z86l88 ZiLOG Semiconductor, z86l88 Datasheet - Page 27

• Manufacturer Part Number: z86l88
• Description: Low-voltage Ir Microcontroller
• Manufacturer: ZiLOG Semiconductor

PS024102-0804
Note:
16 banks with 16 registers per bank. These register groups are known as the
Expanded Register File (ERF). Bits 7–4 of register RP select the working register
group. Bits 3–0 of register RP select the expanded register file bank.
The upper nibble of the register pointer (Figure 12 on page 22) selects which
working register group is accessed of 16 bytes in the register file, out of the possi-
ble 256. The lower nibble selects the expanded register file bank and, in the case
of the Z86L88 device, banks 0, F, and D are implemented. A 0h in the lower nibble
allows the normal register file (bank 0) to be addressed, but any other value from
1h to Fh exchanges the lower 16 registers to an expanded register bank. For
example, for the Z86L88 (see Figure 11):
But if:
The counter/timers are mapped into ERF group D. Access is easily performed
using the following:
R253 RP = 00h
R253 RP = 0Dh
LD
LD
LD
LD
LD
LD
LD
LD
An expanded register bank is also referred to as an expanded
register group (see Figure 11).
R0 = Port 0
R1 = Port 1
R2 = Port 2
R3 = Port 3
R0 = CTRL0
R1 = CTRL1
R2 = CTRL2
R3 = Reserved
RP, #0Dh
R0,#xx
1, #xx
R1, 2
RP, #0Dh
RP, #7Dh
71h, 2
R1, 2
; Select ERF D for access to bank D
; (working register group 0)
; load CTRL0
; load CTRL1
; CTRL2→CTRL1
; Select ERF D for access to bank D
; (working register group 0)
; Select expanded register bank D
; working register group 7 of bank 0
; for access.
; CTRL2→register 71h
; CTRL2→register 71h
Low-Voltage IR Microcontroller
Z86L88
20