ESP8266 Community Forum

- Fri Oct 23, 2015 3:23 am #32100 Hi.
I use I2C to connect ESP8266 with Arduino.

Master Code on ESP8266:

Code: Select all#include <Wire.h>
//#include <Time.h>  //only on arduino
struct DATA_STRUCTURE {
  time_t czas_kontrolny;
  float temp_ds, temp_dht, temp_bmp, humi_dht, srednia;
  int32_t pressure;
} volatile data;

union u_tag {
  byte b[4];
  float fval;
  time_t time_tval;
  int32_t int32_tval;
} u;

char bufor[100];

void setup() {
  Serial.begin(9600);
  //  Wire.begin(); //only on arduino
  Wire.begin(0, 2); //only on ESP8266
  Wire.setClock(100000);//only on ESP8266
}

void loop() {
  delay(500);
  int available = Wire.requestFrom(3, sizeof(data));

  if (available == sizeof(data))
  {
    Serial.print("odczyt danych: ");

    for (int i = 0; i < 4; i++) u.b[i] = Wire.read();
    data.czas_kontrolny = u.time_tval;
    for (int i = 0; i < 4; i++) u.b[i] = Wire.read();
    data.temp_ds = u.fval;
    for (int i = 0; i < 4; i++) u.b[i] = Wire.read();
    data.temp_dht = u.fval;
    for (int i = 0; i < 4; i++) u.b[i] = Wire.read();
    data.temp_bmp = u.fval;
    for (int i = 0; i < 4; i++) u.b[i] = Wire.read();
    data.humi_dht = u.fval;
    for (int i = 0; i < 4; i++) u.b[i] = Wire.read();
    data.pressure = u.int32_tval;
    data.srednia = (data.temp_bmp + data.temp_ds + data.temp_dht) / 3;

    Serial.print("[");
    Serial.print(data.czas_kontrolny);
    Serial.print("|");
    Serial.print(data.temp_ds);
    Serial.print("|");
    Serial.print(data.temp_dht);
    Serial.print("|");
    Serial.print(data.temp_bmp);
    Serial.print("|");
    Serial.print(data.humi_dht);
    Serial.print("|");
    Serial.print(data.pressure);
    Serial.println("]");
  }
  else
  {
    Serial.print(F("Blad odczytu - nieprawidlowa ilosc danych: "));
    Serial.println(available);
  }
}

Slave code on Arduino UNO

Code: Select all#include <Wire.h>
#include <Time.h>

struct DATA_STRUCTURE {
  time_t czas_kontrolny;
  float temp_ds, temp_dht, temp_bmp, humi_dht;
  int32_t pressure;
}  data;

char bufor[100];

void setup() {
  Wire.begin(3);                // join i2c bus with address #8
  Wire.onRequest(requestEvent);  //mega requesting data

  Serial.begin(9600);           // start serial for output
  Serial.println("START");
}

void loop() {

}

void requestEvent()
{
  byte  *ArrayOf24Bytes;
  data.czas_kontrolny = now();

  data.temp_bmp = 24, 70; //for test
  data.pressure = 100049;//for test

  Serial.print("do wyslania: ");
  Serial.print("[");
  Serial.print(data.czas_kontrolny);
  Serial.print("|");
  Serial.print(data.temp_ds);
  Serial.print("|");
  Serial.print(data.temp_dht);
  Serial.print("|");
  Serial.print(data.temp_bmp);
  Serial.print("|");
  Serial.print(data.humi_dht);
  Serial.print("|");
  Serial.print(data.pressure);
  Serial.println("]");

  ArrayOf24Bytes = (byte*) & data;

  Wire.write(ArrayOf24Bytes, 24);
}

When I use another arduino UNO as master (with additional liblary and change wire.begin function)
Every thing work correct.
But when ESP8266 is as master. Master don't receive correct data.
I check connection witch code from https://www.arduino.cc/en/Tutorial/MasterReader.
and with:
for master on esp8266

Code: Select allvoid loop() {
  Serial.print("SET to:");
  Serial.println(bb);
  Wire.beginTransmission(3);
  Wire.write(bb); //
  Wire.endTransmission();
  delay(100);
 
  Serial.println();
  Serial.print("request: ");
   Wire.requestFrom(3, bb);    // request MX 32 bytes from slave device #2
  for(int i=0;i<bb;i++)
  {
    char c = Wire.read();    // receive a byte as character
    Serial.print(c);   
  }
  delay(500);
  bb=bb+1;
  if (bb>32) bb=10;
 
}

And for slave on arduino:

Code: Select allvoid requestEvent()
{
  String inputString = "";
 // sprintf (bufor, "x:= %d",x);
 
 // Serial.println(bufor);
 // Wire.write( (byte *) bufor, 10);
 Serial.print("wyslanie :");
 Serial.println(bb);
  for (int i=0;i<bb;i++)
  {
   
    inputString+='*';
  }
  sprintf (bufor, "%s",inputString.c_str() );
  Serial.print(inputString);
  Wire.write( (byte *) bufor, bb);
  Serial.println();
}

When I try send integer value is the same problem.

This is part of bigger plan

Thanks
Pawel.