4.2.2.1.2 Device Response upon Reset or Power-Up
After the device is powered-up or after the host resets the device by holding the SI/O line low for tRESET or tDSCHG, the host must release the line, which will be pulled high by an external pull-up resistor. The host must, then, wait an additional minimum time of tRRT before it can request a Discovery Response Acknowledge from the device.
The Discovery Response Acknowledge sequence begins with the host driving the SI/O line low, which will enable the SHA104-TFLXAUTH internal timing circuits. The host must continue to drive the line low for tDRR.
During the tDRR time, the SHA104-TFLXAUTH will respond by concurrently driving SI/O low. The device will continue to drive SI/O low for a total time of tDACK. The host must sample the state of the SI/O line at tMSDR past the initiation of tDRR. By definition, the tDACK minimum time is longer than the tMSDR maximum time, thereby ensuring the host can always correctly sample the SI/O for a level less than VIL. After the tDACK time elapses, the SHA104-TFLXAUTH will release SI/O, which will, then, be pulled high by the external pull‑up resistor.
The host must, then, wait tHTSS to create a Start condition before continuing with the first command (see Start/Stop Condition for more details about Start conditions).