Driver for a 8x8 RGB LED Display

[computer]

Hi,

What is the best way to control an 8x8 RGB matrix such as this?

I'd like PWM of each LED, so I'm guessing something like the MAX6960 - but I can't see how to connect it up for an RGB display even though it says it is possible. Preferably would like to keep to SO or larger components but will go smaller if needbe.

Any suggestions for controllers / explanations of how to connect them is great.

computer

 

[justDIY]

the hard part is the software, the hardware is rather easy - just consider it a 24x8 array and wire accordingly. using tristate shift registers with (global enable pin) to drive the columns will let you do pwm somewhat in hardware, or you could do time domain division doing the pwm in software.

the best way to control that matrix would be the prefab controller they sell for it - plug and play! this page contains a schematic, detailing their driver method, see - shift registers!

https://www.sparkfun.com/commerce/product_info.php?products_id=760

 

[computer]

True,
But their method doesn't seem to allow PWM.
I was hoping for a few simple chips that can be placed on a serial bus and then have a PIC/whatever controller that does a whole load of modules.

 

[justDIY]

their method allows for pwm, they may have chosen not to enable it in software.

since this is a matrix, not a huge gob of discrete leds, there is no way to pwm a single led. you have to pwm one column at a time, and then single out a discrete pixel by strobing the row drivers. this is a software problem, not a hardware problem.

I have a pdf at home that I will post for you later, it details using time domain division to achieve variable brightness in led array pixels... I think they only talk about monochrome displays, but the same principals could be applied to a rgb display.

EDIT:

I've attached the pdf I wrote about earlier, it's by HP (Agilent), and covers a great deal about RGB matrices and even talks about some intelligent driver chips for them.