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11.
Special functions
The keypad offers some special functions which will be described in the following in a more
detailed way. Please make sure to refer to the corresponding K-Matrix as well, as these
descriptions will just be excerpts of the functionality.
Sleep/Wakeup, Power Saving
To save power, the keypad offers a sleep mode. There is more than one way to set the keypad
into sleep-mode. It can be achieved either through a specific Sleep timer on CAN or by setting
an external hardware signal. Please refer to the K-Matrix to find the object in which the
Sleep/Wakeup source can be chosen and what value stands for which option. If the use of the
sleep mode is not wanted in an application, the user has to make sure that it is configured to
the 2-wire hardware interface mode and the wakeup-in pin is either left open or pulled reliably
to GND.
11.1.1
Sleep/Wakeup over CAN
This function is implemented according to CiA320 for CANopen, for J1939 the protocol is
manufacturer specific on the basis of the CANopen implementation and is specified in the
corresponding K-Matrix.
If the keypad is configured to sleep/ wakeup over CAN it will enter sleep mode if no CAN
message is received for 5 seconds. After that the keypad can be woken up by sending an
arbitrary CAN message (or keep alive message) or by pressing a button. Please refer to the
K-Matrix to see how each button can be configured to enable wakeup or disable it.
The wakeup out pin is disabled in this mode.
11.1.2
Sleep/Wakeup over 2 wire hardware interface
The keypad offers a 2-wire interface to enable Sleep mode. For this it offers a wakeup-in pin
with which the keypad can be set to sleep mode and can be woken up respectively. The pin
can draw between ~2mA and 7,5mA depending on the voltage on the wakeup-in pin.
This pin is read by the microcontroller analogical. After a reset of the keypad the pin needs to
be pulled high to activate the wakeup-in. If this does not happen the port will stay deactivated.
To activate the sleep mode a falling edge must be generated on the pin. The voltage must
switch from high to low. This can be done by switching to a low level or by turning the operating
port on the controlling device to high-z. The voltage must be held at low level to keep the
keypad in sleep mode. To wake the keypad back up the voltage at the wakeup pin must switch
from low to high and must then be held at high to keep the keypad awake.
11-1 circuit diagram Wake-up-in