Z86L88 Datasheet, PDF (29/66 Pages) Zilog, Inc. – INFRARED REMOTE CONTROLLERS

R253 RP
D7 D6 D5 D4 D3 D2 D1 D0
Z86L88/81/86/87/89/73
IR/Low-Voltage Microcontroller
Note: When SPH is used as a general-purpose register
and Port 0 is in address mode, the contents of SPH will be
1 ^{loaded into Port 0 whenever the internal stack is accessed.}
Default Setting After Reset = 0000 0000
Expanded Register
File Pointer
Working Register
Pointer
Figure 22. Register Pointer Register
Register File. The register file (bank 0) consists of four I/O
port registers, 236 general-purpose registers, and 16 con-
trol and status registers (R0-R3, R4-R239, and R240-
R255, respectively), Plus two expanded registers groups
(Banks D and F). Instructions can access registers directly
or indirectly through an 8-bit address field. This allows a
short, 4-bit register address using the Register Pointer
(Figure 23). In the 4-bit mode, the register file is divided
into 16 working register groups, each occupying 16 contin-
uous locations. The Register Pointer addresses the start-
ing location of the active working register group.
Note: Working register group E0-EF can only be access-
ed through working registers and indirect addressing
modes.
Stack. The Z86LXX external data memory or the internal
register file is used for the stack. An 8-bit Stack Pointer
(R255) is used for the internal stack that resides in the gen-
eral-purpose registers (R4-R239). SPH is used as a gen-
eral-purpose register only when using internal stacks.
r7 r6 r5 r4 r3 r2 r1 r0 _R253
The upper nibble of the register file address
provided by the register pointer specifies
the active working-register group
7F
70
6F
60
5F
50
4F
40
3F
Specified Working
Register Group
30
2F
20
1F
Register Group 1
10
0F
Register Group 0
00
I/O Ports
The lower nibble
of the register
file address
provided by the
instruction points
to the specified
register
R15 to R0
R15 to R4 *
R3 to R0 *
Figure 23. Register Pointer
COUNTER/TIMER REGISTER DESCRIPTION
Table 4. Expanded Register Group D
(D)%0C
(D)%0B
(D)%0A
(D)%09
(D)%08
(D)%07
(D)%06
(D)%05
(D)%04
(D)%03
(D)%02
(D)%01
(D)%00
Reserved
HI8
LO8
HI16
LO16
TC16H
TC16L
TC8H
TC8L
Reserved
CTR2
CTR1
CTR0
Register Description
HI8(D)%0B: Holds the captured data from the output of the
8-bit Counter/Timer0. This register is typically used to hold
the number of counts when the input signal is 1.
Field
Bit Position
Description
T8_Capture_HI 76543210
R Captured Data
W No Effect
L08(D)%0A: Holds the captured data from the output of
the 8-bit Counter/Timer0. This register is typically used to
hold the number of counts when the input signal is 0.
Field
Bit Position
T8_Capture_L0 76543210 R
W
Description
Captured Data
No Effect
DS96LV00800
PRELIMINARY
29