Need a little help understanding the 8x8 led matrix bytes.

Other Hardware LEDs and Multiplexing
1

I've been playing around with 3x 8x8 matrix leds running on max7219's
My name tag :wink: Was bored, had to do something fun ;) new name sign for meetings etc. - YouTube

Anyway.. I want to know more about the forming of these bytes.
Clearly i have both letters and symbols, and found a online java script that can
convert symbols i "draw" into bytes for me..

However, when i look at the definition in my code, i fail to understand what the rows define.

Example, the letter/number 1 can be written like this

3, 8, B01000010, B01111111, B01000000, B00000000, B00000000

B01000010,
B01111111,
B01000000,
B00000000,
B00000000

I cannot see the number 1 form like this.

smiley face like this

8, 8, B00111100, B01000010, B10010101, B10100001, B10100001, B10010101, B01000010, B00111100

I can see the smiley form like this.

B00111100,
B01000010,
B10010101,
B10100001,
B10100001,
B10010101,
B01000010,
B00111100

Question 1:
What does 3, 8, in 1 and 8, 8, in smiley face define?
I'm guessing the second row is the number of leds across or something.

Question 2:
Why does 1 only need 5 rows of 1/0's while the smiley need 8?

Martin.

2

The bytes define the LEDs on (1) and off (0).

You say you cannot visualise the number 1 in the first example? Try turning the example there counter-clockwise 90 degrees and you will see something like this:
1
1
1111

which is a number 1 (lying on its side). Why this orientation? Because you want to scroll the digits in your display from, say, right to left, across all the LED matrices and that's the orientation each matrix needs to make them look correct when all the matrices are lined up! (Sounds far more complicated than it is).

The numbers 3,8 or whatever usually define the width and height of each character but as I don't know the structure of your particular layout this is only an (educated) guess.

It's a pity I have not yet done my video on LED matrices - I planned to do it weeks ago but life gets in the way as we make plans! You might get some benefit at looking at video #23 - it describes a similar custom character layout albeit for an LCD display - but the principle is quite similar. Perhaps the light bulb will then go on for you.

If you subscribe to my channel you will get notified when I get round to doing the LED matrix video (could be as soon as over the Easter break). And not a JavaScript library in sight.

3

It would help if you use monospaced fonts.

4

I didn't realize they where on the side.
But now you say it, yes got it :wink:

That makes a lot more sense