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