初始状态为待命，数码管熄屏。 按按钮到下一个状态，数码管显示倒计时 倒计时之后等待一段时间led灯亮起，按下按钮后显示反应时间，然后等待一段时间后返回等待状态。(1. Idle, which is the default state, is not responding to the test being executed. 2. This will inform users that a new reaction test is about to start. For example,