Scope of application of this manual: iTOP-4412 Elite Edition Android4.0.3 system
In the "RFID_Module_v1.1.zip" hardware data compression package, it provides the schematic diagram and
PCB in Cadence format, the schematic diagram in AD format and PC, and the schematic diagram in PDF format .
The linux driver of the RFID module is the "drivers/spi/rc522.c" file in the kernel directory, which is already included in the default kernel image.
The Android test routine provides the "iTOP-4412-Android-RFID_V1.x" compressed package, and the test APK is the "rfidtest.apk" file in the "bin" directory under the compressed package.
2 Hardware connection
If the development board is connected to the "sdiowifi module" and the wifi is turned on, the wifi can be used normally, but the RFID cannot be used.
This document test uses a development board, an RFID module. Connect the development board and the RFID module with a ribbon cable. The port of the relay module is connected to the "GPIO" port on the development board
as shown in the figure below. 
After the hardware connection is completed, the software test can be performed.
3 Software test
After the development board runs the Android system, connect the development board to the computer with OTG.
Install "360 Mobile Assistant" on your computer . Double-click "rfidtest.apk" in the "bin" directory of the source code, and select "Start
Sending .
Put the RFID tag whose information you want to read on the module, as shown in the figure below. 
Click the "RECV" button on the development board screen to read the card information on the module. The reading is successful as shown in the figure below. 
The card reading fails, as shown in the figure below. 
If the card reading fails, you can observe whether the small light on the card reader module is lit, if not, check whether the hardware is connected properly. In addition, it must be noted that on the android4.0.3 system, wifi and rfid cannot be used at the same time, so when testing, be sure not to open the wifi module.
In addition, click the "CLEAR" button to clear the text box information.