LCD0821 Serial Connection W/Arduino UNO

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GarettFox
LCD?
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LCD0821 Serial Connection W/Arduino UNO

Post by GarettFox » Mon Oct 06, 2014 12:14 pm

I'm trying to get my LCD0821 to display text sent to it via Serial connection from an Arduino UNO R3, with an Ethernet shield. However, there seems to be a problem with the ASCII encoding, or the baud, or both, because the screen displays gibberish similar to a few other peoples' on this forum, and none of the solutions they've found have helped. I tried changing the baud from the specified 19200; I even wrote a sketch that cycles through every baud from 10 to 30000 in multiples of 10 and tries to clear the screen and display the current baud on the screen. There were a few points at which the screen was successfully cleared, but it proceeded to still display gibberish. I also tried rewriting the ASCII encoding and having the Arduino send the decimal codes for each character individually instead of automatically through Serial.write() or Serial.print() (I tried both of those, too), and I've also tried the Manual Override, but I still get a bunch of symbols and other nonsense.

Clark
Matrix Orbital
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Re: LCD0821 Serial Connection W/Arduino UNO

Post by Clark » Mon Oct 06, 2014 1:16 pm

Hi Garett,

If you haven't already, please make sure your LCD0821 is set to TTL mode to match your Arduino serial voltage levels. As you've mentioned, you can also place the display in manual override mode, and setup your serial port at 19200 baud with the default SERIAL_8N1 configuration to try to send a single known letter.

For examples of how to build commands, you might adapt the I2C application note for the Arduino. If you continue to have trouble in serial mode, please provide your compelte clear screen code and I can replicate with our Uno R3 here.

Cheers,
Troy
Troy Clark
Design & Development
Matrix Orbital

GarettFox
LCD?
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Joined: Mon Oct 06, 2014 12:01 pm

Re: LCD0821 Serial Connection W/Arduino UNO

Post by GarettFox » Mon Oct 06, 2014 1:22 pm

How do I set it to TTL mode? The manual says to put jumpers on the TTL pins, but there are no TTL pins to put jumpers on.

Clark
Matrix Orbital
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Re: LCD0821 Serial Connection W/Arduino UNO

Post by Clark » Mon Oct 06, 2014 1:26 pm

Hi Garett,

There is a protocol select resistor block on the back of your LCD0821, near the middle of PCB. By default it is populated with 3 resistors on the RS232 jumpers, you'll need to carefully remove those 3 jumpers and connect the 2 TTL jumpers with either 0 ohm resistors or solder.

Cheers,
Troy
Troy Clark
Design & Development
Matrix Orbital

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