Communication system for a control channel, and corresponding method and computer program product

1. A communication system for a Consumer Electronics Control (CEC) channel of a High-Definition Multimedia Interface (HDMI) communication interface being switchable between an active condition and a standby condition, said system comprising:

a communication module for receiving messages from said CEC channel, said communication module including a timer,

a processing unit for processing said received messages, and

an oscillator separate from said timer for driving said communication module and providing a clock signal to said timer,

wherein said system is configured for:

when said interface is in said active condition:

activating said timer when the beginning of a transmission of a first message is detected on said CEC channel,

detecting the transmission start bit of said first message via said timer using a first plurality of reference values,

reconstructing and processing said first message, and

detecting the presence of other remaining activities to be performed and, in the absence of other remaining activities, switching said interface from said active condition to said standby condition by means of a deactivation of said oscillator, and

when said interface is in said standby condition:

switching said interface from said standby condition to said active condition when the beginning of a transmission of a second message is detected on said CEC channel by activating said timer and said oscillator,

detecting the transmission start bit of said second message via said timer using a second plurality of reference values, wherein said second reference values are different from said first reference values,

reconstructing and processing said second message,

wherein the reference values comprise timer count values.

2. The communication system of claim 1 , wherein the beginning of a transmission on said CEC channel is detected if said channel CEC changes from the logic level ‘1’ to the logic level ‘0’.

3. The communication system of claim 1 , comprising a multiplexer for selecting either said first plurality of reference values or said second plurality of reference values as reference values for said timer.

4. The communication system of claim 3 , comprising a control module for driving said multiplexer, wherein said control module ensures that the reference values of said timer remain stable till said transmission start bit of said second message has been detected.

5. The communication system of claim 1 , wherein the beginning of a transmission is detected asynchronously.

6. The communication system of claim 1 , wherein said first plurality of reference values includes a first reference value for the low period of the bit and a first reference value for the total bit time.

7. The communication system of claim 1 , wherein said second plurality of reference values includes a second reference value for the low period of the bit and a second reference value for the total bit time.

8. The communication system of claim 1 , wherein said communication module generates at the end of the reception of a message an interrupt, which is transmitted to said processing unit.

9. The communication system of claim 2 , comprising a multiplexer for selecting either said first plurality of reference values or said second plurality of reference values as reference values for said timer.

10. The communication system of claim 9 , comprising a control module for driving said multiplexer, wherein said control module ensures that the reference values of said timer remain stable until said transmission start bit of said second message has been detected.

11. The communication system of claim 8 , wherein the beginning of a transmission is detected asynchronously.

12. The communication system of claim 8 , wherein said first plurality of reference values includes a first reference value for the low period of the bit and a first reference value for the total bit time.

13. The communication system of claim 8 , wherein said second plurality of reference values includes a second reference value for the low period of the bit and a second reference value for the total bit time.

14. The communication system of claim 8 , wherein said communication module generates at the end of the reception of a message an interrupt, which is transmitted to said processing unit.

15. A communication method for the CEC channel of a HDMI communication interface being switchable between an active condition and a standby condition, said interface comprising a communication module for receiving messages from said CEC channel, wherein said communication module includes a timer, a processing unit for processing said received messages, and an oscillator separate from said timer for driving said communication module and providing a clock signal to said timer, said method comprising:

a) when said interface is in said active condition:

activating said timer when the beginning of a transmission of a first message is detected on said CEC channel,

detecting the transmission start bit of said first message via said timer using a first plurality of reference values,

reconstructing and processing said first message, and

detecting the presence of other remaining activities to be performed and, in the absence of other remaining activities, switching said interface from said active condition to said standby condition by means of a deactivation of said oscillator, and

b) when said interface is in said standby condition:

switching said interface from said standby condition to said active condition when the beginning of a transmission of a second message is detected on said CEC channel by activating said timer and said oscillator,

detecting the transmission start bit of said second message via said timer using a second plurality of reference values, wherein said second reference values are different from said first reference values, and

reconstructing and processing said second message,

wherein the reference values comprise timer count values.

16. A computer program product loadable into a non-transitory memory of a computer and including software code portions adapted for performing the method of claim 15 when the product is run on a computer.

17. A communication method for the CEC channel of a HDMI communication interface, said method comprising:

providing a communication module for receiving messages from said CEC channel, said communication module including a timer;

providing a processing unit for processing said received messages;

providing an oscillator separate from said timer for driving said communication module and providing a clock signal to said timer; and

switching said interface between an active condition and a standby condition,

wherein the timer receives a first and a second plurality of reference values each comprising timer count values and wherein said second reference values are different from said first reference values; and

when said interface is in said active condition:

activating said timer when the beginning of a transmission of a first message is detected on said CEC channel;

detecting the transmission start bit of said first message via said timer using the first plurality of reference values;

reconstructing and processing said first message; and

detecting the presence of other remaining activities to be performed and, in the absence of other remaining activities, switching said interface from said active condition to said standby condition by means of a deactivation of said oscillator; and

when said interface is in said standby condition:

switching said interface from said standby condition to said active condition when the beginning of a transmission of a second message is detected on said CEC channel by activating said timer and said oscillator;

detecting the transmission start bit of said second message via said timer using the second plurality of reference values; and

reconstructing and processing said second message.

18. The method of claim 17 , wherein the beginning of a transmission is detected asynchronously.