Adafruit 1270 LED Display

Adafruit’s 1.2 inch 7-segment LED display with backpack using a HT16K33 chip is a nice piece of hardware. It’s bright, large enough to be read from a fair distance, and easy to use.

I worked by way though the example provided by Adafruit and then through the required files to figure out how this display worked via python.
The display has 4 digits, 2 colons, and 1 dot arranged as: colon, digit, digit, colon, digit, dot, digit.
The digits and the middle colon can be addressed via the SevenSegment class.
The first colon and the dot can be addressed manually via the HT16K33 class using the set_led method.

The HT16K33 chip can support 128 LEDs.
The display here only has 33 LEDs total but the center colon’s 2 LEDs are tied together thus using only 32.

The LEDs on the display are mapped to the HT16K33 as follows:

  • Digit 1 = 0-6
  • Digit 2 = 16-22
  • Digit 3 = 48-54
  • Digit 4 = 64-70
  • Center colon = 33
  • Left colon, top dot = 34
  • Left colon, bottom dot = 35
  • Dot (between digits 3 and 4) = 36

The LEDs on each digit are arranged in the following sequence:

  1. top
  2. top right
  3. bottom right
  4. bottom
  5. bottom left
  6. top left
  7. center



Adafruit’s product page
Adafruit Learn: Large Thermometer and Clock
Adafruit Learn: LED backpack Displays on Pi
Adafruit Learn: LED Backpack Displays

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