I'm very new to Arduino and came to a point where I'm interested in playing with shields, such as LCDs.

For example, I really like the looks of "LCD 1602 with keypad" module, but it seems to be using a lot of pins.

  • By looking at a module / shield, how can I tell (or at least estimate) which pins will be used and which ones I will have left if I stack them with my Uno or Mega without printed schematics?
  • look at datasheet
    – Martynas
    Commented Dec 15, 2014 at 14:02
  • My question is asking about figuring out (or estimating) by looking at a module.
    – Phil
    Commented Dec 15, 2014 at 18:47

2 Answers 2


If you look in the 'Tutorials' section of this page you can see the pins used. All of the buttons come through in one analogue input and you'll need a further 7 digital I/O pins. So 8 in total which would leave 5 analogue and 4 digital (I think) pins on an Uno.

As for how to tell which ones, does it matter in advance? I would just map the I/O in the sketch to suit. If you need to plan that far in advance though, it seems that J5 in this schematic shows which pins travel through the shield (i.e. are available to use in conjunction with the shield). Also J6 shows the 5 remaining analogue pins.


why dont you use an i2c adapter for this type of display? search for i2c display module. i2c only needs 2 wires for data and clock and 2 for power. you can also easily locate the SDA and SCL pins on your arduino

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