键盘的实现（完成4X4）
.....................\boot.mcp
.....................\boot.S
.....................\boot_Data
.....................\.........\CWSettingsWindows.stg
.....................\.........\Debug
.....................\.........\.....\TargetDataWindows.tdt
.....................\.........\DebugRel
.....................\.........\........\boot.axf
.....................\.........\........\boot.bin
.....................\.........\........\ObjectCode
.....................\.........\........\..........\boot.o
.....................\.........\........\..........\FIQ_Handler.o
.....................\.........\........\..........\IRQ_Handler.o
.....................\.........\........\..........\main.o
.....................\.........\........\TargetDataWindows.tdt
.....................\.........\Release
.....................\.........\.......\TargetDataWindows.tdt
.....................\IRQ_Handler.S
.....................\main.c