Automatic VGA monitor detection

摘要

Various embodiments of the present invention relate to methods, systems and devices of employing a monitor detection module in a computer to automatically detect the presence of a VGA display. Such a system for automatic VGA monitor detection comprises a central processing unit (CPU), a GPU, a VGA connector and the monitor detection module. The CPU provides image information to the GPU which further processed the image information to generate video signals according to a VGA display standard. The video signal comprises analog video signals (i.e., red, green and blue) and synchronization signals (i.e., horizontal and vertical). The video signals are transmitted to the VGA connector at the interface of the computer. A VGA monitor or projector may be connected to the computer at the VGA connector via a VGA data cable. The monitor detection module receives at least one of the analog video signals and at least one of the sync signals, identifies a monitor detection pulse synchronous with the sync signal, and monitors the impedance at the pin for the analog video signal at the VGA connector during the monitor detection pulse. The monitor detection module takes advantage of synchronization pulses in the horizontal or vertical sync signal to monitor termination resistance of an analog video signal line, and thus, the VGA display may be detected reliably at a fast rate without interfering with video signal transmission.

主权项

1. A monitor detection module for automatic monitor detection in a computer, comprising:
a monitoring control circuit coupled to a GPU in the computer, the monitoring control circuit receiving a sync signal from the GPU and generating an enable signal that comprises a monitor detection pulse based on synchronization pulses in the sync signal; a bias element coupled to a pin that is associated with an analog video signal in a VGA connector, the bias element driving the pin for the analog video signal; a plurality of switches coupled to the monitoring control circuit, the plurality of switches being controlled by the enable signal to couple the bias element to a power supply and decouple the GPU from the pin for the analog video signal during the monitor detection pulse; and a signal processing module coupled to the pin for the analog video signal, the signal processing module generating at least one control signal according to a voltage at the pin for the analog video signal.