EVAL-ADUC836QS AD [Analog Devices], EVAL-ADUC836QS Datasheet - Page 15

• Manufacturer Part Number: EVAL-ADUC836QS
• Description: MicroConverter, Dual 16-Bit ADCs with Embedded 62 kB Flash MCU
• Manufacturer: AD [Analog Devices]

Stack Pointer (SP and SPH)
The SP SFR is the stack pointer and is used to hold an internal
RAM address that is called the “top of the stack.” The SP Reg is ter
is incremented before data is stored, during PUSH and CALL
executions. While the Stack may reside anywhere in on-chip RAM,
the SP Register is initialized to 07H after a reset. This causes the
stack to begin at location 08H.
As mentioned earlier, the ADuC836 offers an extended 11-bit
stack pointer. The three extra bits that make up the 11-bit stack
point er are the 3 LSBs of the SPH byte located at B7H.
Program Status Word (PSW)
The PSW SFR contains several bits refl ecting 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
Power Control SFR (PCON)
The PCON SFR contains bits for power saving options and
general-purpose status fl ags, as shown in Table II.
The TIC (Wake-Up/RTC timer) can be used to accurately wake
up the ADuC836 from power-down at regular intervals. To use
the TIC to wake up the ADuC836 from power-down, the OSC_PD
bit in the PLLCON SFR must be clear and the TIC must be
enabled.
SFR Address
Power-On Default Value
Bit Addressable
REV. 0
AC
Table I. PSW SFR Bit Designations
Name
CY
F0
RS1
RS0
OV
F1
P
Description
Carry Flag
Auxiliary Carry Flag
General-Purpose Flag
Register Bank Select Bits
RS1
0
0
1
1
Overfl ow Flag
General-Purpose Flag
Parity Bit
D0H
00H
Yes
87H
00H
No
RS0
0
1
0
1
Selected Bank
0
1
2
3
–15–
Bit
7
6
5
4
3
2
1
0
ADuC836 CONFIGURATION SFR (CFG836)
The CFG836 SFR contains the necessary bits to confi gure the
internal XRAM and the extended SP. By default it con fi g ures
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. If this bit is set, the in-
ALEOFF
Name
SMOD
SERIPD
INT0PD
GF1
GF0
PD
IDL
Table III. CFG836 SFR Bit Designations
Table II. PCON SFR Bit Designations
Description
Extended SP Enable. If this bit is set, the
stack will roll over from SPH/SP = 00FFH to
0100H. If this bit is clear, the SPH SFR will
be dis abled and the stack will roll over from
SP = FFH to SP = 00H.
Reserved for Future Use
Reserved for Future Use
Reserved for Future Use
Reserved for Future Use
Reserved for Future Use
Reserved for Future Use
ternal XRAM will be mapped into the lower
2 Kbytes of the external address space. If this
bit is clear, the internal XRAM will not be
accessible and the external data memory will
be mapped into the lower 2 Kbytes of external
data memory (see Figure 3).
Description
Double UART Baud Rate
SPI Power-Down Interrupt Enable
Disable ALE Output
General-Purpose Flag Bit
General-Purpose Flag Bit
Power-Down Mode Enable
Idle Mode Enable
Power-Down Interrupt Enable
AFH
00H
No
ADuC836