W77C32/W77C032A
SBUF1.7-0: Serial data of the serial port 1 is read from or written to this location. It actually consists of
two separate 8-bit registers. One is the receive resister, and the other is the transmit
buffer. Any read access gets data from the receive data buffer, while write accesses are
to the transmit data buffer.
ROMMAP
Bit:
7
WS
Mnemonic: ROMMAP
WS:
6
1
5
-
4
-
3
-
2
-
1
-
0
-
Address: C2h
Wait State Signal Enable. Setting this bit enables the
WAIT
signal on P4.0. The
device will sample the wait state control signal
WAIT
via P4.0 during MOVX
instruction. This bit is time access protected
Bit:
7
CD1
6
CD0
5
SWB
4
-
3
XTOFF
2
ALE-OFF
Power Management Register
1
-
0
DME0
Mnemonic: PMR
Address: C4h
CD1, CD0: Clock Divide Control. These bit selects the number of clocks required to generate one
machine cycle. There are three modes including divide by 4, 64 or 1024. Switching
between modes must first go back devide by 4 mode. For instance, to go from 64 to 1024
clocks/machine cycle the device must first go from 64 to 4 clocks/machine cycle, and then
from 4 to 1024 clocks/machine cycle.
CD1,
0
0
1
1
SWB:
CD0
0
1
0
1
Clocks/machine cycle
Reserved
4
64
1024
Switchback Enable. Setting this bit allows an enabled external interrupt or serial port activity
to force the CD1,CD0 to divide by 4 state (0,1). The device will switch modes at the start of
the jump to interrupt service routine while a external interrupt is enabled and actually
recongnized by microcontroller. While a serial port reception, the switchback occurs at the
start of the instruction following the falling edge of the start bit.
XTOFF: Crystal Oscillator Disable. Setting this bit disables the external crystal oscillator. This bit can
only be set to 1 while the microcontroller is operating from the RC oscillator. Clearing this bit
restarts the crystal oscillator, the XTUP (STATUS.4) bit will be set after crystal oscillator
warmed-up has completed.
ALEOFF: This bit disables the expression of the ALE signal on the device pin during all on-board
program and data memory accesses. External memory accesses will automatically enable
ALE independent of ALEOFF.
0 = ALE expression is enable;
DME0:
1 = ALE expression is disable
This bit determines the on-chip MOVX SRAM to be enabled or disabled.
Set this bit to 1 will enable the on-chip 1KB MOVX SRAM.
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Publication Release Date: February 1, 2007
Revision A8
WINBOND [ WINBOND ]
