ZiLOG Z8 Series User Manual

Z8
®
CPU
User Manual
UM001604-0108 Address Space
14
Because enabling an ERF Bank (C or F) only changes register addresses 00h to 0Fh, the
working register pointer can be used to access either the selected ERF Bank (Bank C or F,
Working Register Group 0) or the
Z8
®
Standard Register File (ERF Bank 0, Working Reg-
ister Groups 1 through F).
When an ERF Bank other than Bank 0 is enabled, the first 16 bytes of
the Z8 Standard
Register File (I/O ports 0 to 3, Groups 4 to F) are no longer accessible (the selected ERF
Bank, Registers
00h to 0Fh are accessed instead). It is important to re-initialize the Regis-
ter Pointer to enable ERF Bank 0 when these registers are required for use.
The SPI register is mapped into ERF Bank C. Access is easily done using the example in
Table 6.
If R253 RP = FFh
;ERF Bank F, Working Reg.
Group F.
00h = PCON
R0 = SI0 01h = Reserved
R1 = TMR 02h = Reserved
...
R2 = T1 0Bh = SMR
...
R15 = SPL 0Fh = WDTMR
Table 6. ERF Bank C Access Example
LD RP, #0Ch ;Select ERF Bank C working
;register group 0 for access.
LD R2,#xx ;access SCON
LD R1, #xx ;access RXBUF
LD RP, #00h ;Select ERF Bank 0 so I/O ports
;are again accessible.
Table 5. Register Pointer Access Example (Continued)

ZiLOG Z8 Series Specifications

General

Brand	ZiLOG
Model	Z8 Series
Category	Microcontrollers
Language	English

Summary

Address Space

Z8 CPU Standard Register File

Details the standard register file structure, including I/O, general-purpose, and control registers.

Z8 Expanded Register File (ERF)

Reset

Reset Pin, Internal POR Operation

Explains the function of the RESET pin and internal Power-On Reset for chip initialization.

Watchdog Timer

Watchdog Timer

Describes the retriggerable one-shot timer that resets the CPU if it reaches its terminal count.

Counters and Timers

TIN Modes

Interrupts

Interrupt Sources

Lists interrupt types, sources, and vectors available in the Z8 family processors.

Interrupt Initialization

Power-Down Modes

Halt Mode Operation

Explains HALT mode, suspending execution while keeping the oscillator active.

Stop Mode Operation

Details STOP mode for lowest standby current by turning off internal clocks.

Serial Input/Output

UART Introduction

SPI Operation

Details SPI usage in master and slave modes, including data transfer and chip select.

External Interface

Introduction

External Addressing Configuration

Instruction Set

Processor Flags

Condition Codes

Instruction Description

Provides detailed descriptions of Z8 instructions, including syntax, operation, and flags.