ESP32 to Nextion HMI Lessons Learned

@rebeljd WHOA, modifying a library is a big nono. And the lines you modified are normal so why?

@zander 

based on advise by another user to make the ESP32 port2 work on the Nextion.  It works fine.  I did not try it without modifying the library but I might.

@rebeljd You are basically removing the Serial.begin(baud) from one place and sticking it in another. I doubt that does anything useful. What it does do, is prevent you from getting updates to your library since doing so would break it again if it is indeed broken. Have you checked if there is an outstanding issue for this?

It is EXTREMELY rare to find a library bug, I think I have only encounter two.

If it is a problem, I think you can use github to manage it (I know almost nothing about github). Just a guess, but maybe a fork?

I had a look at the documentation the author created and I think maybe either you are setting up the display wrong or the author made a mistake. See attached pic

This release is 2 years old so I find it difficult to believe he has not fixed the bug in that length of time.

The second pic is of the open Issues. I see nothing about a Serial issue.

@zander 

Ron, I also had to comment out a line in the EasyNextionLibrary for my project I documented last fall.  This is from my project post:

I used the Easy_Nextion_Library for the displays because it was the easiest for me (based on my limited experience).  I did make one change in the EasyNextionLibrary.cpp file - I commented out the _serial->begin(baud) line (line 24 – see below) and initialized the object in my code.  I was having trouble assigning the Nextion display to Serial2 when I also had to assign the serial pins.  Getting the Nextion display to work with the ESP32S3 was the biggest issue I had in this project. 

The ESP32 needs you to assign your serial pins, something the EasyNextionLibrary does not allow (you may not remember, but you were advising me when I was having this issue).  I commented out the Serial.begin in the library and added it to my code.

For reference, here is the link to my posts.  

Forgot the link: https://forum.dronebotworkshop.com/show-tell/rabbit-shack-chicken-coop-automation-project/

@zander 

One more thing...I did sent an email to the library owner asking to change the library to allowed to assigning serial port pins in the library, but never heard back.

@huckohio What is needed is to use github and enter an issue. Given what I see on github this library has not been touched for over a year so either the maintainer has died or is otherwise no longer maintaining the library. If it was me I would use a different library.

I just realized another reason. Library maintainers are bombarded by incorrect reports of errors, and it is simply too time consuming to respond.

Can I see just the one line of code you used in your setup to perform the Serial initialization?

@huckohio @rebeljd Show me your 1 line of startup code that initializes the Serial port.

Library authors are inundated with false error reports and do not have time to respond to them. I just tried one of the samples and it is setup for Serial as I expected and compiles clean even at ALL. I can see the error in rebeljd's code and even after I pointed it out I am hearing nothing.

@zander 

Ron, here is the line from the library that I commented out: 

 //_serial->begin(baud);  // We pass the initialization data to the objects (baud rate) default: 9600

And here is the line I used in my Setup:

  // Init Serial2
  Serial2.begin(9600, SERIAL_8N1, RXp2, TXp2);

This is from the declaration section of the code :

EasyNex myNex(Serial2);

@huckohio Ok, if you look at the example sketches they do NOT use Serial.begin, they use MyNex.begin(9600); 

Both you and @rebeljd are using Serial.begin which I believe is incorrect. I base that on the fact that the examples are coded as MyNex.begin(9600), NOT Serial.begin. I am certainly no expert in C++ but I am pretty sure the example sketches are coded correctly. I looked at 6 examples in the Easy_Nextion library and they are all coded this way.

I may very well be wrong, but I am basing my comments not on an expert knowledge of C++ which I do not have, but on pattern recognition, and my experience with open source authors. 

I had a look at the library code, and the following is the constructor

EasyNex::EasyNex(HardwareSerial& serial){ // Constructor's parameter is the Serial we want to use
_serial = &serial;
}

If you did NOT call myNex.begin(9600), then commenting out that code does nothing.

If you do call myNex.begin(9600) then the removed code does exactly what your Serial2.begin does but it does a lot more. Look at the library code if you doubt me.

I urge you to try a test, put the removed library code back, then change your statement of Serial2.begin( to myNex.begin(9600)

Here is the begin code you may be not using if I am understanding you. I am including the constructor as well.

EasyNex::EasyNex(HardwareSerial& serial){ // Constructor's parameter is the Serial we want to use
_serial = &serial;
}

void EasyNex::begin(unsigned long baud){
_serial->begin(baud); // We pass the initialization data to the objects (baud rate) default: 9600

delay(100); // Wait for the Serial to initialize

_tmr1 = millis();
while(_serial->available() > 0){ // Read the Serial until it is empty. This is used to clear Serial buffer
if((millis() - _tmr1) > 400UL){ // Reading... Waiting... But not forever......
break;
}
_serial->read(); // Read and delete bytes
}
}

@Zander

Posted by: @zander

↑

but I am pretty sure the example sketches are coded correctly.

I am sure the examples ARE coded correctly (for the vision of the developer at the time), unless you need to assign the RX & TX pins to a serial port on the ESP32.  The library will not allow you to use the this statement 

Serial2.begin(9600, SERIAL_8N1, RXp2, TXp2);

to assign Serial2 to the GPIO pins. I tried.  

You were trying to help me with this problem last year until you told me that this topic bored you and you stopped.  This was the only way that I found that worked.  My approach was verified some months later when I saw the exact approach in the Nextion forum (but I don't have the link).

I believe the library example uses:  EasyNex myNex(serial);

...and then in setup uses: myNex.begin(9600) 

But I needed Serial2 which required assigning GPIO pins (example above) which the library does not support.

Either way,  what I did works and has been working on three ESP32S3s with NEXTION devices for more than 9 months.

I fail to see the issue with moving the initialization of a serial port (which is typically in setup) from the library back to the program ino file.  Like I said...it worked for me and it seems to have worked for @rebeljd

@huckohio Agreed, but I am a purist and when I was younger would have persued the author to fix his code. All that is required is to add parameters for the additional config with default values. I will raise an issue with the maintainer.

@huckohio I don't see the extra args in the docs, for my personal education could you point me at the appropriate doc? I only see baud and 8N1 amongst others, but nothing after that.

Did you consider using Serial for the Nextion then the library could be used as is, and using Serial2 for your other needs?

Now that I more fully understand what is going on I wish I had a display, but they are very confusing. Many are over $100 some even over $500 and the less expensive models under $50 all say they work with old Pi's, no mention of ESP32. Do you have any recommendations?

I am seriously considering modifying the library code and then releasing it as a new better library if I can find a reasonably priced display.