won't be numbered in the same way as they are in the Arduino IDE, so use this diagram for reference. If you only need one pin for LED control, Arduino IDE pin 0 (physical pin 5) is in the opposite corner of the chip's dot
4. Under 'Tools,' set the board to 'ATtiny25/45/85,' and the processor to ATtiny85
5. Select 'Internal 8 MHz' for the clock speed, as this library doesn't work at its factory settings
6. With the ATtiny85 and programmer connected, hit 'Burn Bootloader' to instruct the chip to run at this speed
A 16 MHz clock may also work, but we did not include one in our testing. Also note that depending on which LEDs you use, you may have to change some other options.
Upload and Go!
Upload the modified example code using a programmer. Connect your power and ground leads to the voltage supply and connect the signal input to the pin you assigned on the ATtiny85. With everything correctly connected, you'll see a variety of changing colors and have an extremely compact setup to control one or more addressable LEDs.
ATtiny85 Programming in PlatformIO
If you're using PlatformIO, as introduced here using Visual Studio Code, you can also program the ATtiny85 using this IDE. While I won't go through a step-by-step tutorial on the subject, you can review a basic piece of example code that works with it. In order to run the code, you'll need the proper library and the ATtiny85 needs to be set to run 8 MHz. I used the Arduino IDE to set the clock speed.
Finally, modify the platformio.ini file to suit your chip. You can see the configuration that worked for me in the image below:
