Two-wire link for time-multiplexed power and data transmission to multiple devices

1. An apparatus comprising:

a first terminal and a second terminal to be coupled to a host via a first wire and a second wire, respectively;

a third terminal and a fourth terminal operable to couple to a second apparatus via a third wire and a fourth wire, respectively;

a first switch to selectively couple the first terminal and the third terminal, wherein the second terminal and the fourth terminal are coupled;

a rechargeable storage; and

a data circuitry,

wherein the apparatus is to:

during a first time-period, receive power via the first wire and the second wire from the host, and store the power in the rechargeable storage, and

during a second time-period, transmit data from the data circuitry to the host via the first wire and the second wire,

wherein the first and second time-periods are non-overlapping time periods, and

wherein the apparatus is to refrain from transmitting any data to, or receiving any data from, the host during the first time period.

2. The apparatus of claim 1 , wherein the apparatus is to refrain from receiving any power from the host during the second time period.

3. The apparatus of claim 1 , further comprising:

a second switch coupled between the rechargeable storage and the first terminal; and

a third switch coupled between the data circuitry and the first terminal.

4. The apparatus of claim 3 , wherein the apparatus is to:

during the first time-period, close the second switch to receive power in the rechargeable storage and open the second and third switches.

5. The apparatus of claim 3 , wherein the apparatus is to:

during the second time-period, close the third switch to transmit data from the data circuitry to the host, and open the first and second switches.

6. The apparatus of claim 3 , wherein the apparatus is to:

during a third time-period, open the second and third switches and close the first switch, to allow the host to transmit power to the second apparatus and receive data from the second apparatus via the first apparatus.

7. The apparatus of claim 6 , wherein the apparatus is to:

during a fourth time-period, open the first, second and third switches, and discharge the rechargeable storage.

8. The apparatus of claim 3 , further comprising:

a state machine to control operation of the first, second and third switches.

9. The apparatus of claim 1 , wherein the apparatus is to:

during a third time-period, forward power from the host to a second apparatus; and

during a fourth time-period, forward data from the second apparatus to the host.

10. A system comprising:

a memory to store instructions;

a processor coupled to the memory, the processor to execute the instructions; and

a controller coupled to one or both the processor or the memory, wherein the controller is to:

transmit, over a first wire and a second wire, power to a plurality of devices, and

receive, over the first wire and the second wire, data from the plurality of devices,

wherein the controller is to time multiplex the transmission of the power and the reception of the data,

wherein the controller is to refrain from transmitting power while receiving data, and refrain from receiving data while transmitting power, and

wherein the controller is to ground the first and second wire for at least a threshold period of time, to signal the plurality of devices to discharge any energy stored in the plurality of devices.

11. The system of claim 10 , wherein the system comprises:

a wireless interface to allow the processor to communicate with another system,

wherein the memory is to store the data received from the plurality of devices.

12. The system of claim 10 , wherein the plurality of devices comprises:

a first device coupled to the controller using the first wire and the second wire;

a second device coupled to the first device using a third wire and a fourth wire, the controller coupled to the second device via the first device; and

a third device coupled to the second device using a fifth wire and a sixth wire, the controller coupled to the third device via the first and second devices.

13. The system of claim 12 , wherein the controller is to:

during a first time-period, transmit power to the first device over the first and second wires;

during a second time-period occurring subsequent to the second time-period, receive first data from the first device over the first and second wires;

during a third time-period occurring subsequent to the second time-period, transmit power to the second device over the first and second wires; and

during a fourth time-period occurring subsequent to the third time-period, receive second data from the second device over the first and second wires,

wherein the first, second, third, and fourth time period are non-overlapping time periods.

14. The system of claim 13 , wherein the controller is to:

during a fifth time-period occurring subsequent to the fourth time-period, transmit power to the third device over the first and second wires; and

during a sixth time-period occurring subsequent to the fifth time-period, receive third data from the third device over the first and second wires.

15. The system of claim 10 , wherein the system is to be coupled to the plurality of devices over a communication link consisting of the first wire and the second wire, wherein the second wire is to be coupled to a ground terminal.

16. A method comprising:

receiving, by a first device and during a first time-period, power over a first link and a second link from a host;

pre-charging, by the first device and during a first time-period, a battery using power received over the first link and the second link from the host;

transmitting, by the first device and during a second time-period, first data over the first link and the second link to the host;

forwarding, by the first device and during a third time-period, power from the host to a second device; and

forwarding, by the first device and during a fourth time-period, second data from the second device to the host,

wherein the first, second, third and fourth time periods are consecutive and non-overlapping time periods.

17. The method of claim 16 , wherein forwarding power from the host to the second device comprises:

receiving, by the first device and during the third time-period, power over the first link and the second link from the host; and

transmitting, by the first device and during the third time-period, power over a third link and a fourth link to the second device.

18. The method of claim 17 , wherein forwarding the second data from the second device to the host comprises:

receiving, by the first device and during the fourth time-period, the second data over the third link and the fourth link from the second device; and

transmitting, by the first device and during the fourth time-period, the second data over the first link and the second link to the host.