Switching device for RS-232 serial port and USB serial port
AssigneeUIS Abler Electronics Co., Ltd.
InventorsYa-Tsung Feng, Ming-Hung Chueh, Yu-Shan Liu, Yao-Jen Chang
Life of this patent
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Abstract
A switching device for RS-232 serial port and USB serial port is adapted to simultaneously provide a RS-232 serial port and a USB serial port for a micro-processor with a single USART. The switching device can automatically switch to select either of the RS-232 serial port or the USB serial port as a main interface for communicating with other external computer facilities and related peripheries. When one of the serial ports is selected as the main communication interface to communicate with one of external computers, the other one serial port thereof still can transmit signals from the micro-processor to another computer through its transmitting data pin (TXD).
Claims9
A switching device automatically selecting a main communication port from either of Recommended Protocol 232 (RS-232) or Universal Serial Bus (USB) via switching, comprising:
- a microprocessor having a Universal Synchronous Asynchronous Receiver Transmitter (USART);
- a first diode having an anode and a cathode;
- an RS-232/USART converter element connecting to the microprocessor through the first diode wherein the anode of the first diode electrically connects to the RS-232/USART converter element, and the cathode of the first diode electrically connects to the microprocessor;
- an RS-232 serial port connecting to the RS-232/USART converter element;
- a second diode having an anode and a cathode;
- a USB/USART converter element connecting to the microprocessor through the second diode, wherein the anode of the second diode electrically connects to the USB/USART converter element, and the cathode of the second diode electrically connects to the microprocessor as well as the cathode of the first diode;
- a USB serial port connecting to the USB/USART converter element;
- at least one photo-coupler device including a first terminal and a second terminal, the first terminal of the photo-coupler device being a control input, and the second terminal of the photo-coupler device including a controllable switch to disable the USB/USART converter element or RS-232/USART converter element from transmitting data to the microprocessor;
- and
- a current-limiting resistor including a first end and a second end, the first end of the current-limiting resistor connecting to the first terminal of the photo-coupler device with the second end of the current-limiting resistor selectively connecting to a control signal, whereby one of the RS-232 serial port and the USB serial port has a high priority for communication with the microprocessor, and
- wherein said disabled one of said RS-232/USART converter element or USB/USART converter element can still receive data from the microprocessor even though it is disabled from transmitting data to the microprocessor.
Dependencies are inferred from the claim text.