Sending multiple data between the two NodeMCU using Serial communication

Question

I'm working on communicating between the two NodeMCU basing on the serial communication protocol. I've used SoftwareSerial and ArduinoJson library for my program according to some sources on the Internet. The problem is at the stability of the reading value from Serial. As far as what I saw on the COM monitor, it was either lack of data or appeared some odd letter. I want the two Node to be able to send and receive data from each other but the instability has stopped me in the first direction. Anyone's help will be appreciated. I'm trying to apply UART because of its simplicity and speed but the suggestion of another solution with other protocols would be great. The code of the transmitting node and the receiving node was attached below:

The sending program

#include <ArduinoJson.h>
SoftwareSerial s(D5,D6);
byte C1;
void setup() {

  pinMode(D0,OUTPUT);
s.begin(115200);
}
 

void loop() {
 

  //Sending code
   StaticJsonBuffer<1000> jsonBuffer;
  JsonObject& root = jsonBuffer.createObject();
  root["Temp"] = 100;
  
if(s.available()>0)
{
 root.printTo(s);
}

The receiving program

#include <SoftwareSerial.h>
SoftwareSerial s(D6,D5);
#include <ArduinoJson.h>
 
void setup() {
  // Initialize Serial port
  Serial.begin(115200);
  pinMode(D0,OUTPUT);
  s.begin(115200);
  while (!Serial) continue;
 
}
 
void loop() {
 
 //Receiving code
StaticJsonBuffer<1000> jsonBuffer;
  JsonObject& root = jsonBuffer.parseObject(s);
  
  if (root == JsonObject::invalid())
    return;
 
  root.prettyPrintTo(Serial);
  Serial.print("Data 1 ");
  Serial.println("");
  int data1=root["Temp"];
  if(data1==100)
  digitalWrite(D0,HIGH);
  else
  digitalWrite(D0,LOW);
  delay(100);
}

Answer 1

You should provide a string or char array into the

  JsonObject& root = jsonBuffer.parseObject(s);

The s variable is an object here for SoftwareSerial library.

You firstly need to read the serial like

while(s.available()){

String r = s.readString();
JsonObject& root = jsonBuffer.parseObject(r);
}

Here r will be a raw json array and json object will parse it. And it will be good if you upload your output to understand and see what is really going on

Update:

Using UART with 115200 baudrate without delay and with jumper cables may cause the miss of the characters.

The other issue is, maybe this is happenning because of monitoring the Serial port at the same time. Maybe you can debug it with just looking the digital pins which you are controlling to understand your code is working fine or not.You can

Or you can try I2c communication which is synchronous and more reliable and faster instead of UART.

Actually, SoftwareSerial library is a bit slower than the actual serial port.