Problem with instruction Serial.readStringUntil(char)

[multimedia999]

Hello,
I am testing a little application using a nextion screen and a arduino uno R3.
When I want to received the strind sent by the nextion screen to the ardiuno thrue the serial (TX, RX), wheb I use Serial.readString(), it is working.
But if I try the instruction Serial.readStringUntil(char), the compiler sned a warning and doesn't take the instruction.
Somebody can help me?
Daniel

[paulpaulson]

@multimedia999

Somebody can help me?

Hello multimedia999

Post your sketch, well formated, with comments and in so called code tags "</>" and schematic to see how we can help.

Have a nice day and enjoy coding in C++.

[johnwasser]

@multimedia999

if I try the instruction Serial.readStringUntil(char), the compiler sned a warning and doesn't take the instruction.

What warning? I suspect you tried to send a string "\n" instead of a character '\n'.

[multimedia999]

Here is the code:
Actually I have another poblem , it seems that my arduino is dead !!!!!! but before he die

String fromnextion=" ";
String signe=" ";
// include the library code:
#include <LiquidCrystal.h>
// initialize the library with the numbers of the interface pins

LiquidCrystal lcd(7, 8, 9, 10, 11, 12);

void setup() {
Serial.begin(9600);
Serial.setTimeout(100);

// set up the LCD's number of columns and rows:
lcd.begin(16, 2);
/* Print a message to the LCD.
lcd.setCursor(4,0);
lcd.print(distance);
lcd.setCursor(13,0);
lcd.print("=>");
lcd.setCursor(1,0);
lcd.print("<="); */
}

void loop() {
// set the cursor to column 0, line 0
// (note: line 1 is the second row, since counting begins with 0):
lcd.setCursor(0, 0);

fromnextion=Serial.readString(); /* if I replace this line by
fromnextion=Serial.readStringUntil("#"); I have a
warning */

signe=fromnextion.substring(0,1);
lcd.print("");
lcd.setCursor(0,1);
lcd.print(fromnextion);

[johnwasser]

@multimedia999

fromnextion=Serial.readString(); /* if I replace this line by
fromnextion=Serial.readStringUntil("#"); I have a
warning */

As I said. You are trying to pass a string literal ("#") instead of a character literal ('#').

[GolamMostafa]

@multimedia999

fromnextion=Serial.readStringUntil("#"); I have a

Do you understand/know the difference between "#" (# is within pair of double quotes) an '#' (# is within pair of single quotes)?

[multimedia999]

Ok , I will try as soon I will have the possibility , and I come back to give the result.
Thanks a lot for your time.
Daniel

[PerryBebbington]

Hello @multimedia999,
As you are posting in the English section of the forum please could you edit your title to be in English?

I thank you.

[multimedia999]

Ok, it is ok for the compiler, but the result is not what I expected. I expected the string before the limiter.
But I will work in another way.
My arduino is not dead. That's only that it cannot upload the sketch if the RTX is in use with another component (like a nextion screen)

[StefanL38]

@multimedia999

I expected the string before the limiter.

What do you mean by writing this?
please describe in detail:
what is the complete string that the nextion display is sending?
what do you receive?

Me personal I prefer sending userdefined strings over the nextion-standard strings in combination with non-blocking receiving
This means quite some modifications to the code but the advantage is that the microcontroller is responsive to nextion input all the time
user-defined strings were sent with the nextion-function prints
best regards Stefan

[multimedia999]

That is my own string defined in the even of a button, I send it to the arduino by the serial interface

[StefanL38]

You could modify your string to have a start-character and an end-character and then use non-blocking receiving like explained in the serial input basics tutorial example 3 receive with start / end-character
example

start-character "<"
end-character ">"

Start and end-character can be included or excluded in the variable that is used for receiving

Serial Input Basics - updated

Updated Version Please note that this is a revised version of the advice in this earlier Thread which has become very long. As far as possible I have kept the code examples identical or simplifed them slightly. It should not be necessary to refer to the older Thread, but feel free to do so. Contents The following sections are in this Tutorial Introduction Serial data is slow by Arduino standards Example 1 - Receiving single characters Why code is organized into functions Exampl…

best regards Stefan

[PerryBebbington]

Here is my way of working with Nextion displays:

Using Nextion displays with Arduino

Introduction Nextion displays include either a resistive touch panel (RTP) or capacitive touch panel (CTP) and provide an easy way to create a touch screen interface, or human machine interface (HMI) for your project. The displays require a spare serial port to communicate with them. To get the best from them requires an understanding of how to drive them, and what works and doesn't work. The advice here is based on my work with multiple projects using Nextion displays with both PIC and Arduino…