F.A.Q.

I want to use these modules with other non-Arduino, how can I port the code?

The best way to get up and running is to read the HT16K33 driver datasheet available at http://learn.adafruit.com/adafruit-led-backpack/downloads - the backpacks all use this chip to do all the LED driving. You can cross-reference this document with the Arduino library code to adapt it to your platform. Any microcontroller that has I2C host support should be able to drive the backpacks but we only provide Arduino example code at this time

I'd like to use these backpacks with Python / Linux (e.g. a Raspberry Pi)

You're in luck! We have a full tutorial here that covers using the 7-segment and 8x8 matrices on a Pi with Python code -> http://learn.adafruit.com/matrix-7-segment-led-backpack-with-the-raspberry-pi

I am having strange problems when combining Adafruit Motor Shield/Servo Shield (PCA9685 based) with the Adafruit LED Matrix/7Seg Backpacks

We are not sure why this occurs but there is an address collision even though the address are different! Set the backpacks to address 0x71 or anything other than the default 0x70 to make the issue go away

What is the current draw of the backpacks?

It depends on how many LEDs you have lit at once!

But a rough estimation is 20 milliamps per segment. Note that segments are multiplexed per row so that means

  • 8x8 Mono Matrix (8 rows)= 8 x 20mA = 160mA max
  • 7-segment backpacks (7 segments + 1 dot) = 8 x 20mA = 160 mA
  • Alphanumeric (14 segments) = 14 x 20mA = 280mA
  • Bi-color 8x8 and 8x16 matrix (16 rows) = 8 x 16 = 320mA

But again, this is maximum and assumes all digits and all segments are lit up! Your average use may be 1/10 to 1/2 of this amount

This guide was first published on Jul 29, 2012. It was last updated on Oct 19, 2018. This page (F.A.Q.) was last updated on Jun 17, 2018.