Hellooooo,

I'd like to use 4 big digits to display a number. I am a bit confused about the number of drivers I'll need. The idea is we have 1 arduino, sending a 4 digit number to the displays through a driver.
As I quote from the wiki of using the big digit display driver

"The BDD is designed to be used to drive a large number of digits from a single controller (Arduino or otherwise). As mentioned above, the BDD can carry up to five amps, allowing up to seven displays in series from a single power supply. To propagate data and clock signals down a series of displays BDD boards can be 'daisy chained' by connecting the 'output' SPI header of a display to the 'input' SPI header of the next display in the series."

So : do I need 1 or 4 controllers??

An answer will be mucho appreciado

It sounds like the source of confusion is between the terms "driver" and "controller."

The Big Digit Driver (BDD) is a big, brainless "backpack" board that fits onto a single 12" LED digit, and manages the current through all the little tiny LEDs that make up each of the segments that make up the great big digit. You need a separate BDD for each digit that you want to drive. So, to drive four digits, you'll want to get 4 BDD kits.

The controller-- the Arduino in your case --is the "brain" of the system, and sends a signal out to a string of one or more BDDs. One Arduino can send data to a string of 4 BDDs, so you only need one controller.