Hi all,
My first post. Please be gentle haha.
I've tried researching, but haven't had any specific luck.
What I'm trying to do is illuminate 10x RGB leds using an arduino nano. I obviously do not want to tie up 30 pins (which the arduino boards don't have anyway!) for 10 leds. I've looked into led matrices which use a MAX7219 led driver. There are plenty of examples where 8x8 dot matrices have been made.
However, I'm curious whether I can use the same MAX7219 chip (as it only requires a few input connections) to custom make a 10x3 matrix? I.e 10 leds with RGB...
I don't want a mix of red, green or blue for a single led, but I want either of the colours on their own. That way, a single led will be either red, green or blue, but not a combination between.
Any thoughts or examples?
Thanks.
Sure, wire them up like this, then send data with just 1 bit high for each RGB to turn on 1 color.
Some use the LED.h library, I prefer to use SPI.h and just send SPI.transfer() commands.
You need to send 5 command in setup() to tell the chip how many columns, the brightness, no decode mode, normal mode (vs shutdown), and not display test mode:
digitalWrite (ssPin, LOW);
SPI.transfer (registerAddress);
SPI.transfer (dataToSend);
digitalWrite (ssPin, HIGH);
Then use the same to send data to registers 1 to 8, each register will be one digit or column.
Sending 0b00100001 would turn on upper Blue and lower Green in a column for example.
00(100)(001) you can see how the bits represent the two groups of LEDs in a column with the two upper bits not used.
The datasheet for the MAX7219, page 8, shows the data register is actually set up as DP-A-B-C-D-E-F-G, so you may want to connect to B-C-D-E-F-G to use the lower 6 bits like I did above.
Thank you,
I will experiment this weekend and will post back 
