Serial LCD Help

I am trying to connect my arduino to a Matrix Orbital LCD (glk12232-25) through serial communication.

I can't seem to get the LCD to respond to anything I send it, can anyone help me out?

Here is pretty much what I am doing

void setup() {
  Serial.begin(19200); //This is what the LCD's default baud is set to
  Serial.print(254,BYTE);
  Serial.print(88,BYTE);
  Serial.print("Test");
}

This should clear the LCD, then print Test at the top left corner, but It isn't actually doing anything. The LCD is displaying a solid bar on the right side of the screen.

I only have 3 wires from the arduino to the LCD, GND, 5V, and the arduino's TX connected to the LCD's RX.

Any ideas?

Thanks!

At the risk of making a fool of myself, but I think you need to connect the Arduino pin marked RX to the SerialLCD RX pin. Looking at the schematic of the UNO it appears this pin is connected to the TX pin of the ATmega. This is for the Arduino UNO, don’t know if it applies to anyother variations, and I can’t confirm that this is 100% accurate information as I haven’t used the TX/RX pins successfully yet. It’s just what I see when I look at the schematic.

On the silkscreen for the UNO there’s a little arrow by the TX and RX pins. I think this arrow is supposed to indicate direction of data flow, if I’m correct. If I’m not then I’m sure there’s plenty of people out there to correct me. :smiley:

I am pretty sure it is Arduino Tx to LCD's Rx, but I tried it your way as well and it did not work :(

If it is of any help, here is the manual for the LCD http://www.bipom.com/lcds/manuals/glk12232-25-wbl.pdf

Thank you for your reply!

I think I found my problem. The LCD only accepts RS232 values while the Arduino outputs TTL :(

I will look into i2c.

I will look into i2c.

How will that help? The Arduino can not put out +12V/-12V signals, no matter which pins you use.

You need a MAX232 chip to do the TTL to RS232 level conversion.

How will that help? The Arduino can not put out +12V/-12V signals, no matter which pins you use.

He is going to use I2C instead of serial. The LCD supports both.

Don

The LCD only accepts RS232 values while the Arduino outputs TTL

Most RS-232 devices will accept inverted TTL.

If you don't have a digital inverter chip (like, say, a 74HC14) handy, you can use an NPN transistor as an inverter. Or an N-channel FET.