multiple dot matrix

Hi I'm newbie and I'm trying to control multiple matrix.
What I have is "keyes 595 display pcb" using 74HC595 shift register
which looks like this


http://en.keyes-robot.com/productshow.aspx?id=415

I successfully connect one dot matrix
but I want to connect multiple of 595 display

When I use max7219 there was cs pin, It was easy with LedControl.h
but, in 595 display there is no cs pin but latch pin
pins are gnd, 5v, clk, latch, data

is it possible to control multiple 595 display?
or do I need another driver or register?

thanks

Sure, you can daisy chain 595s. Latch is the MAX7219 cs signal.

Coding would be a lot simpler by adding additional MAX7219 tho, it takes cares of the multiplexing, you just send data to 1 of 8 registers.
MAX7219 can be daisychained, or you can parallel CLK and LATCH and DATA and have a unique CS to each one, then you're just selecting one bank of 8 shift registers (all that MAX7219 is from code perspective) to send data out to with the unique CS pins.

I am still not clear how he would program these modules.

CS and LATCH are pretty much the same thing, but the ICs you are controlling are quite different.

As Crossroads says, the 7219 IC will do all the multiplexing for you, you just tell it what needs to be displayed.

I don't have experience with your 595 based display, but usually these work by setting up the pattern for one row (or column,depending on how it is wired) in the other IC and then turning on (or off, again, depending wiring) to complete a circuit to turn the row on. Repeat this very quickly for all the rows and columns. Basically you have to manually in code do what the 7219 will do for you automatically.

ebdev:
What I have is "keyes 595 display pcb" using 74HC595 shift register which looks like this
Free-shipping-font-b-keyes-b-font-8X8-font-b-dot-b-font-font-b-matrix.jpg
http://en.keyes-robot.com/productshow.aspx?id=415

That's terribly sad, because that is a really, really badly designed module - you have pretty much bought a "dud".

These are the ones you should be using.

They are so cheap you are better off to just scrap the ones you have and buy the proper ones.

I can't find a schematic for the red PCB he bought. How would he go about programming it?

If he buys the other ones, I hope the seller sends him the right 8x8 LED matrix. There is a recent thread about the wrong type of 8x8 LED matrix being sent. It seems as if I have some sitting at my post office box waiting for me. :frowning:

ieee488:
I can't find a schematic for the red PCB he bought. How would he go about programming it?

Just trace out the PCB connections to the 74HC595s. Really you only need to know which are clock, data and latch and they should be marked on the PCB anyway. You then write code to - as I explained somewhere else - shift an array of bytes into the registers and then play with that code writing patterns (0b00000001, 0b00010000, two bytes at a time for the first module) to the registers to correlate these with what is displayed.

The problem is that 74HC595s are not really capable of driving such a matrix array and the design "cheats" by not using current limiting resistors, so that if one row or column is selected, the brightness will vary substantially according to how many LEDs in that row/ column are driven at the moment.

And to display anything more than a single row or column on each, you have to write continuous multiplexing code.

The MAX7219s OTOH, perform all the multiplexing for you and contains the proper current drivers to deliver (more than) adequate brightness.

ieee488:
If he buys the other ones, I hope the seller sends him the right 8x8 LED matrix. There is a recent thread about the wrong type of 8x8 LED matrix being sent. It seems as if I have some sitting at my post office box waiting for me. :frowning:

Well, of course the seller I cited is demonstrated to be competent. Your problems noted and replied (some time ago to begin with)!

Paul__B:
Well, of course the seller I cited is demonstrated to be competent. Your problems noted and replied (some time ago to begin with)!

Demonstrated to be "competent" how?
You only know after you receive the items.

Your seller has 99.8% feedback rating.

The one who sent the wrong ones in the other thread has 99.7% I have bought from him too in the past, and he was reliable.

ieee488:
Demonstrated to be "competent" how?
You only know after you receive the items.

Yes, I daresay I have bought stuff from "Alice".

ieee488:
The one who sent the wrong ones in the other thread has 99.7% I have bought from him too in the past, and he was reliable.

Perhaps. But considering the severe limitations of the feedback system (only 60 days to report problems and takes 25 days to receive something and thus another 25 days to receive a replacement if that was promised following a complaint to the vendor), that 0.1% may mean a lot! :grinning:

You have to actually look at the feedback and see to what the red icons refer.

Paul__B:
Yes, I daresay I have bought stuff from "Alice".
Perhaps. But considering the severe limitations of the feedback system (only 60 days to report problems and takes 25 days to receive something and thus another 25 days to receive a replacement if that was promised following a complaint to the vendor), that 0.1% may mean a lot! :grinning:

You have to actually look at the feedback and see to what the red icons refer.

I have bought stuff from "alice" and I have bought some from "gc_market" and various other sellers for that matter.

I don't put more stock in one seller than the other.

I have 6 months with Paypal to file a claim. That is all I care about.