Receiving 255 values from Wire.Request.From Master-Slave

Using Arduino Networking, Protocols, and Devices
1

Hi,

I've deployed a master-slave system where: 1)the master triggers the slaves with a given value through wire.write 2)the slave receives this value and within a For loop performs some tasks sending a result to the master through wire.write 3) the master does a Wire.RequestFrom waiting for those bytes (15) and printing those values on a screen.

The master receives the values but those are not the ones sent by the slave (should be hexadecimal numbers: 0x01, 0x02, 0x03 and 0x04). Instead, the master receives the following values 0, 255, 255, ... , 255 (14 times 255).

I insert the codes below:

Master

const int buttonSel = 50;//button to Select options
const int buttonStart = 53; //button to Start option
const int buttonStop = 52; //button to Stop option
const int Marcia = 32; //Initiates Marcia of the TX module
const int PR17 = 22; //PR17 relay of the TX module
const int PR16 = 24; //PR16 relay of the TX module
const int PR15 = 26; //PR15 relay of the TX module
const int PR27 = 28; //PR27 relay of the TX module
const int PR26 = 30; //PR26 relay of the TX module
const int PR25 = 31; //PR25 relay of the TX module
const int PR11 = 33; //PR11 relay of the TX module
const int PR10 = 34; //PR10 relay of the TX module
const int PR9 = 35; //PR9 relay of the TX module
const int PR5 = 36; //PR5 relay of the TX module
const int PR6 = 37; //PR6 relay of the TX module
const int PR14 = 38; //PR7 relay of the TX module (It is PR7 in TX but PR14 in RX)
const int PR23 = 39; //PR23 relay of the TX module
const int PR22 = 40; //PR22 relay of the TX module
const int PR21 = 41; //PR21 relay of the TX module
int programCount = 0;//variable to move through the program
int delay_ = 500;
//int flagStart = 0;
int read;
int pass = 0; // integer to indicate if at least one pins doesn't pass 0-OK 1-FAIL
int Error = 0; // integer to indicate that there is an error during the checking 0-NO 1-YES
int x; int y; int z;
const byte SLAVE_ADDRESS = 42;
const byte MY_ADDRESS = 25;
int flag = 0;
int count = 0;

#include <Wire.h>
#include <hd44780.h>                       // main hd44780 header
#include <hd44780ioClass/hd44780_I2Cexp.h> // i2c expander i/o class header
hd44780_I2Cexp lcd; // declare lcd object: auto locate & auto config expander chip

void setup() {
  lcd.begin(20, 4);
  Serial.begin (9600);
  Wire.begin (25);
  //Wire.onReceive(receiveEvent);
  lcd.setCursor(0, 0);
  programCount = 0;//start at the beginning
  //pinmode and digitalWrite statements  
  lcd.print("Select");
  
}

void loop()
{
  switch (programCount)
  {
    case 0: // This case option remains the "Select" option idle
      if (digitalRead(buttonSel) == HIGH)
      {
        programCount = 1;
      }
      break;
    
    case 1:
      static const uint8_t arraypin[] = {PR5, PR6, PR9, PR10, PR11, PR14, PR15, PR16, PR17, PR21, PR22, PR23, PR25, PR26, PR27};
      x = 15;
      lcd.clear();
      lcd.print("E");
      delay(delay_);
      if (digitalRead(buttonSel) == HIGH)
      {
        programCount = 2;
      }
      if (digitalRead(buttonStart) == HIGH)
      {
        lcd.clear();
        lcd.print("Start ");
        digitalWrite(Marcia, LOW);
        delay(2000);
        digitalWrite(Marcia, HIGH);
        for (int i = 0; i < x; i++)
        {
          digitalWrite(arraypin[i], LOW);
          Wire.beginTransmission (SLAVE_ADDRESS);
          Wire.write (y = arraypin[i]);
          Serial.println("Transmiting from Master");
          Serial.println(y);
          Serial.println("Receiving from Slave");
          int n = Wire.requestFrom(42, 15);
          if (n == 15) {
            flag = 1;
          }
          delay(15000);
          Serial.println(n);
          Serial.println(flag);
          if (n == 15 && flag == 1)
          {
            Serial.println("yes");
            for (int i = 0; i < x; i++)
            {
              byte z = Wire.read();
              delay(100);
              Serial.println(z, DEC);
            }
            //delay(15000);
            flag = 0;
          }
          Wire.endTransmission ();
          digitalWrite(arraypin[i], HIGH);
        }
      }
      if (digitalRead(buttonStop) == HIGH)
      {
        lcd.clear();
        lcd.print("Stop Edilbox");
        digitalWrite(Marcia, LOW);
        delay(delay_);
      }
      break;
    
    case 2:
      
      break;
    
    case 3:
      
      break;
  }

}

Slave

const int STOP  = 8; //STOP of the RX module
const int CLAX = 9; //CLAX of the RX module
const int START = 10; //START of the RX module
const int LAMP = 11; //LAMP of the RX module
const int PR17_NO = 37; const int PR17_NC = 36; //PR17 relay of the TX module
const int PR16_NO = 39; const int PR16_NC = 38; //PR16 relay of the TX module
const int PR15_NO = 41; const int PR15_NC = 40; //PR15 relay of the TX module
const int PR27_NO = 25; const int PR27_NC = 24; //PR27 relay of the TX module
const int PR26_NO = 27; const int PR26_NC = 26; //PR26 relay of the TX module
const int PR25_NO = 29; const int PR25_NC = 28; //PR25 relay of the TX module
const int PR11_NO = 45; const int PR11_NC = 44; //PR11 relay of the TX module
const int PR10_NO = 47; const int PR10_NC = 46;  //PR10 relay of the TX module
const int PR9_NO = 49; const int PR9_NC = 48; //PR9 relay of the TX module
const int PR5_NO = 53; const int PR5_NC = 52; //PR5 relay of the TX module
const int PR6_NO = 51; const int PR6_NC = 50; //PR6 relay of the TX module
const int PR14_NO = 43; const int PR14_NC = 42; //PR7 relay of the TX module
const int PR23_NO = 31; const int PR23_NC = 30; //PR23 relay of the TX module
const int PR22_NO = 33; const int PR22_NC = 32; //PR22 relay of the TX module
const int PR21_NO = 35; const int PR21_NC = 34; //PR21 relay of the TX module
//static const uint8_t arraypin[] = {PR5, PR6, PR9, PR10, PR11, PR14, PR15, PR16, PR17, PR21, PR22, PR23, PR25, PR26, PR27};
int delay_ = 700;
int x; int flag = 0; int y;
const byte MY_ADDRESS = 42;
const byte MASTER_ADDRESS = 25;
//char PIN[] = "pin";
int pin = 0;
#include <Wire.h>
#include <hd44780.h>                       // main hd44780 header
#include <hd44780ioClass/hd44780_I2Cexp.h> // i2c expander i/o class header
hd44780_I2Cexp lcd; // declare lcd object: auto locate & auto config expander chip

void setup() {
  Wire.begin (MY_ADDRESS);
  lcd.begin(20, 4);
  Serial.begin (9600);
  lcd.setCursor(0, 0);
  Wire.onReceive(receiveEvent);
// pinmode statements  
}

void loop() {

  //delay(delay_);
  if (flag == 1)
  {
    if (y == 36) {
      pin = 0; check(pin);
    } //PR5 relay of the RX module
    else if (y == 37) {
      pin = 1; check(pin);      
    }
    else if (y == 35) {
      pin = 2; check(pin);      
    }
    else if (y == 34) {
      pin = 3; check(pin);      
    }
    else if (y == 33) {
      pin = 4; check(pin);      
    }
    else if (y == 38) {
      pin = 5; check(pin);      
    }
    else if (y == 26) {
      pin = 6; check(pin);      
    }
    else if (y == 24) {
      pin = 7; check(pin);     
    }
    else if (y == 22) {
      pin = 8; check(pin);      
    }
    else if (y == 41) {
      pin = 9; check(pin);      
    }
    else if (y == 40) {
      pin = 10; check(pin);      
    }
    else if (y == 39) {
      pin = 11; check(pin);      
    }
    else if (y == 31) {
      pin = 12; check(pin);      
    }
    else if (y == 30) {
      pin = 13; check(pin);      
    }
    else {
      pin = 14; check(pin);
      
    }
    
  }
}

void receiveEvent(int howMany) {
  y = Wire.read();
  flag = 1;
}

void check (int pin)
{
    Wire.beginTransmission(25);
  static const uint8_t arraypin_NO[] = {PR5_NO, PR6_NO, PR9_NO, PR10_NO, PR11_NO, PR14_NO, PR15_NO, PR16_NO, PR17_NO, PR21_NO, PR22_NO, PR23_NO, PR25_NO, PR26_NO, PR27_NO};
  static const uint8_t arraypin_NC[] = {PR5_NC, PR6_NC, PR9_NC, PR10_NC, PR11_NC, PR14_NC, PR15_NC, PR16_NC, PR17_NC, PR21_NC, PR22_NC, PR23_NC, PR25_NC, PR26_NC, PR27_NC};
  int z = 15;
  
  Serial.print("PIN"); Serial.println(pin);
  for (int i = 0; i < z; i++)
  {
    if (i == pin)
    {

      if (digitalRead(arraypin_NO[i]) == 0 && digitalRead(arraypin_NC[i]) == 1)
      {
        
        Wire.write(0x01);
        Serial.println("1");
      }
      else
      {
        
        Wire.write(0x02);
        Serial.println("2");
      }
      delay(delay_);
    }
    else
    {
      if (digitalRead(arraypin_NO[i]) == 1 && digitalRead(arraypin_NC[i]) == 0)
      {
        
        Wire.write(0x03);
        Serial.println("3");
      }
      else
      {
        
        Wire.write(0x04);
        Serial.println("4");
      }
      delay(delay_);
    }

  }
  flag=0;
  Wire.endTransmission();

  
}

What I'm missing? Thanks

2

You should NOT be trying to read the slave response before ending the master's request. The call to beginTransmission() sets up a buffer to store data in. write() puts data in that buffer. endTransmission() actually sends the data to the slave.

It is pointless to expect the slave to have a response before you've finished asking it for anything.

3

I solved that issue, however, I'm still getting the wrong values. Is the information sent by the slave saved within the Wire.requestFrom at the master? Or it is just an indication of the expected information? How can I read the data from the slave correctly?

4

I solved that issue

So, the code you posted is not the code you are running. And, the code you are running has some problems.

Well, I think you know what you need to do.

5

You want me to paste the same code again instead of answering my questions?

6

REM14:
You want me to paste the same code again instead of answering my questions?

Of course not. You said:

I solved that issue

which means, or at least strongly implies, that you changed the code.

Well, I don't want to guess what changes you made.

7

@OP

You may consult the following codes to see how data exchange takes place between Master and Slave using I2C Bus. In this example, Master requests for 15-byte data; in response, the Slave sends the data bytes: 0x01, ..., 0x0F.

Master UNO Codes

#include <Wire.h>
byte dataArray[15];

void setup()
{
  Serial.begin (9600);
  Wire.begin (25);   //Master coulde be seen as slave
  
  Wire.beginTransmission(42); //addressing slave
  Wire.write('*'); //request code to send data
  Wire.endTransmission();
  //----------------------------------
  Wire.requestFrom(42, 15);  //request for 15 bytes
  for (int i = 0; i < 15; i++)
  {
    dataArray[i] = Wire.read();
    Serial.print(dataArray[i], HEX); //print received bytes
    Serial.print(" ");
  }
  Serial.println();

}

void loop()
{

}

Slave NANO Codes

#include<Wire.h>
const byte MY_ADDRESS = 42;
const byte MASTER_ADDRESS = 25;
bool flag1 = LOW;
byte myData[15];

void setup() 
{
  Serial.begin(9600);
  Wire.begin (MY_ADDRESS);
  Wire.onReceive(receiveEvent);
  Wire.onRequest(sendEvent); 
}

void loop() 
{


}

void receiveEvent(int howMany) 
{
  byte x = Wire.read();
  if(x == '*')
  {
    flag1 = HIGH; //request has come
    for(int i=0; i<15; i++)
    {
      myData[i] = i+1; //prepare data
    }
  }
}

void sendEvent(int howMany)
{
  if(flag1 == HIGH)
  {
    for (int i = 0; i<15; i++)
    {
      Wire.write(myData[i]);
      Serial.print(myData[i], HEX); //print send data 0x01, ..., 0x0F
      Serial.print(" ");
    }
    Serial.println();
  }
}

scr-10.png

BTW: Connect 2x2.2k pull-up resistors on the I2C Bus.

scr-10.png