Freescale Semiconductor KIT33912EVME, Setup Instructions

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KIT33912EVME System Basis Chip with LIN Tranceiver Setup Instructions, Rev. 2.0
12 Freescale Semiconductor
Figure 3-2. Control/Status Array
3.5 Pulse Width Modulation
The Pulse Width Modulation serves to directly control the High Side and the Low Side Switch Drivers. The operating pulses have
an adjustable frequency from 1Hz to 1MHz. In the highest frequencies adjustment isn’t precise. A frequency change is possible
by dragging the blue frequency bar, with the range of the bar selectable by a drop down menu. Each following range has a scale
one order higher. Width of the duty cycle is adjustable by percentage via the blue duty blue bar, with a minimum step five percent
adjustment. For a zero percentage the Pulse Width Modulation terminal is permanently low, and for a hundred percent the
terminal is high. See
Figure 3-3 .
Figure 3-3. Pulse Width Modulation Control Panel
3.6 Watchdog Service
In the SBCLIN device a watchdog pin is included, which is a configuration terminal for the internal watchdog. When the pin is
directly connected to the ground (place JP1, JP2), this terminal disables the watchdog function. When this terminal is left open
(move JP2), the watchdog period is fixed to its default value of 150ms. If the on-board resistor is connected (place JP2, move
JP1) to this terminal, then it configures the watchdog period to 16ms.
If the on-board watchdog resistor is connected and the GUI is started or a reset condition passes watchdog servicing is activated
automatically; see
Figure 3-4 .
The user can extend the watchdog clear process by selecting the WDx bits in the Timing Control Register, then the button labelled
16 ms redisplays with the relevant clearing time. This configuration is valid only if the windowing watchdog is active.
The user can stop the watchdog servicing by clicking the button labelled 16 ms , which means the watchdog counter is not
properly cleared while it’s window is open for clears, and the MC33912 device will reset the microcontroller. The same sequence
of events will occur, if the user disables the watchdog service by clicking the button labelled
WD ON .
When there is a direct connection of the watchdog terminal to the ground, the watchdog service is disabled automatically.