Z86L79 Datasheet, PDF (14/58 Pages) Zilog, Inc. – Low-Voltage Microcontroller

Z86L79/80
Low-Voltage Microcontroller
PIN FUNCTIONS (Continued)
Port 2 (P27-P20). Port 2 is an 8-bit, bidirectional, CMOS
compatible I/O port. These eight I/O lines can be indepen-
dently configured under software control as inputs or out-
puts. Port 2 is always available for I/O operation. A mask
option is available to connect eight 200 kOhms (±50%)
pull-up resistors on this port. Bits programmed as outputs
are globally programmed as either push-pull or open-
drain. Port 2 may be placed under handshake control. In
this configuration, Port 3 lines, P31 and P36 are used as
the handshake controls lines /DAV2 and RDY2. The hand-
Zilog
shake signal assignment for Port 3, lines P31 and P36 is
dictated by the direction (input or output) assigned to Bit 7,
Port 2 (Figure 6). The CCP wakes up with the eight bits of
Port 2 configured as inputs with open-drain outputs.
Port 2 also has an 8-bit input NOR and an NAND gates
which can be used to wake up the part from STOP mode
(Figure 38). P20 can be programmed to access the edge
selection circuitry (Figure 10).
3-14
Z86L7X
MCU
Open-Drain
OEN
Port 2 (I/O)
Optional
Handshake Controls
/DAV2 and RDY2
(P31 and P36)
VCC
200 kΩ
Mask
Option
PAD
Out
In
Figure 10. Port 2 Configuration
PRELIMINARY
DS97LVO0601