LCD display without a resistor


i have very basics question i'm new to arduino , and wanted to start by uploading hello world to my NANO and LCD i have used the example that is given to write HelloWorld , but with the corona crisis i can't get my hands on everything , i have LCD 16x2 , NANO and wires i have neither resistors or pots , i tried the example and wire it and uploaded it but the LCD just turned on with no writing , just light .

is the resistor necessary ? and why the LCD wont show any writing ? thank you

Just connect pin #3 to GND. You don't need a pot to get a readable display.

If you have a 470R resistor, put this between pin#3 and GND instead of the 0R (straight wire) Any resistor between 0R and 560R will "work".


I’m not sure to what degree Covid19 has or has not slowed down shipping from China, but I have not received my trickle of little packages for a few weeks now, which is unusual (for me!).

Nevertheless, get on eBay right now and order a nice big resistor pack - focus on values between 100 Ohm and 47k. :grinning: In fact, “hot” values would be 470 Ohms (you do not need 220 Ohms to drive LEDs to maximum), 1k, 2k2, 4k7, 10k and 47k. However, if you had just a few values between 100 and 470 Ohms you could soon find a perfect value for the contrast adjustment.

Connecting the potentiometer to Vcc - 5 V - was in actual fact a stupid design blunder made by early users of the HD44780 due to mis-reading the original “test” examples in the datasheet and even copied into subsequent datasheets of the “knock-off” clones of that chip. It does nothing else but illustrate the ability of even engineers to just be lazy and do things with no serious thought. :roll_eyes: