HT16K33, Breakout, Drive 8 alphanumeric displays

[shine]

Hi!

Just ordered some HT16K33-Breakout-board to test drive 8 alphanumeric displays.

Is there any reason why your alphanumeric breakout board utilizing this chip only supports 4-digits? I think it should drive 8 as well or is there any reason why it would not work? Maybe not enough current for 8 digits?

Thanks and regards from Germany,
Jan

[adafruit_support_rick]

Yes, the HT16K33 should be able to drive 8 alphanumerics, but we only designed for 4.

[disasterarea]

I was wondering the same thing - the driver has eight cathode pins so adding four more alphas should be pretty simple.

What kind of changes would need to be made to the library to support the extra four digits?

[adafruit_support_rick]

No idea. The display buffer is already 8 characters long, so it might just work (probably not, but we can hope...)

[disasterarea]

I had a look at the code last night. Each segment needs a 16 bit mask, so the code takes the incoming characters from a look-up table and splits them into upper and lower nybbles before blasting them out the I2C bus. I think you will need to make the displayBuffer[8] into displayBuffer[16], and likewise double the displaySplit[] array size. Since the display has no memory on its own, the library populates the displayBuffer[] array, then when you call display.writeDisplay() it sends the whole buffer contents out to the HT16K33. I'll try it and let you know.

[linux_works]

any update?

I'm thinking of trying to mod the chip backpack to 8chars or the alpha 4char backpack to add 4 more chars.

if someone has done this, please post. else, I'll give it a try and report back.

4 chars is nice. there are times I'd like to have 8 chars, though. LCD is ok, but overused and now 'boring'. old classic LED is becoming popular again and for good reason, too (size and contrast; hard to find an LCD that can be seen from a distance like the half inch LED alphas).

[Allan3026]

I know this is an old post but I hd the same question. How to drive 8 digits with 1 breakout.
After experimenting, this is how I made it work.
In the "Adafruit _LEDbackpack" "CPP" file, i changed 2 numbers on the 3rd line from the bottom. Both originally said D > 4 and now say D > 8. Just edit the file with notepad and save.
Now I can use all 8 cathodes to give 8 digit display.