输出1Khz互补的PWM波形，占空比每隔1s变化5 ，变化范围10 -90 ，从10 不断增加到90 ，然后减小到10 ，如此循环。-Output 1Khz complementary PWM waveform, duty cycle changes every 1s 5 , 10 -90 range, continuously 10 to 90 , and then decreased to 10 , so the cycle.