Grove - Serial LCD

Products & Technology Grove
#1

Hello,

I’m using a 16x2 Grove - Serial LCD v1.1 display attached to an Arduino Uno board. Running the example script the display shows “Hello world!” but the contrast is that dark that it’s only visible if you look to it from the side.

I found a remark on the wiki page: http://www.seeedstudio.com/wiki/Grove_-_Serial_LCD claimimg the following features: “A variable resistor(R4) for LCD contrast ratio adjustment”. Where is that R4 on the board? How can I adjust the contrast of the display? I tried a 10k POT on pin 3 of the display itself connected to +5V and GRD of the Arduino but it doesn’t really work. The display just switched off when the voltage came to high close to 5V. Connecting pin 3 of the display to GRD has no visible effect at all…

Any idea?

Many thanks.
Ralf

#2

Got it solved.

But I can’t understand why :slight_smile:

I disconnect the USB link which I used as power supply. Intead I connected a 5V power source to the power supply connector. All other connections remain the same and now the LCD display has shown a good contrast.

Any idea what the reason could be?

Thansk & best regads
Ralf