I recently have tried to connect an LCD to my Arduino Uno. The tutorial tells me I need a 220 Ohm resistor, but the only ones I have are 330 Ohm. Does it matter?

Here's the Fritzing diagram by the way:

enter image description here

  • You can use the 330 ohm resistor. If the display's backlight is not bright enough, you could add a second 330 ohm resistor in parallel with the first one. – VE7JRO Jul 19 '18 at 17:11

No, it doesn't matter. That resistor is just for the backlight LEDs. The larger the resistor the dimmer the backlight will be. As @VE7JRO suggests, you can always put two 330Ω resistors in parallel, which will halve the resistance to 165Ω, which will give a brighter backlight.

  • It works! But when I power the Arduino through USB, the pixels are hard to read when looking straight in (this is not the case for when I use my battery pack with 6 x 1.2V rechargables). Maybe it's a problem similar to that in arduino.stackexchange.com/questions/22083/…. Anyway, I an send you pictures if you want – R Harrington Jul 20 '18 at 17:14
  • Just adjust your contrast. – Majenko Jul 20 '18 at 17:15
  • With the potentiometer? I've tried - I doesn't work (plus I've also tried s 330 Ohm resistor and a 470 Ohm resistor). By the way, it isn't a huge problem. I can always use the battery pack – R Harrington Jul 20 '18 at 17:18
  • Potentiometer adjusts contrast. Check your connection. It's pins should go to (left)Battery+, (middle)V0, (right)Battery-. This creates a voltage divider and turning it's knob changes voltage on (middle)V0 pin and it informs the LCD controller how to set the contrast. And about the resistor you can even ignore it and just connect LCD directly to Battery+. – Filip Franik Jul 20 '18 at 20:20

Nope. The lcd has backlight led which needs to powered separately. More resistance, dimmer it will be. Higher voltage decreases life span of your lcd backlit.

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