设计采用P3口作为扫描键盘接口，P1.0口作为输出，P1口低4位接4X4矩阵键盘的列，高4位接行。

CPU工作在查询方式下并开放中断，且将定时器T1设为最高优先级。当程序扫描到按键时调用延时防抖后再次扫描并判断键值，并转入相应的按键处理子程序，在子程序中向定时器装入初值并启动其工作，当定时器溢出时向CPU申请中断，CPU响应中断后转入中断子程序，输出预定频率的方波并送到音频放大模块进行放大输出。

-Design uses a scanning keyboard interface port P3, P1.0 port as output, P1 port access 4X4 low 4 matrix keyboard out, the high four connected lines. CPU operating mode and open the query interrupt, and set the timer T1 the highest priority. When the scan delay to the call button again after the scan and determine the anti-shake key, and transferred to the corresponding key processing subroutine, the subroutine is loaded to the timer and start the initial work, when the timer overflows apply to the CPU interrupt, CPU interrupt to the interrupt subroutine, after the output frequency to and intended to amplify the audio amplifier module output.