Z8 Microcontrollers
ZiLOG I/O Ports
UM001601-0803 5-3
5.2.1 General I/O Mode
Port 0 can be an 8-bit, bidirectional, CMOS or TTL compatible
I/O port. These eight I/O lines can be configured under software
control as a nibble I/O port (P03-P00 input/output and P07-P04
input/output), or as an address port for interfacing external mem
-
ory. The input buffers can be Schmitt-triggered, level shifted, or
a single-trip point buffer and can be nibble programmed. Either
nibble output can be globally programmed as push-pull or open-
drain. Low EMI output buffers in some cases can be globally
programmed by the software, as an OTP program option, or as a
ROM mask option. In some, the Z8 has Auto Latches hardwired
to the inputs. Please refer to specific product specifications for
exact input/output buffer type features that are available (Figures
5-3 and 5-4).
Figure 5-3. Port 0 Configuration with Open-Drain Capability, Auto Latch, and Schmitt-Trigger
OEN
Port 1
(I/O or AD15 - AD08)
Handshake Controls
/DAV0 and RDY0
4
Z8
(P32 and P35)
PIN
OUT
IN
2.3V Hysteresis
OPEN-DRAIN
1.5
R ≈ 500 KΩ
Auto Latch
4
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