I2C Time-out

A time-out feature on an I^ 2C interface can be used to detect a “stuck” bus and potentially do something to alleviate the condition. Two different types of time-out are supported. Both types apply whenever the I^ 2C block and the time-out function are both enabled, Master, Slave, or Monitor functions do not need to be enabled.

In the first type of time-out, reflected by the EVENTTIMEOUT flag in the STAT register, the time between bus events governs the time-out check. These events include Start, Stop, and all changes on the I^ 2C clock (SCL). This time-out is asserted when the time between any of these events is longer than the time configured in the TIMEOUT register. This time-out could be useful in monitoring an I^ 2C bus within a system as part of a method to keep the bus running of problems occur.

The second type of I^ 2C time-out is reflected by the SCLTIMEOUT flag in the STAT register. This time-out is asserted when the SCL signal remains low longer than the time configured in the TIMEOUT register. This corresponds to SMBus time-out parameter T_ TIMEOUT. In this situation, a slave could reset its own I^ 2C interface in case it is the offending device. If all listening slaves (including masters that can be addressed as slaves) do this, then the bus will be released unless it is a current master causing the problem. Refer to the SMBus specification for more details.

Both types of time-out are generated when the I^ 2C bus is considered busy.


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