Z89175 Datasheet, PDF (29/68 Pages) Zilog, Inc. – Voice Processing Controllers

Zilog
Z89175/Z89176
Voice Processing Controllers
Port 5 (P53-P50). Port 5 is a 4-bit, bidirectional, CMOS Port 5 is a bit programmable general-purpose I/O port. The
compatible I/O port (Figure 16). These four I/O lines are control registers for Port 5 are mapped into the expanded
configured under software control independently as inputs register file (Bank F) of the Z8.
or outputs. Port 5 is always available for I/O operation. The
2
input buffers are Schmitt-triggered. Bits programmed as ^{Auto Latch. The Auto Latch on Port 5 puts valid CMOS}
outputs can be globally programmed as either push-pull or ^{levels on all CMOS inputs which are not externally driven.}
open-drain.
Whether this level is 0 or 1 cannot be determined. A valid
CMOS level, rather than a floating node, reduces exces-
sive supply current flow in the input buffer.
Z89175/176
MCU
Port 5
(I/O)
Open-Drain
OEN
Out
1.5
2.3V Hysteresis
In
R = 500 KΩ
Figure 16. Port 5 Configuration
Pad
Auto Latch
DS97TAD0100
PRELIMINARY
29