I feel so sorry about my poor english and presentation.
And, i thank you for your attention and teaching.
This is my situation, now.
I have changed Pin 10 to 9 successfully.
I am trying to integrate Ethernet module and RFID module.RFID-RC522
MOSI -> 11
GND -> GND
RST -> 5V
VCC -> 3.3V
Ethernet code(arduino.cc example): http://goo.gl/vL3PTq
RFID code: http://goo.gl/FWzwJw
Here is my test case:
Case 1 : RFID code(pins 9 ) + Ethernet and RFID module -> Success
Case 2 : ethernet code + Ethernet module only -> Success
Case 3 : ethernet code + Ethernet and RFID module -> Fail
(Stop in "Ethernet.begin(mac)" )
Case 4 : ethernet code + Ethernet and RFID module(remove RFID pin 12) -> Success
Case 5: RFID code (pins 9 ) + Ethernet and RFID module(remove RFID pin 12) -> Fail
In case 3 & 4, Pin 12 is blocked by RFID, but pin 12 is shared by all SPI bus devices as you say.
In this time, i want to complete Ethernet function only with rfid module.What is the function of Pin 12 (MISO)?Can i change pin 12 to other pin?
Or i miss some code which share pin 12 to muti-devices?
what does it mean? Does it mean : digitalWrite(ss, LOW); SPI.transfer(0); SPI.transfer(value); digitalWrite(ss, HIGH);
At least you have to define pin 9 as an output and drive it high (to disable it's bus usage).