Arduino MEGA to control 12 nos 4 Digit LED displays

I have a requirement to be able to control 12 nos of 7-Segment LED displays using a MEGA board.

I am looking for something like the SAA1064 - which of course can be used for only 4 display units on a single I2C bus.

Though I mentioned 12 LED displays it is not that they have to be updated extremely rapidly or something like that - they just have to update once a few seconds when a proximity signal is received from a machine. SO most of the time the Arduino will just be waiting.

Any ideas ??

MAX7219 - controls 8, does a good job, reasonably cheap & available.

Yeah I am looking at it now. Looks to be SPI bus - how many MAX7219 s can operate on a single SPI bus ?

Thanks.

Mogaraghu:
Yeah I am looking at it now. Looks to be SPI bus - how many MAX7219 s can operate on a single SPI bus ?

Quite a large number, but if you go over eight in a row, it seems you may need to pay attention to buffering the signals.

They chain, much like the WS28[01][012] devices, so only ever three control lines.

What is WS28?

Would it not be easy to run the segment headers to all the 12 nos MAX7219 and then use 12 nos Digital Outputs from the Mega to control CS line of each MAX7219 as required ?

Mogaraghu:
What is WS28?

I was using Regex notation for WS2801/ WS2802/ WS2803/ WS2810/ WS2811 LED driver/ RGB chips.

Mogaraghu:
Would it not be easy to run the segment headers to all the 12 nos MAX7219 and then use 12 nos Digital Outputs from the Mega to control CS line of each MAX7219 as required ?

No.

A MAX7219 is a chip which drives and multiplexes - by itself - an array of 8 by 8 LEDs, which can include an eight digit, "7 segment" (actually 8 because you include the decimal point) display. I believe you wanted to display 12 digits, so you would use two MAX7219s, each controlling 6 digits (or one controlling 8, and one controlling 4, but 6 by 6 would be better if they are common cathode digits), chained so that Data Out from one goes to Data In of the next, CS and Clock are common to all, so three pins to control them all.

Though I made the Topic of this thread correct, my first post bit of confused. Sorry.

What I want to control is 12 nos of 4 digit LED displays. Like as below :

1111 2222 3333 4444 5555 6666 7777 8888 9999 1010 1111 1212

So there will be 12 nos MAX7219 ICs.

OK, each MAX7219 controls 8 digits, so for 12 sets of four digits you need six MAX7219s. each controlling a pair of four digit displays.

Thanks Paul. Its going to be that way …