Method And Apparatus For Distributing Power And Data On A Single Conductor Output Line

Abstract

Light Emitting Diodes (LEDs) are increasingly used in illumination applications. To control multiple Light Emitting Diodes (LEDs), or any other controllable light source, this document introduces a single-wire multiple-LED power and control system. Specifically, individually controlled LED units are arranged in a series configuration that is driven by a control unit located at the head of the series. Each of the individually controlled LED units may comprise more than one LED that is also individually controllable. The head-end control unit provides both electrical power and control signals down a single wire to drive all of the LED units in the series in a manner that allows each LED unit to be controlled individually or in assigned groups.

1 . A electronic circuit for providing power and data on a single conductor output line, said electronic circuit comprising:
 a current source for driving a nominally constant direct current on said single conductor output line;   a data interface circuit, said data interface circuit for receiving control data;   a data frame buffer for storing at least one data frame, said data frame containing a subset of said control data received on said data interface circuit; and   a modulator circuit, said modulator circuit modulating said data frame onto said nominally constant direct current by creating detectable current deviations from said nominally constant direct current.   
     
     
         2 . The electronic circuit for providing power and data on a single conductor output line as set forth in  claim 1  wherein said detectable current deviations comprise upward and downward ramps of current from said nominally constant direct current. 
     
     
         3 . The electronic circuit for providing power and data on a single conductor output line as set forth in  claim 1  wherein said modulator circuit comprises:
 an inductor, said inductor coupled in series with said single conductor output line; 
 a transistor, said transistor coupled in series with said single conductor output line; and 
 a current modulation circuit, said current modulation circuit controlling said transistor to induce said current deviations from said nominally constant direct current. 
 
     
     
         4 . The electronic circuit for providing power and data on a single conductor output line as set forth in  claim 1 , said electronic circuit further comprising:
 a command parser and handler circuit, said command parser and handler circuit for extracting said subset of control data from said control data and placing said subset of control data into said data frame buffer.   
     
     
         5 . The electronic circuit for providing power and data on a single conductor output line as set forth in  claim 4 , said electronic circuit further comprising:
 control and status registers, said control and status registers for controlling operation of said electronic circuit;   
       wherein said command parser and handler circuit handles modulator configuration requests in said control data by modifying said control and status registers. 
     
     
         6 . The electronic circuit for providing power and data on a single conductor output line as set forth in  claim 5  wherein said command parser and handler circuit handles status requests by reading control and status registers and sending a response through said data interface circuit. 
     
     
         7 . The electronic circuit for providing power and data on a single conductor output line as set forth in  claim 1  wherein said modulator circuit modulates an empty frame onto said single conductor output line when a new data frame is not available. 
     
     
         8 . The electronic circuit for providing power and data on a single conductor output line as set forth in  claim 1  wherein said modulator circuit comprises:
 a clocking circuit, said clocking circuit generating a clock signal that controls a data modulation rate of said modulator circuit. 
 
     
     
         9 . The electronic circuit for providing power and data on a single conductor output line as set forth in  claim 1  wherein said data frame comprises a synchronization header, an address, a command, and parameter data. 
     
     
         10 . The electronic circuit for providing power and data on a single conductor output line as set forth in  claim 1  wherein said data interface circuit comprises a serial peripheral interface circuit. 
     
     
         11 . A method of providing power and data on a single conductor output line, said method comprising:
 driving a nominally constant direct current on said single conductor output line;   receiving control data with a data interface circuit;   storing at least one data frame in a data frame buffer, said data frame containing a subset of said control data received on said data interface circuit; and   modulating said data frame in said data frame buffer onto said nominally constant current by creating detectable current deviations from said nominally constant direct current with a modulator circuit.   
     
     
         12 . The method of providing power and data on a single conductor output line as set forth in  claim 11  wherein said detectable current deviations comprise upward and downward ramps of current from said nominally constant current. 
     
     
         13 . The method of providing power and data on a single conductor output line as set forth in  claim 11  wherein modulating further comprises:
 inducing current deviations from said nominally constant direct current on said single conductor output line using an inductor and transistor coupled in series with said single conductor output line. 
 
     
     
         14 . The method of providing power and data on a single conductor output line as set forth in  claim 11 , said method further comprising:
 parsing said control data with a command parser and handler circuit to extract said subset of control data from said control data; and   placing said subset of control data into said data frame buffer.   
     
     
         15 . The method of providing power and data on a single conductor output line as set forth in  claim 14 , said method further comprising:
 responding to a modulator configuration requests in said control data by modifying a set of control and status registers.   
     
     
         16 . The method of providing power and data on a single conductor output line as set forth in  claim 15 , said method further comprising:
 responding to a status requests in said control data by reading from said set of control and status registers and outputting a response through said data interface circuit.   
     
     
         17 . The method of providing power and data on a single conductor output line as set forth in  claim 11 , said method further comprising:
 modulating an empty frame onto said single conductor output line when a new data frame is not available.   
     
     
         18 . The method of providing power and data on a single conductor output line as set forth in  claim 11 , said method further comprising:
 generating a clock signal that controls a data modulation rate of said modulator circuit.   
     
     
         19 . The method of providing power and data on a single conductor output line as set forth in  claim 11  wherein said data frame comprises a synchronization header, an address, a command, and parameter data. 
     
     
         20 . The method of providing power and data on a single conductor output line as set forth in  claim 11  wherein said data interface circuit comprises a serial peripheral interface circuit.