ESP32 & Nextion Can’t write to Nextion . Is it UART or Code?

Nextion Editor
1

This is my first attempt to write to a Nextion 3.2" display, but nothing shows up from the ESP32 . I was successful in creating my screen and defining some text and variable boxes on the Nextion. I set the Baud rate to 115200 on page 0 (only 1 page). When I run the ESP32 and utilize “Serial”, it prints on the serial monitor. When I utilize Serial2.print nothing happens to the Nextion. I suspect it may be the UART. I have a separate USP powering the Nextion with common ground pins If I connect the TX on the Esp32 to the RX pin nothing shows up on the serial monitor. It’s almost like the UART is not working. Here is the code:

#define ENHANCED  // 

#include "Nextion.h"

NexPage page0 = NexPage(0, 0, "page0");

NexText textNumber = NexText(0, 2, "CurrentControl");

NexText Amps = NexText(0, 1, "Amps"); //I named text block "Amps", ID=1
NexText Amps2 = NexText(0, 14, "Amps2");
NexNumber Temp =NexNumber(0,7,"Temp");

NexHotspot VoltsSet    = NexHotspot(0, 13, "VoltsSet"); //Couple of hotspots that do nothing now
NexHotspot AmpsSet    = NexHotspot(0, 14, "AmpsSet");
NexHotspot Volts12    = NexHotspot(0, 10, "Volts12");
NexHotspot Volts5    = NexHotspot(0,11, "Volts5");
NexHotspot Volts33    = NexHotspot(0, 12, "Volts33");



NexTouch *nex_listen_list[] =
{
  &VoltsSet,
  &AmpsSet,
  &Volts12,
  &Volts5,
  &Volts33,
  
  NULL
};



//----------------- S E T U P ----------------------------

void setup(void)
{
  nexInit(115200,16,17);      // Baud 115200,RX TX pins  Libary adjusted.
   Serial2.begin(115200,16,17);   //Yes the nexInit is supposed to set the pins but just desperate
 
}


//------------------- L O O P ----------------------------------------

void loop(void)
{
          Serial2.print(("Amps=\""));
          Serial2.print(("Nextion"));
          Serial2.print(("\""));
          Serial2.write(0xff);
          Serial2.write(0xff);
          Serial2.write(0xff);

         
        
 
  nexLoop(nex_listen_list);
 delay(1000);
 
}
2

A reliable baud rate is often dependent on the clock frequency of the microprocessor so only certain ones should be used as a test try 9600 and see if it works.
Now your doing something very similar to me that is changing voltages and currents, I am sending it to two solar inverters you may find my code useful I have up/down buttons for this that increment and decrement a value on the nextion then that is sent to the inverters. You can find it here Inverter Remote Screen with a Nextion - AEVA Forums

Also look at the commands for baud rate changes on the nextion best to set this when the page first loads as a command on the nextion.

3

Thanks for your reply, I will try what you said and will check out what this link says.

4

Double check what the configuration is set to within the NexConfig.h file. Possibly have to Change - #define nexSerial Serial to #define nexSerial Serial2.

Also never used nexInit(); mine works perfectly fine with Serial2.begin();

5

Thank you very much for your reply, I will check it.

6

Debugging Serial communication is easiest with a cheap logic analyzer ($8 on Amazon for a Chinese Saleae clone). This will show you within seconds if the ESP32 is sending correctly.

7

hi,
first what I have notized is that nexion not necessary start with defined baud rate even if new “defaut” is set. that why I keep default 9600 and then chane it higher. when I connect. I scan baud rate as it can be 9600 ot previously set (nextion not re-started) then I had also problems wit Esp harware serial when same time using debugger / pc connect. so use software serial for nextion. I have enhanced nextion library youcan find hints from there or use it if seen sutable… GitHub - jyberg/Enhanced-Nextion-Library: Enhanced Nextion library for Arduino, NodeMcu, Esp8266,...