Systems and methods for asynchronous toggling of I2C data line
A method of operating an I2C slave having an I2C clock pin and an I2C data pin is disclosed. The method includes (a) receiving a command via the I2C clock pin and the I2C data pin, (b) driving the I2C data pin to logic low for a first duration, (c) not driving the I2C data pin to logic low for a second duration, and (d) repeatingly alternating (b) and (c) until a termination event occurs. (b) and (c) are not synchronized to transitions of the I2C clock pin. Other methods and systems are disclosed.
1. An I2C slave having an I2C clock pin and an I2C data pin, the I2C slave is configured to receive a command at the I2C clock pin and the I2C data pin and in response repeatedly toggle the I2C data pin until the I2C slave detects the occurrence of a termination event, wherein the toggling is asynchronous to the I2C clock pin, also having a duty cycle register wherein the I2C slave is configured to perform the toggling at a duty cycle proportional to a value in the duty cycle register, and an analog-to-digital converter having an analog input and a digital output and the duty cycle register is coupled to the digital output.
2. The I2C slave of claim 1 , wherein the termination event is the I2C clock pin transitions to logic low from logic high.
3. The I2C slave of claim 1 , wherein the termination event is the I2C clock pin is logic low.
4. The I2C slave of claim 1 , wherein the command includes a frequency value and the I2C slave is configured to perform the toggling at a frequency specified by the frequency value.
5. The I2C slave of claim 1 , wherein the termination event is the toggling has exceeded a maximum duration and the command includes a value of the maximum duration.
6. The I2C slave of claim 1 , wherein the termination event is the toggling has exceeded a maximum number of logic level transitions and the command includes a value of the maximum number of transitions.
7. An I2C slave having a power pin, an I2C clock pin, and an I2C data pin, the I2C slave is configured to be powered via the power pin and to receive a command transmitted via I2C using the I2C clock pin and the I2C data pin then repeatedly toggle the I2C data pin until the power pin is de-energized, wherein the toggling is asynchronous to the I2C clock pin, also having a duty cycle register wherein the I2C slave is configured to perform the toggling at a duty cycle proportional to a value in the duty cycle register, and an analog-to-digital converter and the duty cycle register is coupled to an output of the analog-to-digital converter.
8. The I2C slave of claim 7 , wherein the command includes a frequency value and the I2C slave is configured to perform the toggling at a frequency specified by the frequency value.
9. An I2C device having an I2C clock pin, an I2C data pin, and an input pin, the I2C device is configured to respond to receiving an I2C command via the I2C clock pin and the I2C data pin by alternating between driving the I2C data pin to logic low and not driving the I2C data pin to logic low until the I2C device detects a termination event, wherein the alternating is not synchronized to transitions of the I2C clock pin, also having a duty cycle register wherein the I2C slave is configured to perform the alternating at a duty cycle proportional to a value in the duty cycle register, and an analog-to-digital converter having an analog input and a digital output and the duty cycle register is coupled to the digital output.
10. The I2C device of claim 9 , wherein the termination event is the I2C clock pin transitions to logic low.
11. The I2C device of claim 9 , wherein the termination event is the I2C clock pin is logic low.
12. The I2C device of claim 9 , wherein the command includes a frequency value and the I2C slave is configured to perform the alternating at a frequency corresponding to the frequency value.
13. The I2C device of claim 9 , wherein the termination event is the alternating has exceeded a maximum duration and the command includes a value corresponding to the maximum duration.
14. The I2C device of claim 9 , wherein the termination event is the alternating has exceeded a maximum number of transitions and the command includes a value corresponding to the maximum number of transitions.