LM8942芯片的底层双路电机驱动电路板的嵌入式程序，通过串口通信接受上位机发送的控制指令，输出PWM波形对电机调速，然后通过QEI模块读取双路编码器信息上传给上位机-LM8942 the underlying chip dual motor drive circuit board embedded programs, accept control commands sent by the host computer, the output PWM waveform of the motor s