MAX7219 & multi-digit 7-segment displays

If you have the following 7-segment displays:

2-digit 3-digit 4-digit

is it possible to control the 2-digit, 3-digit and the first 3 digits of the 4-digit 7-segment display from a single MAx7219, and then control the remaining digit of the 4-digit display from another MAx7219? Or do you have to ensure you control all digits from the same MAX7219?

If I can do that, then I can use 10 MAX7219's for my project instead of 14.

Or do you have to ensure you control all digits from the same MAX7219?

Yes you do. That is the only way the anodes can be driven synchronised to the cathodes.

There is a way to get your 9th digit onto the same max7219. If you don't need the decimal points, you can use a 4-digit, a 3-digit and a 1-digit common cathode displays, but don't connect the DP pins, plus a 1-digit common anode display connected to the unused DP pin.

Of course, this is messy in terms of components and wires, and even messier in terms of the code!

I’ll revert to my original plan and control the digits via MAX7219s, eg 2-digit + 3-digit, then the 4-digit on its own, then 5 pairs of 2 x 3-digits. Will be much easier to design the PCB for anyway.

Sounds a little wasteful. Surely we can do better, Andy? How many of each size of display do you need to drive? What's the layout for the displays?

Could you wire 4 X 2-digit displays to one Max chip, and 4 more max chips for the pairs of 3-digit and 4-digit displays? That gets you 4 groups of displays with 5 max chips.

Another alternative to consider is ht16k33 chips. Each can drive up to 16 digits. So the first chip could drive 2+3+4+2+3, the second chip would drive 4+2+3+4+2, the third chip 3+4+2+3+4 and so on. That's 5 groups of displays with 3 chips. Only problem might be that it is tricky to use more than 8 of these chips together.