I2C - master sometime not receive data

Projects Programming
1

HI all.
Master random not receive data, receive function sometime not start/run. When i clera old data and receive new, the rec function not start.

Master:

m_test = true;

Wire.beginTransmission(1);
Wire.write(&ETH_to_i2c[0],12);
Wire.endTransmission();


ETH_data_out[12] = 0; //delete old data
ETH_data_out[13] = 0; //delete old data
ETH_data_out[14] = 0; //delete old data

i_pocitadlo_i2c = 12;
Wire.requestFrom(1, 12);
while (Wire.available()) 
{
byte c = Wire.read();
ETH_data_out[i_pocitadlo_i2c] = c;
 i_pocitadlo_i2c++;
m_test = false; //when function run, all is good, no error
      }
if (m_test){Serial.println("no comm");} //sometime is error, function no run, i dont now why

Slave:

void setup()
{  
  Wire.onReceive(I2C_receive);
  Wire.onRequest(I2C_transfer);
}

void I2C_transfer()
{
  OUT_I2C_data[0] = 5;

  OUT_I2C_data[1] = DATA_rueck;


  //tested crc function
  m_calc_crc_out = true;
  crc_generate2_out.CRC_gen(m_calc_crc_out, OUT_I2C_data[0], OUT_I2C_data[1]);
  m_calc_crc_out = false;

  OUT_I2C_data[2] = crc_generate2_out.CRC;


  //tested crc function
  m_calc_crc_out = true;
  crc_generate_out8.CRC_gen_8(m_calc_crc_out, &OUT_I2C_data[3]);
  m_calc_crc_out = false;

  OUT_I2C_data[11] = crc_generate_out8.CRC;


  Wire.write(OUT_I2C_data, 12);
}

Max cycle time of master is 10ms, slave 5ms.
Receive I2C function on masted every 30ms.

Why sometime atmel print in console "no comm" ?

2

Post complete code, both sketches don't compile!