Specifications
WA_DEV_FEX20_PTS_004 Rev 001 June 30, 2010 31
5. Signals and Indicators
5.1. Reset Signal (~RESET)
This pin is tied to the internal reset pin of the Fastrack Xtend. It is used to force a reset procedure by
providing the Expansion Card with a LOW level for at least 200µs. This signal must be considered as
an emergency reset only. A reset procedure is already driven by the internal hardware during the
power-up sequence.
This signal may also be used to provide a reset to an external device (at power-ON only). If no
external reset is necessary, this input may be left open. If used (emergency reset), it must be driven
either by an open collector or an open drain.
The Expansion Card remains in reset mode as long as the ~RESET signal is held LOW.
Note that an operating system reset is preferred to a hardware reset.
Caution: This signal should only be used for “emergency” resets.
5.1.1. Reset Sequence
To activate the “emergency” reset sequence, the ~RESET signal has to be set to LOW for a minimum
of 200s. As soon as the reset is completed, the AT interface answers the application with an “OK”.
Figure 9. Reset Sequence Waveform
At power-up, the ~RESET time (Rt) is carried out after switching the Fastrack Xtend ON. It is
generated by the internal voltage supervisor.
The ~RESET time is provided by the internal RC component. To keep the same time, it is not
recommended to connect another R or C component (resistor or capacitor) on the ~RESET signal.
Only a switch or an open drain gate is recommended.
Ct is the cancellation time required for Fastrack Xtend initialization. Ct is automatically carried out
after hardware reset.
5.1.2. Pin Description
Refer to the following table for the pin description of the reset signal.