Interface and communication protocol for a mobile communication device with a smart battery

1. A method of communicating according to a battery communication protocol between a main processor of a mobile communication device and a battery used by the mobile communication device, wherein the method comprises:

providing a communication interface between the main processor and the battery to provide communication therebetween;

sending a protocol version request packet from the main processor to the battery;

initiating authentication of the battery by the main processor based on a cryptographic algorithm executed by the battery and the main processor, if the battery provides a protocol version response packet to the main processor in response to the protocol version request packet; and

reading a battery ID resistor of the battery to identify a type of the battery, if the battery does not provide a protocol version response packet to the main processor in response to the protocol version request packet.

2. The method of claim 1 , wherein the authentication comprises:

sending a pre-computed battery authentication challenge packet from the main processor to the battery;

generating a battery authentication response at the battery;

sending a battery authentication response packet comprising the battery authentication response from the battery to the main processor; and

comparing the battery authentication response with a pre computed battery authentication response at the main processor to determine if the authentication is successful.

3. The method of claim 2 , wherein if the authentication is successful, the method further comprises:

sending a battery information request packet from the main processor to the battery;

generating a battery information response packet at the battery comprising battery information on operation of the battery; and

sending the battery information response packet from the battery to the main processor.

4. The method of claim 3 , wherein the battery information comprises information for a charge curve of the battery.

5. The method of claim 1 , wherein the protocol version request response packet comprises a battery ID of the battery.

6. The method of claim 1 , wherein the battery comprises a smart battery and when a packet with an unknown code is received at the smart battery, the method further comprises sending the protocol version response packet from the smart battery to the main processor to initiate the authentication.

7. The method of claim 1 , wherein the battery comprises a smart battery and when a packet with a failed error check value is received at the smart battery, the method further comprises sending the protocol version response packet from the smart battery to the main processor to initiate the authentication.

8. The method of claim 1 , wherein the protocol version response packet comprises a protocol version that indicates a version of the battery communication protocol being used by the battery to communicate.

9. The method of claim 1 , further comprising providing the communication interface with protection circuitry for protecting the main processor from electrostatic discharge.

10. The method of claim 9 , wherein the method further comprises configuring the protection circuitry to limit a data rate of the communication interface to approximately 300 bits per second.

11. A non-transitory computer-readable storage medium on which are stored program instructions for a method of communicating according to a battery communication protocol between a main processor of a mobile communication device and a battery used by the mobile communication device, wherein the program instructions are executable by the main processor, and wherein the program instructions are for:

sending a protocol version request packet from the main processor to the battery;

initiating authentication of the battery by the main processor based on a cryptographic algorithm executed by the battery and the main processor, if the battery provides a protocol version response packet to the main processor in response to the protocol version request packet; and

reading a battery ID resistor of the battery to identify a type of the battery, if the battery does not provide a protocol version response packet to the main processor in response to the protocol version request packet.

12. The non-transitory computer-readable storage medium of claim 11 , wherein the authentication comprises:

sending a pre-computed battery authentication challenge packet from the main processor to the battery;

receiving a battery authentication response packet at the main processor sent from the battery, the battery authentication response packet comprising a battery authentication response generated at the battery; and

comparing the battery authentication response with a pre-computed battery authentication response at the main processor to determine if the authentication is successful.

13. The non-transitory computer-readable storage medium of claim 12 , wherein if the authentication is successful, the program instructions are further for:

sending a battery information request packet from the main processor to the battery; and

receiving a battery information response packet at the main processor sent from the battery, the battery information response packet comprising battery information on operation of the battery.

14. The non-transitory computer-readable storage medium of claim 13 , wherein the battery information comprises information for a charge curve of the battery.

15. The non-transitory computer-readable storage medium of claim 11 , wherein the protocol version response packet comprises a battery ID of the battery.

16. The non-transitory computer-readable storage medium of claim 11 , wherein the battery comprises a smart battery and when a packet with an unknown code is received at the smart battery, the program instructions are further for receiving the protocol version response packet at the main processor sent from the smart battery to initiate the authentication.

17. The non-transitory computer-readable storage medium of claim 11 , wherein the battery comprises a smart battery and when a packet with a failed error check value is received at the smart battery, the program instructions are further for receiving the protocol version response packet at the main processor sent from the smart battery to initiate the authentication.

18. A method of communicating according to a battery communication protocol between a main processor of a mobile communication device and a battery used by the mobile communication device, wherein the method comprises:

providing a communication interface between the main processor and the battery to provide communication therebetween;

sending a protocol version request packet from the main processor to the battery;

initiating authentication of the battery by the main processor, if the battery provides a protocol version response packet to the main processor in response to the protocol version request packet; and

reading a battery ID resistor of the battery, if the battery does not provide a protocol version response packet to the main processor in response to the protocol version request packet;

wherein the protocol version response packet comprises a protocol version that indicates a version of the battery communication protocol being used; and

wherein the protocol version comprises a minor version number and the method further comprises increasing the minor version number for each backwards-compatible change.

19. The method of claim 18 , wherein the protocol version comprises a major version number and the method further comprises increasing the major version number for each change that is not backwards-compatible.

20. The method of claim 19 , further comprising resetting the minor version number to zero when the major version number is increased.