Single pin communication mechanism
A method and device include a power pin, a ground pin, and a communications pin. A communications module receives power from the power pin and utilizes an edge counting communication protocol over the communication pin.
1. A battery pack comprising:
a battery; and
a communication chip coupled to the battery, the communication chip including:
a communication pin to couple the communication chip to another device to exchange data;
a communication circuit coupled to the communication pin, and to detect and count pulses serially received or transmitted on the communication pin corresponding to a wake token, a zero token and a one token, wherein the zero token comprises a first low pulse occurring for a start period, followed by a first high pulse occurring for a high period, followed by a second low pulse occurring for a low period, and wherein the one token comprises the second low pulse followed by a second high pulse that is sent after the start period, and wherein the communication circuit uses pulse counts to transfer data;
a memory containing secret data and a serial number of the battery pack;
a command circuit to perform cryptographic calculations utilizing the secret data to authenticate the battery pack, wherein the command circuit is coupled to the communication circuit to receive commands and provide data responsive to such commands; and
a third circuit to assemble zero and one tokens into one or more bytes for providing responses verifying proper command executions, including one of
cryptographically calculated data based on the secret data,
cryptographically calculated data based on a received digest, or
cryptographically calculated data based on a customer identification data.
2. The battery pack of claim 1 , further comprising a protected nonvolatile memory containing the secret data.
3. The battery pack of claim 1 , wherein the command circuit enters into a sleep state if the command circuit detects a leading edge transition and does not receive a token after a timeout interval.
4. The battery pack of claim 1 , wherein the communication circuit utilizes a single communication channel to communicate.
5. The battery pack of claim 1 , wherein the communication pin is coupled to a communication line coupled to a host.
6. The battery pack of claim 1 , wherein the communication circuit functions to receive the wake token, the zero token and the one token.
7. The battery pack of claim 1 , wherein bits are formed by one or more transitions from a high voltage level to a low voltage level or from a low voltage level to a high voltage level.
8. The battery pack of claim 1 , wherein the wake token comprises a pulse having a leading edge or trailing edge transitioning from a high voltage level to a low voltage level or from a low voltage level to a high voltage level.
9. The battery pack of claim 1 , further comprising a power pin to receive power.
10. The battery pack of claim 1 , wherein the battery pack is configured for receiving power from the communication pin.
11. The battery pack of claim 1 , wherein the communication chip further comprises a wake module that receives wake tokens that initiate waking up the communication chip and enables the communication circuit to receive the zero and one tokens.
12. The battery pack of claim 1 , wherein the communication chip further comprises a watchdog counter operable to place the communication chip into a sleep mode.
13. The battery pack of claim 1 , wherein the communication chip assembles bytes of data into blocks of data including a CRC for the block.