Radio frequency interference reduction in multimedia interfaces
View Patent ↗A device for communications over a multimedia communication interface. The device can be a source device including a scrambling circuit that receives control data associated with multimedia data to be transmitted over the multimedia channel of the multimedia communication interface, and generates scrambled control codes based on the control data. An encoding circuit generates transition minimized control codes based on the scrambled control codes. The device transmits the transition minimized control codes to a sink device via the multimedia channel. The sink device may also decode and de-scramble the transition minimized control codes received from the source device via the multimedia channel.
1. A device for communications over a multimedia communication interface having a plurality of multimedia channels, comprising:
a random number generator to generate random numbers;
a scrambler circuit to receive control data associated with multimedia data to be transmitted over a multimedia channel of the plurality of multimedia channels of the multimedia communication interface, the scrambling circuit to generate scrambled control codes based on the control data, wherein the control data has a first number of bits, and the scrambler circuit is to generate the scrambled control codes by:
generating, based on the control data and a bit sequence representing the multimedia channel, expanded control codes having a second number of bits that are greater than the first number of bits, and
generating the scrambled control codes based on the expanded control codes and the random numbers;
an encoder circuit to generate transition minimized control codes for transmission via the multimedia channel based on the scrambled control codes; and
a randomizer reset circuit to generate a transition maximized reset code for transmission via the multimedia channel for synchronization of the random number generator with a remote random number generator.
2. The device of claim 1 , wherein the encoding circuit generates the transition minimized control codes further based on a disparity value indicating a disparity between a number of 0's and number of 1's transmitted in one or more previous transition minimized control codes.
3. The device of claim 1 , wherein the encoder circuit generates the transition minimized codes by selecting the transition minimized codes from a plurality of pre-determined transition minimized codes.
4. The device of claim 1 , wherein the control data corresponds to display synchronization information.
5. The device of claim 1 , wherein the control data describes the multimedia data that is to follow the control data.
6. The device of claim 1 , wherein:
in a first mode the device transmits the transition minimized codes via the multimedia channel, and
in a second mode the device transmits transition maximized versions of the control data via the multimedia channel.
7. The device of claim 6 , wherein the device is set to either the first mode or the second mode responsive to a determination by the device that a sink interface to which the device is transmitting multimedia data is capable of receiving transition minimized codes, wherein this determination is made via communications preformed with the sink interface via a display data channel.
8. A device for communications over a multimedia communication interface having a plurality of multimedia channels, comprising:
a random number generator to generate random numbers;
a decoder circuit to decode transition minimized control codes received via a multimedia channel of the plurality of multimedia channels of the multimedia communication interface, the decoding circuit to decode the transition minimized control codes to generate scrambled control codes based on the transition minimized control codes;
a de-scrambler circuit to generate control data associated with multimedia data to be transmitted over the multimedia channel based on the scrambled control codes and the random numbers, wherein the de-scrambler circuit is to generate the control data by:
de-scrambling at least a portion of the scrambled control codes into intermediate control codes having a first number of bits, and
generating the control data having a second number of bits less than the first number of bits based on the intermediate control codes; and
a randomizer reset circuit to detect a transition maximized reset code received via the multimedia channel of the multimedia communication interface, the random number generator being reset responsive to detection of the transition maximized reset code.
9. The device of claim 8 , wherein the decoder circuit generates the scrambled control codes by referencing the transition minimized control codes to a look up table that includes a plurality of pre-determined transition minimized control codes.
10. The device of claim 8 , wherein the control data corresponds to display synchronization information.
11. The device of claim 8 , wherein the control data describes the multimedia data that is to follow the control codes.
12. The device of claim 8 , wherein the transition minimized codes are received in a first mode, and wherein, in a second mode, the device receives transition maximized versions of the control data via the multimedia channel and decodes and de-scrambles the transition maximized versions of the control data.
13. The device of claim 12 , wherein the device communicates an indication via a display data channel that the device is capable of receiving transition minimized codes to a source device from which the multimedia data is being received, wherein the source device is configured to transmit transition minimized codes responsive to this indication.
14. A non-transitory computer readable medium storing a representation of a device for communications over of a multimedia communication interface having a plurality of multimedia channels, the device comprising:
a random number generator to generate random numbers;
a scrambler circuit to receive control data associated with multimedia data to be transmitted over a multimedia channel of the plurality of multimedia channels of the multimedia communication interface, the scrambling circuit to generate scrambled control codes based on the control data, wherein the control data has a first number of bits, and the scrambler circuit is to generate the scrambled control codes by:
generating, based on the control data and a bit sequence representing the multimedia channel, expanded control codes having a second number of bits that are greater than the first number of bits, and
generating the scrambled control codes based on the expanded control codes and the random numbers;
an encoder circuit to generate transition minimized control codes for transmission via the multimedia channel based on the scrambled control codes; and
a randomizer reset circuit to generate a transition maximized reset code for transmission via the multimedia channel for synchronization of the random number generator with a remote random number generator.
15. A non-transitory computer readable medium storing a representation of a device for communications over a multimedia communication interface having a plurality of multimedia channels, the device comprising:
a random number generator to generate random numbers;
a decoder circuit to decode transition minimized control codes received via a multimedia channel of the plurality of multimedia channels of the multimedia communication interface, the decoding circuit to decode the transition minimized control codes to generate scrambled control codes based on the transition minimized control codes;
a de-scrambler circuit to generate control data associated with multimedia data to be transmitted over the multimedia channel based on the scrambled control codes and the random numbers, wherein the de-scrambler circuit is to generate the control data by:
de-scrambling at least a portion of the scrambled control codes into intermediate control codes having a first number of bits, and
generating the control data having a second number of bits less than the first number of bits based on the intermediate control codes; and
a randomizer reset circuit to detect a transition maximized reset code received via the multimedia channel of the multimedia communication interface, the random number generator being reset responsive to detection of the transition maximized reset code.