This is the magic sauce in our 7-segment and matrix backpacks, now
available in breadboard-friendly breakout board format. The HT16K33 is
a neat little chip that has the ability to drive a multiplexed 16x8
matrix (that's 128 individual LEDs). The communication protocol is I2C
so it uses only 2 pins, and you can have up to 8 selectable I2C
addresses so thats a total of 8 matrices, each one controlling 16x8
LEDs for 1024 total LEDs.
Unlike our LED matrix/segment backpacks, this breakout does not have
holes for an existing LED module. Instead, we break out all 16 anodes
and 8 cathodes as well as the I2C and power pins. You'll need to wire
up the anodes and cathodes by checking out your matrix datasheet and
lining up the pins. Wire up any matrix you want and use our handy
library to write to the display however you wish. Note that the driver
can turn LEDs on and off but does not have the ability to individually
PWM dim them. This chip is rock solid, has Arduino & Pi example code
written for it and is easy to use.
The chip supports also reading a 3x13 keypad matrix but we do not
have example code for it in our library, check the datasheet for more
details about the keypad functionality
* Arduino example code 
* Pi example code 
* 35.77mm / 1.4" x 20.37mm / 0.8" x 4.03mm / 0.15"