Kontron SMARC Evaluation Carrier - Manual (Page 35)

User’s Guide
35 www.kontron.com
8 Push Button Switches
8.1 SW1 Reset Switch
Switch SW1, if pressed, forces the SMARC Module RESET_IN# (Module connector J40 pin P127) signal to GND. It also
forces the I/O Module J66 pin 66 to GND.
The switch does nothing else, and does not issue a general reset signal to the Evaluation Carrier. It is just a signal to
the Module that the user is requesting a reset. The Module processes this and the Module in turn may force the ULP-
COM RESET_OUT# line low (Module connector J40 pin P127).
There is no de-bouncing of SW1 on the Eval Carrier. This happens on the Module. If the SW1 switch is not being pressed,
then the RESET_IN# line floats on the Carrier and is pulled up on the Module.
8.2 SW2 Power On Switch
Switch SW2 is the power button input to the SMARC module from the carrier board (POWER_BTN#: pin P128 of J40). If
pressed, it forces POWER_BTN# signal to GND.
The switch only powers ON the module, it does not power the carrier. The carrier does not have a pull up on this signal
and remains in the float state when the switch is released. The signal should be pulled up in the module.
De-bouncing circuitry is not provided for SW2 in the carrier.
8.3 SW3 Force Recovery Switch
Switch SW3 gives the Force recovery input to the SMARC module (FORCE_RECOV# Pin S155 of J40). If pressed, it
asserts FORCE_RECOV# signal to GND.
Low on this pin allows non-protected segments of Module boot device to be rewritten / restored from an external USB
Host on Module USB0. For SOCs that do not implement USB based Force Recovery functions, a low on the Module
FORCE_RECOV# pin may invoke the SOC native Force Recovery mode – such as over a Serial Port.
If the switch is not being pressed, then the FORCE_RECOV# line floats on the Carrier and is pulled up on the Module. De-
bouncing circuitry is not provided for SW3 in the carrier.