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Topic: Serial LCD v2.5 with Arduino Uno (Read 1 time) previous topic - next topic


I am using the Arduino Uno with SerLCD (3pins), i connect the LCD Vdd to the Uno 5V, GND to GND, and LCD RX to the Uno TX which is at pin digital (PWM (1)). I am using the SoftwareSerial Example, i change the baud rate to 9600. Everytime i upload the code it gave me a bunch of characters as soon as i unplug it and plug i it back i see the right output. Can anyone help please!!!

Code: [Select]
  Software serial multple serial test

Receives from the hardware serial, sends to software serial.
Receives from software serial, sends to hardware serial.

The circuit:
* RX is digital pin 2 (connect to TX of other device)
* TX is digital pin 3 (connect to RX of other device)

created back in the mists of time
modified 9 Apr 2012
by Tom Igoe
based on Mikal Hart's example

This example code is in the public domain.

#include <SoftwareSerial.h>

SoftwareSerial mySerial(2, 3); // RX, TX

void setup() 
// Open serial communications and wait for port to open:
   while (!Serial) {
    ; // wait for serial port to connect. Needed for Leonardo only

  Serial.println("Goodnight moon!");

  // set the data rate for the SoftwareSerial port
  mySerial.println("Hello, world?");

void loop() // run over and over
  if (mySerial.available())
  if (Serial.available())


The TX/RX pins are the same as used by the serial port (USB) to upload a new program. You litterly see your program passing by :)

It is probably better to have the serial LCD disconnected while uploading although I never had trouble with it myself.
Rob Tillaart

Nederlandse sectie - http://arduino.cc/forum/index.php/board,77.0.html -
(Please do not PM for private consultancy)


If you use the hardware serial on pins 0 and 1, you will have to disconnect the lcd during program loading, and user hardware serial, not soft.

If you use software serial on other pins, you are free to leave the lcd panel on during programming.
Serial LCD keypad panel,phi_prompt user interface library,SDI-12 USB Adapter


The problem still continue, i moved pin 1 to 3 it didn't work at all. When i change pin 2,3 to 4,5 or to 0,1 it still work the same way; whenever i upload the code its a bunch of characters as so as i unplug the USB and plug it back i get to right output.


and if you don't unplug usb but press reset ?
Rob Tillaart

Nederlandse sectie - http://arduino.cc/forum/index.php/board,77.0.html -
(Please do not PM for private consultancy)


Or unplug or disconnect the display before uploading. You can plug it in and then hit the reset button after uploading your sh=ketch.

--> WA7EMS <--
"The solution of every problem is another problem." -Johann Wolfgang von Goethe
I do answer technical questions PM'd to me with whatever is in my clipboard

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