First Test of Arduino with Max7219 LED Driver and LTP2657 LED Matrix

I’ve been doing some more Arduino hacking, this time with my newly-arrived MAX7219 LED Driver circuit. Here’s what I have right now:

The circuit is very simple – The MAX7219 connects to Arduino on pin 2, 3 and 4, and I use the sample code in the Arduino wiki (http://www.arduino.cc/playground/LEDMatrix/Max7219). The LED Driver is connected to a little 7×5 segment display I picked up at HCS (A surplus electronic store in Sunnyvale) labelled the LTP2657AA. I had to reverse engineer the pins to figure out what goes where, but manage to connect up the digits to the ground (cathodes) of the LEDs in the segment, and the segments to the positive (anodes) terminals. With one transistor (10K) to keep the voltage levels okay and following the MAXIM data sheet I managed to get it all up and running.

For future reference, here’s the pin layout of the LTP2657AA, if the notches is at the bottom, bevels at the top, and held horizontally:

rows are anodes, cols are cathodes

LEFT

1 – green row 1
2 – red row 1
3 – green col a
4 – red col a
5 – green row 2
6 – red row 2
7 – green row 3
8 – red row 3
9 – green col c
10 – red col c
11 – green col d
12 – red col d
13 – green col b
14 – red col b

RIGHT

1 – red col f
2 – green col f
3 – red col d
4 – green col d
5 – red col e
6 – green col e
7 – red row 3
8 – green row 3
9 – red row 4
10 – green row 4
11 – red col g
12 – green col g
13 – red row 5
14 – green row 5

Its quite a nice little matrix, duo color (although it only displays one at a time), and for $2 i cant complain!

so, now its all about building a sweet project.

4 Comments

  1. Anonymous says:

    hey,

    will you post the code you’re using?
    That would be great.

    J

  2. oskay says:

    Hey thanks– I picked one of these up at HSC and was trying to find the datasheet… but Google brought me to your page instead. So thank you– you just made my life a little easier!

  3. Ronald says:

    Thank you for pushing me on. I enjoyed your writeup and was able to find a datasheet at datasheet archives.

    http://www.datasheetarchive.com/preview/2061499.html

  4. Ronald says:

    p.s. Also the datasheet says you can run Green and Orange together to get Yellow. (FYI)