4.3.2.3 Data Input and Output Bit Frames

Communication with the ECC204-TFLXAUTH is conducted in time intervals referred to as bit frames and lasts t_BIT in duration. Each bit frame contains a single binary data value. Input bit frames are used to transmit data from the host to the ECC204-TFLXAUTH and can either be a logic ‘0’ or a logic ‘1’. An output bit frame carries data from the ECC204-TFLXAUTH to the host. In all input and output cases, the host initiates the bit frame by driving the SI/O line low. Once the ECC204-TFLXAUTH detects the SI/O being driven below the V_IL level for a duration greater than t_{IGNORE_SWI} its internal timing circuits begin to run.

The duration of each bit frame is allowed to vary from bit to bit as long as the variation does not cause the t_BIT length to exceed the specified minimum and maximum values.