Problem with sending and/or recieving data from Mega2560 to esp8266

[marcomur]

Hello,
Im using Wemos NodeMCU V3 32mb wifi module with a level converter and arduino mega.
I connected the converter as in this tutorial, under label "Using the BD-LLC for Serial" (I dont really understand this part: " Although you won't be taking advantage of the BD-LCC's bi-directional abilities, it's perfectly fine to use the board to shift serial communication"):

https://learn.sparkfun.com/tutorials/bi-directional-logic-level-converter-hookup-guide

I used exact same level converter and tried to send data from arduino using many different ways. The code for sender(arduino) looks like this:

#include <SoftwareSerial.h>
SoftwareSerial espSerial(19, 18);
String str;
void setup(){
Serial.begin(9600);
Serial1.begin(9600);
espSerial.begin(9600);
delay(2000);
}
void loop()
{
Serial.print("H: ");
Serial.print("% ");
Serial.print(" T: ");
Serial.println("C");
Serial1.print("H: ");
Serial1.print("% ");
Serial1.print(" T: ");
Serial1.println("C");
espSerial.write("H: ");
espSerial.write("% ");
espSerial.write(" T: ");
espSerial.write("C");
espSerial.print("H: ");
espSerial.print("% ");
espSerial.print(" T: ");
espSerial.print("C");
delay(1000);
}

and code for reciever(Wemos wifi) looks like that:

#include <SoftwareSerial.h>

SoftwareSerial espSerial = SoftwareSerial(5, 4);

void setup() {
pinMode(5, INPUT);
pinMode(4, OUTPUT);
espSerial.begin(9600);
Serial.begin(9600);
}

void loop() {

if(Serial.available()){
  Serial.print(espSerial.read());
}
delay(10);
}

I programmed what i wanted the arduino to do in a different program and now i just want to test sending and recieving data. The problems are:

1. after some edits/rewireing serial on Wemos shows nothing, i suppose because Serial.available() is not true
2. Serial from Wemos shows only blank squares .

Of course i connected RX to TX and so on, so thats should not be the problem.

The final project is supposed to collect data from sensors(on arduino), and send them to a web server. A part with collecting data is ready and working well, and same for the one sending data to server. I just cant transfer the sensor data from mega to wemos.

any advice would be awesome, as im not experienced, in fact im completly new to recieve/send projects.

Thanks in advance

[kgray9]

Hi @marcomur,

Welcome! Do you have your ESP RX and TX pins attached to the Mega's D19 and D18 pins?

[marcomur]

Hi, yes i had the pins connected and i think i solved the problem, after 2 days of trying.

So i edited the code for arduino to look like this:

#include <SoftwareSerial.h>

void setup(){

Serial1.begin(9600);

}

void loop()

{

Serial1.write(1);

Serial1.write(2);

Serial1.write(3);

Serial1.write(4);

}

And in my many attempts to make it work i made ports 19 and 18 as software serial, but they were already hardware serial ports, and it made the program to bug.

But now i have another problem my wemos serial looks like that

-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-11234-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-1-11234-1-1-1

do you know how to get rid of these -1s? is there a function that only gets serial when its not empty?

[kgray9]

Did you alter your ESP code also? If so could you please post it? You can remove the SoftwareSerial library from your above code. Also try adding a delay in the loop after the serial writes.

[GolamMostafa]

Have you changed your esp sketch as follows:

#include <SoftwareSerial.h>

SoftwareSerial espSerial(5, 4);//SRX = 5, STX = 4;

void setup() 
{
    //pinMode(5, INPUT);
    //pinMode(4, OUTPUT);
    espSerial.begin(9600);
    Serial.begin(9600);
}

void loop() 
{
     if(espSerial.available())
     {
          Serial.print(espSerial.read());
     }
     delay(10);
}

[marcomur]

I will be able to check the code and send it on monday, because all my work is now stuck at my workplace. I will reply and check your edits, and post wemos code then.
Thanks in advance