LCD_I2C display blocks Arduino's serial monitor

Official Hardware Nano Family Classic Nano
1

Hi together,
while develop my project I'm polling sensors and display and control the results on serial monitor. Works!
Now I installed a I2c LCD 20x4 and it works also separately.
But: Now the serial monitor is blocked when the LCD is installed!!
I tested some Liquid cristal LIBs - without succesess..
What's my mistake?

2

Can you tilt the screen a bit, there is a glare and I can't quite read your code or see your wiring.

3

With no sketch, and no schematic, all I can suggest is to look at line 42.

Seriously though, show your sketch. Show a schematic. Show your wiring.

5

ok-sorry. The scatch in detail is not important..... So I show you the scheme:

**Start:**
#include <LiquidCrystal.h>
#include <Wire.h> 

**Setup:**
lcd.begin();                               
lcd.backlight();                            
lcd.setCursor(0, 0);  
lcd.print("abs 123...");     //here some lcd.print  in line 0 to 3  for start info   working!

Serial.begin(9600);     

**LOOP**          
Serial.print("123.33   ");   // here some data, polled in a function         working!
                                                output at Arduino's serial monitor
lcd.setCursor(0, 0);  
lcd.print(" data");             // entering this line no serial data is shown in the monitor
                                                system hangs....

it`s a conflict between internal Serial. print and I2C pins A4 / A5. Serial pins TX/RX (0 and 1) are not connected . The wirering is checked and ok.

6

Since you won't provide the requested information necessary to resolve your issue, I'm done here.

7

Ahh, but it is. See, what you posted as a concept is not problematic, so the problem must reside in the code you did not post.
Like others, I've departed.

8

Actually, which LCD library is that? There are very many; often, I2C-capable ones, though, have I2C in the name...

9

Only one possible cause remains. Human error.

10

Thankx for your response.
The problem is NOT in the loop gathering the data to be displayed. This works!

The problem is:
When the first data line (Serial println("...") is send to the serial monitor it is displayed correctly.

Then next- the data is send to the LCD - nothing appears on the display BUT
the system hangs.

If I skip the serial part the data is shown in the LCD correctly and the systems runs!
???
???

11

This is not consistent with your talk about I2C pins.
The non-I2C version of the Liquid Crystal library requires multiple pin definitions and which do not appear in your code.

12

Locked as this is a duplicate, please see:

@pgroener ,

Please post your questions once. Duplicate posting can lead to a suspension from the forum.

Thank you.