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9-34 SA-1100
Developer’s Manual
System Control Module
9.5.7.2 Power Manager General Configuration Register (PCFR)
The PCFR contains bits used to configure various functions within the SA-1100. The OPDE bit, if
set, allows the 3.6864-MHz oscillator to be disabled during sleep mode. This bit is cleared on the
assertion of nRESET. The FP and FS bits control the state of the PCMCIA control pins and the
static memory control pins during sleep. The following table shows the bit-field definitions for this
register. The FO bit forces the SA-1100 to assume that the 32-kHz oscillator is stable instead of
waiting for the requisite 2–10 seconds using an internal counter. This function is primarily useful
for "warm" hardware resets where the oscillator is already stable when the processor comes out of
reset.
Bit31302928272625242322212019181716
R/W Reserved
Reset0000000000000000
Bit1514131211109876543210
R/W Reserved FO FS FP
OPD
E
Reset0000000000000000
Bit Name Description
0OPDE
3.6864-MHz oscillator power-down enable.
0 – Do not stop the oscillator during sleep mode (reset condition).
1 – Stop the 3.6-MHz oscillator during sleep mode.
1FP
Float PCMCIA controls during sleep mode.
This bit determines whether the PCMCIA control signals are driven to a high (negated)
state during sleep or not driven (floated). A zero indicates that the pins are driven low. A
one indicates that they will be floated. This bit is zero at hardware reset. The PCMCIA
signals affected by this bit are: nPOE, nPWE, nPIOW, nPIOR, nPCE<2:1>, nIOIS16,
and nPWAIT. PSKSEL and nPREG are derived from address signals and assume the
state of the address bus during sleep.
2FS
Float static chip selects during sleep mode.
This bit determines whether the static chip select control signals are driven to a high
during sleep or floated. A zero indicates that the pins are driven low. A one indicates that
they will be floated. The static chip select signals affected by this bit are: nCS<3:0>,
nOE, and nWE. This bit is zero at hardware reset.
3FO
Force 32-kHz oscillator enable on.
This bit is used to allow software to force the SA-1100 to use the 32-kHz oscillator for
internal clocking functions instead of waiting for it to stabilize in the normal way. This
function is
useful primarily to attain rapid functionality after a "warm" hardware reset when it is
known that the oscillator is stable. Use of this bit is intended for test purposes and
some
customer use in special situations. It should be used with care, however, since setting
this bit when the 32-kHz oscillator is not stable will yield unpredictable results.
31..4 — Reserved.