Why do I need to connect a potentiometer to a +5V source in 1602 tutorial?

Question

I'm getting starter with the Arduino and I'm going through the classic tutorial, it says to connect the VO to a pot's wiper, and pot itself to +5v and ground, so I did.

I tuned it and it worked, but then I thought, why do I need a pot if I don't plan to move it from this value? Why don't I just replace it with a resistor? But I'm still very new to electronics, Ohm's law, etc, and I got confused.

Why do I need to connect a potentiometer to +5v source, if the resistor between VO and the GND will do? I unplugged the +5v from the pot and it still worked. I had to adjust the position, but it works just fine without it, so my question is, if it works without, why all tutorials tell us to connect it to a +5v?

Answer 1

VO controls the contrast of the LCD, which is quite temperature-dependent.

You can get away with a fixed resistor between VO and GND because of the built-in resistor between VCC and VO, producing a voltage divider.

In many cases you can also use a direct connection between VO and GND, resulting in a voltage of zero at VO.

However, be aware that the contrast changes if the ambient temperature leaves your "comfy zone". Depending on where you want to use the LCD, you need to check that out "in the field."

Answer 2

why do I need to connect, a potentiometer to +5v source, if the resistor between VO and the GND will do?

That's because the 1602 board itself (usually) has a resistor between VO and VCC. So to make voltage divider you only need to add one extra resistor from VO to Gnd (ca. 1-2K probably).

So, yes, you can go with only one resistor (or with the pot disconnected from VCC) if the board already has another resistor pre-soldered.