P1.4引脚控制三极管再由三极管控制继电器 输出1三极管导通继电器得电吸合，输出0三极管截止继电器失电断开-The P1.4 pin control triode again by the triode control relay output 1 triode relay is attracted, the output of the 0 transistor cut-off relay power loss off