Bi-Color LED Matrix HT16K33 LED Backpack Issue

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1

I’ve been working with Alex on this display, let me add some details…

We are working with the Adafruit bi-color LED matrix [1]. It uses the same i2c controller as the single color matrix [2]. I have code [3] that works fine with the single color display, but not with the bi-color. I’ve tried running the bi-color at both 3.3 and 5V. I can see that its registers are being written, but nothing lights up. A oscilloscope shows that the clock and data lines have signals on them.

Has anyone been successful at interfacing the bi-color LED matrix to a BeagleBone? How do you do it?

–Mark

[1] http://adafruit.com/products/902
[2] http://adafruit.com/products/872
[3] https://github.com/MarkAYoder/BeagleBoard-exercises/tree/master/i2c

2

Did you ever figure out how to make it work?

3

Yes. It turns out it’s a 5V device so you can’t drive it directly from the Beagle. Rather, a 3.3 to 5V level converter does the trick[1].

–Mark

[1] http://elinux.org/Adafruit:_Bicolor_LED_Square_Pixel_Matrix

4

Oh I see!
Can’t you just use P9.5? It supplies 5V right?
http://circuitco.com/support/index.php?title=Cape_Expansion_Headers

Also, did you use a C++ compiler to interface with the LEDs?

5

Yes, but you also need to shift the clock and data lines from 3.3 to 5V and back.

No, I just used plain old C.

–Mark

6

Oh okay, thank you!