SMbus 的準位與標準的 I2C 不一樣，SMBus 是 3.3V 所以 Schmitt Trigger 的準位與使用5V的I2C觸發準位不一樣。如果 PIC16F4620 使用在 3.3V 也是 O.K.

如果使使用 putsI2C( ):
Return Value:
Master I2C mode:

0 if the null character was reached in the data string

-2 if the slave I2C device responded with a NOT ACK

-3 if a write collision occurred

Slave I2C mode:

0 if the null character was reached in the data string

-2 if the master I2C device responded with a NOT ACK which terminated the data transfer

若是使用 EEBytewrite( ) 的話其結果又不一樣，所以要看 PIC18 Peripheral Libraries 才知道詳情: C:\mcc18\doc\periph-lib\I2C.htm

EEBytewrite( ) ; Return Value:
0 if there were no errors

-1 if there was a bus collision error

-2 if there was a NOT ACK error

-3 if there was a write collision error

MCC18裡面的I2C函式用法:

OpenI2C(MASTER, SLEW_OFF);// Initialize I2C module
StartI2C();
SSPADD = 9; //400kHz Baud clock(9) @16MHz

EEByteWrite(Device_ID,Device_Address,Data);
EERandomRead(Device_ID,Device_Address)

return (-3) :應該是表示return某種錯誤訊息
要看執行到哪一個判斷才知

想請問一下如果想要用PIC18F4620話,
可以直接用MCC18裡面的I2C含函式用在SMbus Interface嗎??

我看PIC18F452裡面的DATA sheet,
SSPSTAT Register中的

CKE: SMBus Select bit
In Master or Slave mode:
1 = Enable SMBus specific inputs
0 = Disable SMBus specific inputs

可是PIC18F4620裡面的並沒有,
是不是這樣就沒辦法直接使用阿?
麻煩大大們替我解答一下了...
弄好久,好像匯流排都會衝突就跳出來了..
我有接2顆10K的提升電阻至VCC,

另外想在問一下 return (-3)
這樣打有什麼作用阿??
看不太懂他函式庫的寫法