Data-flow along the panels

Post Reply
Finchnixer
Posts: 2
Joined: Thu Jun 26, 2008 2:21 am

Data-flow along the panels

Post by Finchnixer » Thu Jun 26, 2008 2:32 am

Hi!

I've just bought the 8x8 panel, but haven't started putting it together yet. I am however trying to understand the dataflow with multiple panels. I get the shifting of data from the Arduino into the LED-driver, but the multiple-panel setup is still a bit hazy. Am I correct in assuming that the dataflow is FIFO'ed through the chip, so you shift the last panel's data first, and finish up with the panel which has the BBB piggybacked to it? Or how do you "trigger" the data-out flow from the first panel in to the next, and so on?

I think I will have to make myself a graphical representation of the program, what registers get filled with what data etc, as it kinda is the core for understanding how to use the panel, and the Arduino for that matter.

paul
Site Admin
Posts: 735
Joined: Mon May 12, 2008 4:19 pm

Re: Data-flow along the panels

Post by paul » Thu Jun 26, 2008 5:36 am

Finchnixer,

You've got it exactly right - the data flows fifo fashion through all the chips. It's really just one big serial chain. The data for the last panel is sent first, and the panel that the microcontroller is connected to is last.

The only complexity is that with multiple panels you need to figure which data in (DI) lines and data out (DO) lines to hook up. You only need to hookup the data out of the panel containing the microcontroller to the data in line of the next panel (and not vice versa). This is simple since the pins line up across from each other.

There's nothing you have to do to trigger the data flow.

Take the latch line low
Clock out the data
Take the latch line high - all the data will be transfered to the outputs (LED's)

Hope that helps,

Paul

Finchnixer
Posts: 2
Joined: Thu Jun 26, 2008 2:21 am

Re: Data-flow along the panels

Post by Finchnixer » Thu Jun 26, 2008 10:33 am

Yupp, that's the easy part. :) Now I just have to re-re-re-read the code to understand how the scrolling works, and the order of shifting the bits into the chips, which bit is most significant etc etc.
I think a lot will be clearer when I have the circuit up and running, and can do some serial printing of the bits moving.

Post Reply