Power charging of mobile devices via a HDMI interface
A method is provided of charging a mobile device by a charger device, comprising transmitting and receiving a charging current via the Hot Plug Detect (HPD) pin of an HDMI cable connected between the mobile device and the charging device. The HDMI source device (the mobile device) and the HDMI sink device (the charger device) are also provided.
1. A method comprising:
determining, at a high-definition multimedia interface (HDMI) source, if an HDMI sink is configured to use a Hot Plug Detect (HPD) pin for charging; and
if the HDMI source determines that the HDMI sink is configured to use the HPD pin for charging, connecting a battery of the HDMI source to the HPD pin of the HDMI source to receive a charging current via the HPD pin of the HDMI source;
wherein the HDMI sink is determined to be configured to use the HPD pin for charging when at least one of Extended Display Identification Data (EDID) and Enhanced Extended Display Identification Data (E-EDID) is available for reading, the voltage on the HPD is in the range of 4.75V-5.25V, and up to 500 mA of current is available on the HPD pin.
2. A method according to claim 1 , wherein the charging current is transmitted by the HDMI sink and received by the HDMI source.
3. A method according to claim 1 , further comprising determining, by the HDMI sink, a desired charging condition needed by the HDMI source for charging.
4. A method according to claim 3 , further comprising providing, by the HDMI source, information about the desired charging condition of the HDMI source using at least one of a DDC message, a CEC message, and a CDC message.
5. A method according to claim 4 , wherein the information about the desired charging condition is a single byte representing a multiple of a unit of charging current.
6. A method according to claim 4 , further comprising detecting, by the HDMI source, a voltage level on the HPD pin to determine that the HDMI sink is applying a charging voltage, and if so, awaiting acknowledgement that the HDMI sink has received information about the desired charging condition before using the HPD pin for charging.
7. An apparatus comprising:
a high-definition multimedia interface (HDMI) source having:
a Hot Plug Detect (HPD) pin;
a voltage level detector coupled to the HPD pin;
a switch coupled between a battery charge circuit and the HPD pin, the switch being configured to selectively couple the HPD pin to the battery charge circuit; and
a battery coupled to the battery charge circuit; and
a Display Data Channel (DDC) master circuit;
wherein the HDMI source is configured to detect if charging current can be drained from the HPD pin and to detect readability of at least one of Extended Display Identification Data (EDID) and Enhanced Extended Display Identification Data (E-EDID) via the DDC master circuit and, if charging current on the HPD pin can be drained from the HPD pin and the readability of the at least one of EDID and E-EDID is detected, await acknowledgement that a corresponding HDMI sink has received information about a desired charging condition before using the HPD pin to charge the battery.
8. An apparatus as claimed in claim 7 comprising a mobile device.
9. An apparatus according to claim 7 , wherein the apparatus is adapted to use the charging current to at least one of charge the battery of the HDMI source and power applications running on the HDMI source.
10. An apparatus according to claim 7 , wherein, the voltage level detector is configured to detect a voltage on the HPD pin and to determine if the voltage falls within a range suitable for charging.
11. An apparatus according to claim 10 , wherein the range suitable for charging is between 4.75V to 5.25V, inclusive.
12. An apparatus according to claim 10 comprising messaging circuitry for providing information about the desired charging condition using at least one of a DDC message, a CEC message, and a CDC message of an HDMI system.
13. An apparatus comprising:
an HDMI (high-definition multimedia interface) sink having:
a Hot Plug Detect (HPD) pin;
a 5V power supply coupled to the HPD pin; and
a Data Display Channel (DDC) line;
wherein the HDMI sink is configured to apply a charging current on the HPD pin when at least one of Extended Display Identification Data (EDID) and Enhanced Extended Display Identification Data (E-EDID) is available for reading via the DDC line and information about a desired charging condition of a corresponding HDMI source has been received using at least one of a DDC message, a CEC message, and a CDC message of an HDMI system, and to provide an acknowledgement of receipt of the information.
14. An apparatus according to claim 13 , comprising a charging device.
15. An apparatus according to claim 13 , wherein the HDMI sink is adapted to provide charging current of up to 500 mA at a voltage of between 4.75V and 5.25V, inclusive.
16. An apparatus according to claim 13 , wherein the 5V power supply is adapted to supply at least 20 mA to the HPD pin for enabling pre-charging of the HDMI source.
17. The apparatus of claim 16 wherein:
the HDMI sink is configured to determine if a battery of the HDMI source is completely discharged and, if the battery of the HDMI source is determined to be completely discharged, transmit a fixed current on the HPD pin of the HDMI sink from the HDMI sink.
18. The apparatus of claim 17 wherein the fixed current is at least 20 mA and has a voltage of 5V.