Adafruit 8×8 led matrix won't work on Photon

photon
Tags: #<Tag:0x00007fe22bd84e50>

#1

Hello all

I am doing a school project where I need to use the adafruit 8×8 led matrix to monitor the sensors’ measurements. But I am having trouble getting it to work using the built-in library. I used Adafruit_GFX_RK and Adafruit_LEDBackpack_RK in the Photon library and wired the matrix to the Photon microcontroller as instructed. It showed the code has been compiled successfully but the led matrix won’t work. Any idea or suggestion is much appreciated.

Best
Chunxu


#2

You are showing some example codes that come with the library but not what code you actually compiled.


#3

The reason it is not working is because for sure you are using the wrong class for the matrix8x8.

Have a look in the example matrix8x8.ino with the library.
This is what should be used to create the matrix object.
Adafruit_8x8matrix matrix = Adafruit_8x8matrix();

Then in setup
matrix.begin(0x70); // pass in the address

Then you write bitmaps or other GFX graphics (line, square, circle, etc.)


#4

Thanks for all the suggestions. A quick update, I used another led backpack library and it worked. But I am still not sure what was the problem.

And the next step for my project would be to display the sensor readings on the matrix. I am so new to the whole thing. Could someone tell me where to look at so I can have something, to begin with?

Best
Chunxu


#5

I made some small stuff with these driver-ICs (HT16K33), they are rated for 4.5V to 5.5V, your supply-voltage should be in that range. I experienced these ICs doing strange stuff (until not doing anything at all) at 3.3V. For the input (I2C-) voltage 3.3V worked fine even though it’s also out of the specs.