Patent ID: 8452905

Claim:
A serial port remote control circuit, comprising: a first interface circuit to receive recommended standard 232 (RS232) level signals and convert the RS232 level signals to transistor-transistor logic (TTL) level signals, or receive TTL level signals and convert the TTL level signals to RS232 level signals; a control circuit connected to the first interface circuit, to convert the TTL level signals to physical bus signals, or convert physical bus signals to TTL level signals; an output circuit connected to the control circuit, to convert the physical bus signals from the control circuit to network bus signals, or convert network bus signals to physical bus signals and output the physical bus signals to the control circuit; a power circuit connected to the first interface circuit, the control circuit, and the output circuit, to provide a first voltage and a second voltage to the control circuit, the first interface circuit, and the output circuit; and a second interface circuit connected to the control circuit and the power circuit, to download control programs to the control circuit; wherein the control circuit comprises a microcontroller, a crystal oscillator, a switch, a first connector, first and second resistors, and first to third capacitors, wherein first to third voltage pins of the microcontroller are connected to the power circuit, a first clock pin of the microcontroller is connected to one terminal of the first capacitor, and the other terminal of the first capacitor is grounded, a second clock pin of the microcontroller is connected to one terminal of the second capacitor, and the other terminal of the second capacitor is grounded, the crystal oscillator is connected between the first and the second clock pins of the microcontroller, a reset pin of the microcontroller is grounded through the switch, connected to the power circuit through the second resistor, and also grounded through the third capacitor, first and second input/output (I/O) pins of the microcontroller are connected to the output circuit, a setting pin of the microcontroller is connected to first and third pins of the first connector through the first resistor, a fourth pin of the first connector is connected to the power circuit, third to seventh I/O pins of the microcontroller are connected to the second interface circuit, eighth and ninth I/O pins of the microcontroller are connected to the first interface circuit.