Arduino Primo I2C bus problem

[Gaetano Criscuolo]

Hi, I try to mount some I2C devices at Arduino Primo but I can not get any results. I tried an I2C LCD that did not return any error but did not display any text. When I scan I2C devices I always return the same list, even if no external device is connected. Do you know if there is any configuration to run to use the bus? Thank you.

I2C scanner. Scanning ...
Found address: 9 (0x9)
Found address: 11 (0xB)
Found address: 13 (0xD)
Found address: 15 (0xF)
Found address: 17 (0x11)
Found address: 19 (0x13)
Found address: 21 (0x15)
Found address: 23 (0x17)
Found address: 25 (0x19)
Found address: 27 (0x1B)
Found address: 29 (0x1D)
Found address: 31 (0x1F)
Found address: 33 (0x21)
Found address: 35 (0x23)
Found address: 37 (0x25)
Found address: 39 (0x27)
Found address: 41 (0x29)
Found address: 43 (0x2B)
Found address: 45 (0x2D)
Found address: 47 (0x2F)
Found address: 49 (0x31)
Found address: 51 (0x33)
Found address: 53 (0x35)
Found address: 55 (0x37)
Found address: 57 (0x39)
Found address: 59 (0x3B)
Found address: 61 (0x3D)
Found address: 63 (0x3F)
Found address: 65 (0x41)
Found address: 67 (0x43)
Found address: 69 (0x45)
Found address: 71 (0x47)
Skip address: 72 (0x48)
Found address: 74 (0x4A)
Found address: 76 (0x4C)
Found address: 78 (0x4E)
Found address: 80 (0x50)
Found address: 82 (0x52)
Found address: 84 (0x54)
Found address: 86 (0x56)
Found address: 88 (0x58)
Found address: 90 (0x5A)
Found address: 92 (0x5C)
Found address: 94 (0x5E)
Found address: 96 (0x60)
Found address: 98 (0x62)
Found address: 100 (0x64)
Found address: 102 (0x66)
Found address: 104 (0x68)
Found address: 106 (0x6A)
Found address: 108 (0x6C)
Found address: 110 (0x6E)
Found address: 112 (0x70)
Found address: 114 (0x72)
Found address: 116 (0x74)
Found address: 118 (0x76)
Done.
Found 55 device(s).

[MartinBL]

That's pretty strange. Can you point me to the code you are using for this?

[Gaetano Criscuolo]

Hi Martin, yes, this is code.

#include <Wire.h>

void setup() {
  Serial.begin (9600);

  // Leonardo: wait for serial port to connect
  while (!Serial)
  {
  }

  Serial.println ();
  Serial.println ("I2C scanner. Scanning ...");
  byte count = 0;

  Wire.begin();
  for (byte i = 8; i < 120; i++)
  {
    if (i != 72) // Questo indirizzo blocca Arduino Primo
    {
      Wire.beginTransmission (i);
      if (Wire.endTransmission () == 0)
      {
        Serial.print ("Found address: ");
        Serial.print (i, DEC);
        Serial.print (" (0x");
        Serial.print (i, HEX);
        Serial.println (")");
        count++;
        delay (1);  // maybe unneeded?
      } // end of good response
    }
    else
    {
      Serial.print ("Skip address: ");
      Serial.print (i, DEC);
      Serial.print (" (0x");
      Serial.print (i, HEX);
      Serial.println (")");
    }
  } // end of for loop
  Serial.println ("Done.");
  Serial.print ("Found ");
  Serial.print (count, DEC);
  Serial.println (" device(s).");
}  // end of setup

void loop() {}

[MartinBL]

Do you have a logic analyzer so you can see if the Primo transfers anything at all? It seems like beginTransmission() doesn't actually transmit anything and that endTransmission() is happy with that and returns 0 every time.

[Gaetano Criscuolo]

No, I do not have a logical analyzer. How can I do? I have two Arduino Primo and behave the same way.

[MartinBL]

Did you try to queue a byte with Write.write() after Wire.beginTransmission, as suggested in my link?