Z8PE003 Datasheet, PDF (33/48 Pages) Zilog, Inc. – FEATURE-ENHANCED Z8PLUS 1K ROM ONE-TIME PROGRAMMABLE (OTP) MICROCONTROLLER

ZiLOG
RESET CONDITIONS
After a RESET, the timers are disabled. See Table 8 for timer
control, value, and auto-initialization register status after
RESET.
Z8PE003
Z8Plus OTP Microcontroller
I/O PORTS
The Z8Plus dedicates 14 lines to input and output. These lines
are grouped into two ports known as Port A and Port B. Port
A is an 8-bit port, bit programmable as either inputs or outputs.
Port B can be programmed to provide either standard in-
put/output, or the following special functions: T0 output,
comparator input, SMR input, and external interrupt inputs.
All pins except PB5 include push-pull CMOS outputs. In
addition, the outputs of Port A on a bit-wise basis can be
configured for open-drain operation.The ports operate on
a bit-wise basis. As such, the register values for/at a given
bit position only affect the bit in question.
Each port is defined by a set of four control registers (Figure 26).
PTASFR Bit n
N = 0...7
PTADIR Bit n
N = 0...7
PA0–PA7
PIN
PTAOUT Bit n
N = 0...7
PTAIN Bit n
N = 0...7
Figure 26. Port A Configuration with Open-Drain Capability and Schmitt-Trigger
Directional Control and Special Function
Registers
Each port on the Z8Plus features a dedicated directional con-
trol register that determines (on a bit-wise basis) if a given
port bit operates as input or output.
Each port on the Z8Plus features a special function register
(SFR) that, in conjunction with the directional control reg-
ister, implements (on a bit-by-bit basis) any special func-
tionality that can be defined for each particular port bit.
Table 14. I/O Ports Registers
Register
Port B Special Function
Port B Directional Control
Port B Output Value
Port B Input Value
Port A Special Function
Port A Directional Control
Port A Output Value
Port A Input Value
Address
0D7H
0D6H
0D5H
0D4H
0D3H
0D2H
0D1H
0D0H
Identifier
PTBSFR
PTBDIR
PTBOUT
PTBIN
PTASFR
PTADIR
PTAOUT
PTAIN
Input and Output Value Registers
Each port features an Output Value Register and an input
value register. For port bits configured as an input by means
of the directional control register, the input value register
DS007500-Z8X0399
PRELIMINARY
33