未接I2c Wire.endTransmission返回值仍正确是怎么回事？

ghostinholiday

如题，我號下了所有连线，裸板上去下载，endTransmission返回值仍为0（成功的意思）
SDA和SCL都没接是如何传输成功的？
此为我代码：
// MPU-6050 Short Example Sketch
// By Arduino User JohnChi
// August 17, 2014
// Public Domain
#include "Wire.h"
const int MPU_addr=0x68;  // I2C address of the MPU-6050
byte AcX,AcY,AcZ,Tmp,GyX,GyY,GyZ;

void setup(){
Wire.begin(6,5);
  Wire.beginTransmission(MPU_addr);
  Wire.send(0x6B);  // PWR_MGMT_1 register
  Wire.send(0);     // set to zero (wakes up the MPU-6050)
  Wire.endTransmission();
  Serial2.begin(9600);
}
void loop(){
  Wire.beginTransmission(MPU_addr);
  Wire.send(0x3B);  // starting with register 0x3B (ACCEL_XOUT_H)
SerialUSB.print("fuckendTransmission1 = "); SerialUSB.print(Wire.endTransmission());

  Wire.beginTransmission(MPU_addr);
  Wire.requestFrom(MPU_addr,14);  // request a total of 14 registers
  AcX=Wire.receive()<<8|Wire.receive();  // 0x3B (ACCEL_XOUT_H) & 0x3C (ACCEL_XOUT_L)     
  AcY=Wire.receive()<<8|Wire.receive();  // 0x3D (ACCEL_YOUT_H) & 0x3E (ACCEL_YOUT_L)
  AcZ=Wire.receive()<<8|Wire.receive();  // 0x3F (ACCEL_ZOUT_H) & 0x40 (ACCEL_ZOUT_L)
  Tmp=Wire.receive()<<8|Wire.receive();  // 0x41 (TEMP_OUT_H) & 0x42 (TEMP_OUT_L)
  GyX=Wire.receive()<<8|Wire.receive();  // 0x43 (GYRO_XOUT_H) & 0x44 (GYRO_XOUT_L)
  GyY=Wire.receive()<<8|Wire.receive();  // 0x45 (GYRO_YOUT_H) & 0x46 (GYRO_YOUT_L)
  GyZ=Wire.receive()<<8|Wire.receive();  // 0x47 (GYRO_ZOUT_H) & 0x48 (GYRO_ZOUT_L)

  SerialUSB.print("fuckendTransmission2 = "); SerialUSB.print(Wire.endTransmission());
SerialUSB.print("AcX = "); SerialUSB.print(AcX);
  SerialUSB.print(" | AcY = "); SerialUSB.print(AcY);
  SerialUSB.print(" | AcZ = "); SerialUSB.print(AcZ);
  SerialUSB.print(" | Tmp = "); SerialUSB.print(Tmp/340.00+36.53);  //equation for temperature in degrees C from datasheet
  SerialUSB.print(" | GyX = "); SerialUSB.print(GyX);
  SerialUSB.print(" | GyY = "); SerialUSB.print(GyY);
  SerialUSB.print(" | GyZ = "); SerialUSB.println(GyZ);
delay(200);
}

Super169

印象中 wire 庫的 i2c 通訊好像只是檢查你發出的資料及線路是否有問題, 但不會檢查接收方是否存在的.
在沒連線下, 線路不會有問題, 就只是對應的 i2c device 不存在.
一般會在程式開始時先向該地址發出 WHO_AM_I 的指令, 以確定接收方是否存在.