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I am new to Arduino development. I need to connect multiple led displays(between 20 and 100), such as this one to an Arduino board. The led displays will be pretty far out from each other.

How can this be achieved? How can i uniquely identify the LCD displays? At this point i need some 101 orientation.

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    The product, that you linked, is an OLED display, not an LCD display – chrisl Jun 9 '20 at 13:53
  • okay, thanks, so how many? – Mihai Raulea Jun 9 '20 at 14:05
  • Without any additional electronics: Exactly one. On each I2C interface every address needs to be unique. Since you cannot change the address of the display, 1 is the limit. Majenkos answer gives you a hint how to deal with that. – chrisl Jun 9 '20 at 14:24
  • @chrisl on the SSD1306 you can select a second address, but I'm not sure the PCB in the product listed, breaks out the D/C# pin. Even then, you can only connect two. You could bitbang I2C on other pins. But you'd need two pins for each display, and you would run out of pins pretty quick. Also the library you use for the displays might only support the hardware I2C pins. – Gerben Jun 9 '20 at 17:43
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The led displays will be pretty far out from each other.

Those are I2C connected displays. I2C is not designed (though there are technologies to allow it) to operate over long distances. It's designed primarily for communication between chips within a circuit board.

How can i uniquely identify the LCD displays?

Since you can't change the I2C address of the displays you would either need a separate I2C bus for each one or employ some form of I2C multiplexer.

All of this is getting too complicated. The more accepted way of doing this would be to have a small microcontroller directly connected to each display (one display per microcontroller) and then make the microcontrollers communicate with each other (or with a single master) over some suitable communication medium (some wireless system, or a serial bus like RS485 or CAN, for example).

You're then just rubber-stamping the units as many times as you want, and connecting them all together.

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