Notes:
1. The shared graphics controller interface and VESA local bus pins:
These signals default to three-state with pulldown resistors and remain this way until an LCD or VL-bus interface is selected
(all except LVEE and LVDD).
When the graphics controller is enabled on the ÉlanSC400 microcontroller, the signals will be three-state with pulldowns
whenever the LCD is not enabled. This allows the LCD to be powered off in any mode, and prevents damage to the LCD by
having it powered when the timing of the signals is not correct. In Suspend these signals are three-state with pulldowns. The
LCD cannot be driven in Suspend.
When the VESA local bus interface is enabled, the signals will become the inputs and outputs necessary for VL-bus support.
In Suspend, the signals support leaving the VL device powered on or off (Power-Down Group F).
Summary: LCD control signals/VESA local bus control signals (all except LVEE and LVDD) have built-in pulldown resistors
that are invoked by:
–Reset invokes pulldowns.
–Graphics controller disabled and VL-bus disabled invokes pulldowns.
–VL-bus enabled and VL interface programmed for power-down in Suspend mode invokes pulldowns (Power-Down Group F).
–Graphics controller enabled and LCD enabled. All pins are outputs with no termination.
–Graphics controller enabled and LCD disabled. All pins are three-state with pulldowns.
–VL-bus enabled and not Suspend mode. No pulldowns enabled.
Summary: LVEE and LVDD have built-in pullup and pulldown resistors that are invoked by:
–Reset invokes pullups.
–VL-bus enabled and VL interface programmed for power-down in Suspend mode invokes pulldowns in Suspend mode
(Power-Down Group F).
–Graphics enabled. Drive out High in Suspend.
–Graphics enabled. Both pins are outputs without pullups or pulldowns.
–VL-bus enabled. No pullups or pulldowns in normal operation.
2. The graphics controller signals LCDD7–LCDD0, M, LC, SCK, FRM, LVEE, and LVDD are not supported on the ÉlanSC410
microcontroller.
Élan™SC400 and ÉlanSC410 Microcontrollers Data Sheet
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AMD [ AMD ]
