Hdmi source detection

Abstract

A circuit for detection of an HDMI source device to an HDMI sink device through an HDMI sink connector without regard for the activity state of the HDMI source device has a pull-up resistor connecting a DC power source to the DDC/CEC ground node. The node is readable as a binary signal to indicate the presence of a source device to the HDMI sink connector, where the node exhibits a logic low signal when either the node is grounded by the DDC/CEC GROUND pin connection to a source device or when a switching device is switched on. This abstract is not to be considered limiting, since other embodiments may deviate from the features described in this abstract.

What is claimed is: 
     
         1 . An arrangement for detecting a connection state of a plurality of HDMI sink connectors, comprising:
 a plurality of sink connectors residing on an HDMI sink device;   a corresponding plurality of pull-up resistors connected to the DDC and CEC ground of each of the sink connectors;   a corresponding plurality of connection state detectors that detect a state of connection of each of the sink connectors by detecting the DDC and CEC ground state;   where the DDC and CEC ground state is produced either by a ground connection through the respective sink connector from an HDMI source, or by a switched ground at the DDC and CEC ground connection created within the sink device by a switch;   a storage device that stores the state of each respective connector; and   a polling circuit that polls each of the connection detectors and stores the state of connection of each of the connection detectors to the storage device.   
     
     
         2 . The arrangement according to  claim 1 , where the polling is carried out on a periodic basis. 
     
     
         3 . The arrangement according to  claim 1 , where the polling is carried out after powering up the HDMI sink device. 
     
     
         4 . The circuit according to  claim 1 , where each switching device comprises a junction transistor switch. 
     
     
         5 . The circuit according to  claim 4 , where each node is coupled to it's respective transistor's collector, each HDMI sink connector's power pin is coupled to it's respective transistor's base and each transistor's emitter is grounded. 
     
     
         6 . The circuit according to  claim 1 , where each switching device comprises at least one of a field effect transistor switch, a relay and a logic switch. 
     
     
         7 . The circuit according to  claim 2 , further comprising a storage device that stores an signal indicative of whether or not each HDMI sink connector is connected to an HDMI source device. 
     
     
         8 . The circuit according to  claim 7 , where each HDMI connector is polled on a periodic basis to determine whether it is connected to an HDMI source device. 
     
     
         9 . A method for detecting a connection state of a plurality of HDMI sink connectors, comprising:
 providing a plurality of connection state detectors that detect a state of connection of each of a plurality of sink connectors by detecting a DDC and CEC ground state at the sink connectors;   where a plurality of pull-up resistors are connected to the DDC and CEC grounds of the sink connectors at a node;   where the connection state detectors detect a connection by detecting that a connection state is at a logic ground level produced either by a ground connection through the respective sink connector from an HDMI source, or by detecting a switched ground state at the DDC and CEC ground connection created within the sink device by a corresponding switch within the sink device;   polling each of the connection detectors to determine its state of connection; and   storing the state of connection of each of the connection detectors to the memory.   
     
     
         10 . The method according to  claim 9 , where the polling is carried out on a periodic basis. 
     
     
         11 . The method according to  claim 9 , where the polling is carried out after powering up the HDMI sink device. 
     
     
         12 . The method according to  claim 9 , where each respective switch comprises transistor switch. 
     
     
         13 . The method according to  claim 12 , where each node is coupled to its respective transistor's collector, each HDMI sink connector's power pin is coupled to its respective transistor's base and each respective transistor's emitter is grounded. 
     
     
         14 . The method according to  claim 12 , where each transistor switch comprises at least one of a field effect transistor switch, a relay and a logic switch. 
     
     
         15 . The method according to  claim 14 , where each HDMI connector is polled on a periodic basis. 
     
     
         16 . A circuit for detection of an HDMI source device to an HDMI sink device through an HDMI sink connector without regard for the activity state of the HDMI source device, comprising in combination:
 an HDMI sink connector having a DDC and CEC ground;   a pull-up resistor having first and second terminals with the first terminal coupled to a DC power source;   the second terminal being further coupled to a DDC and CEC ground of the HDMI sink connector and forming a circuit node; and   the circuit node being readable as a binary signal to indicate the presence of a source device to the HDMI sink connector, where the node exhibits a logic low signal when the circuit node is grounded by the DDC and CEC ground connection to a source device.   
     
     
         17 . The circuit according to  claim 16 , further comprising a storage device that stores an signal indicative of whether or not the HDMI sink connector is connected to an HDMI source device. 
     
     
         18 . The circuit according to  claim 16 , where the HDMI connector is polled on a periodic basis to determine whether it is connected to an HDMI source device. 
     
     
         19 . The circuit according to  claim 18 , further comprising a storage device that stores an signal indicative of whether or not each HDMI sink connector is connected to an HDMI source device. 
     
     
         20 . The circuit according to  claim 16 , where each switching device comprises at least one of a junction transistor switch, a field effect transistor switch, a relay and a logic switch.