ÉlanSC310 Microcontroller Evaluation Board User’s Manual
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Evaluation Board’s Components
8042 Keyboard Controller
The evaluation board uses a non-static 8042 keyboard controller. What this means
to the programmer is that if SysCLK stops being driven to the 8042 for any period
of time, the controller must be reset once SysCLK starts being driven again in order
for the 8042 to function properly. The ÉlanSC310 microcontroller stops driving
SysCLK any time the Low Speed PLL is disabled or when in Sleep, Suspend and
Off PMU modes even if the Low Speed PLL is enabled for these modes. One side
effect of not driving SysCLK to the 8042 is the RC pin from the 8042 will go active
for a short period of time. This active state is latched by the ÉlanSC310
microcontroller. Therefore when the ÉlanSC310 microcontroller goes back to High
Speed PLL mode from Sleep, Suspend or Off mode, the CPU is reset.
Note that the above conditions only apply to a non-static 8042. If a static 8042 is
used, then these conditions don’t apply.
To work around these situations, the evaluation board has been wired to use two
pins on the ÉlanSC310 microcontroller to gate RC from the 8042 (PMC4) and to
reset the 8042 (PMC0). PMC4 should be programmed to mask off the RC pin from
the 8042 while in Sleep, Suspend, and Off modes to prevent the CPU from being
reset due to SysCLK not being driven out of the ÉlanSC310. (If the Low Speed
PLL is to be disabled in Doze mode then PMC4 should be driven for this mode as
well.) When the system goes back to High Speed PLL mode, the 8042 needs to be
reset by pulsing PMC0 high for 1 millisecond. Commands should also be issued
to the 8042 to re-enable the keyboard. See “PMC0” on page 4-4 and “PMC4” on
page 4-4 for more information.
National Super I/O PC87322VF
The Super I/O is set up to decode address 398h and 399h for its index and data
registers.
When configuring the serial port on the Super I/O it is important to note that IRQ3
from the chip is connected to PIRQ0 on the ÉlanSC310 microcontroller. (Note:
PIRQ0 on the ÉlanSC310 is internally set to IRQ3 when in Full ISA Bus mode; it
is programmable in all other bus modes.) IRQ4 from the Super I/O is not connected.
Therefore when configuring the serial port in the Super I/O, only configure it to
use IRQ3. Also PMC2 must be set to 1 in order to enable the RS232 drivers for
the serial port.
evalbd.book : ch4 Page 14 Thursday, August 8, 1996 2:34 PM