光强检测与控制--当U18 的DA0 端为5V 时，发光二极管不发光。当U18 的DA0 端为0V 时，发光二极管发光，其光强通过电阻RX2进行调节，所发出的光经过光敏电阻接收，光敏电阻值与光强成反比。当光强增大时，光敏电阻阻值减小；当光强减弱时，光敏电阻阻值增大。光敏电阻上产生变化的电压，该电压通过U2A LM358 放大输出至CH1 。-Detection and control- when U18 DA0 is 5V, the light-emitting diode does not emit light. When U18 DA0 end of 0V, light-emitting diode, the intensity is adjusted through a resistor RX2, the light emitted by the photosensitive resistance receiving, photosensitive resistance value is inversely proportional to light intensity. When the light intensity increases, the photosensitive resistance is reduced　when the light intensity is weakened, photosensitive resistance increases. The voltage change on the photosensitive resistor, the voltage amplifier output to CH1 by U2A LM358.