NodeMCU - Master and UNO - Slaves (I2C communication)

Projects Programming
4

Hi,

Thanks for the suggestion. I was trying to execute your example but getting the output on the master serial monitor as follows. Could you please tell me what went wrong?

Master - NodeMCU

#include <Wire.h>

void setup()
{
  Wire.begin(D4, D3); //SDA=D4, SCL=D3
  Serial.begin(9600);  // start serial for output
}

void loop()
{
  Wire.requestFrom(8, 1);    // request 6 bytes from slave device #8
  char c = Wire.read();
  Serial.print("Reading 6-bytes from Slave-1: ");
  Serial.println(c, HEX);
  //-----------------------
  Wire.requestFrom(9, 1);    // request  bytes from slave device #8
  char d = Wire.read();
  Serial.print("Reading 7-bytes from Slave-2: ");
  Serial.println(d, HEX);
  //------------------------
  delay(1000);
}

Slave 1

#include<Wire.h>

void setup()
{
  Serial.begin(9600);
  Wire.begin(8);  ////UNO-Slave Address
  Wire.onRequest(sendEvent);
}

void loop()
{  

}

void sendEvent()
{
  Wire.write(0x13);
}

Slave 2

#include<Wire.h>

void setup()
{
  Serial.begin(9600);
  Wire.begin(9);  ////UNO-Slave Address
  Wire.onRequest(sendEvent);
}

void loop()
{

}

void sendEvent()
{
  Wire.write(0x27);
}

Master - Serial Monitor

9:15:53.418 -> Reading 6-bytes from Slave-1: 13
19:15:53.418 -> Reading 7-bytes from Slave-2: FF
19:15:54.397 -> Reading 6-bytes from Slave-1: 13
19:15:54.443 -> Reading 7-bytes from Slave-2: FF
19:15:55.421 -> Reading 6-bytes from Slave-1: 13
19:15:55.421 -> Reading 7-bytes from Slave-2: FF
19:15:56.400 -> Reading 6-bytes from Slave-1: 13
19:15:56.447 -> Reading 7-bytes from Slave-2: FF
19:15:57.426 -> Reading 6-bytes from Slave-1: 13
19:15:57.426 -> Reading 7-bytes from Slave-2: FF
19:15:58.397 -> Reading 6-bytes from Slave-1: 13
19:15:58.444 -> Reading 7-bytes from Slave-2: FF
19:15:59.418 -> Reading 6-bytes from Slave-1: 13
19:15:59.465 -> Reading 7-bytes from Slave-2: FF
19:16:00.395 -> Reading 6-bytes from Slave-1: 13
19:16:00.441 -> Reading 7-bytes from Slave-2: FF
19:16:01.413 -> Reading 6-bytes from Slave-1: 13
19:16:01.459 -> Reading 7-bytes from Slave-2: FF
19:16:02.435 -> Reading 6-bytes from Slave-1: 13