ADUC844 Analog Devices, ADUC844 Datasheet - Page 15

• Manufacturer Part Number: ADUC844
• Description: MicroConverter/ Dual 16-Bit/24-Bit ADCs with Embedded 62kB FLASH MCU
• Manufacturer: Analog Devices

EXSP (CFG844.7) bit must be set otherwise the SPH SFR cannot be
read or written to.
Program Status Word (PSW)
The PSW SFR contains several bits reflecting the current status of the
CPU as detailed in Table I.
SFR Address
Power ON Default Value
Bit Addressable
Bit
7
6
5
4
3
2
1
0
The PCON SFR contains bits for power-saving options and general-
purpose status flags as shown in Table II.
SFR Address
Power ON Default Value
Bit Addressable
Bit
7
6
5
4
3
2
1
0
REV. PrB
Name
CY
AC
F0
RS1
RS0
OV
F1
P
Name
SMOD
SERIPD
INT0PD
ALEOFF Disable ALE Output
GF1
GF0
PD
IDL
Table II. PCON SFR Bit Designations
Table I. PSW SFR Bit Designations
Description
Carry Flag
Auxiliary Carry Flag
General-Purpose Flag
Register Bank Select Bits
RS1
0
0
1
1
Overflow Flag
General-Purpose Flag
Parity Bit
Description
Double UART Baud Rate
SPI Power-Down Interrupt Enable
INT0 Power-Down Interrupt Enable
General-Purpose Flag Bit
General-Purpose Flag Bit
Power-Down Mode Enable
Idle Mode Enable
RS0
0
1
0
1
PRELIMINARY TECHNICAL DATA
Selected Bank
0
1
2
3
D0H
00H
Yes
87H
00H
No
-15-
The CFG844 SFR contains the necessary bits to configure the
internal XRAM and the extended SP. By default it configures the
user into 8051 mode. i.e. extended SP is disabled, internal XRAM is
disabled.
SFR Address
Power ON Default Value
Bit Addressable
Bit
7
6
5
4
3
2
1
0
Name
EXSP
XRAMEN XRAM Enable Bit
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Table III. CFG844 SFR Bit Designations
Description
Extended SP Enable
If this bit is set then the stack will
rollover from SPH/SP = 00FFh to
0100h.
If this bit is clear then the SPH SFR will be
disabled and the stack will rollover from SP=FFh to
SP =00h
If this bit is set then the internal
XRAM will be mapped into the lower
2kBytes of the external address space.
If this bit is clear then the internal
XRAM will not be accessible and the
external data memory will be mapped
into the lower
memory. (see figure 3)
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----
----
----
----
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AFhH
00H
No
2kBytes of external data
ADuC844