Z86318 Datasheet, PDF (12/26 Pages) Zilog, Inc. – Z8 MCU 8-BIT MICROCONTROLLER

Z86318
Z8^® MCU 8-Bit Microcontroller
PIN FUNCTIONS (Continued)
Port 2 (P27-P20). Port 2 is an 8-bit, bit-programmable, bi-
directional, CMOS-compatible I/O port. P23-P20 can be
configured under software control to be input or output, in-
dependently. Note: Bits D3 and D4 of POIM register must
be set to 0. Bits programmed as outputs may be globally
programmed as either push-pull or open-drain via bit D0,
P3M register. P20 and P21 can be configured with a ROM
mask option for 10 Kohm pull-up/pull-down, or none. P22
and P23 can be configured with a ROM mask option for
100 Kohm pull-up/pull-down, or none (Figure 8). No cur-
rent is drawn if pull-up/pull-down is disabled. Note: P23-20
are configured for pull-up/pull-down/none globally.
P24-P27 can be configured as a voltage divider. The volt-
age divider consists of an internal 25K pull-up resistor (Fig-
ure 9), and a 7.5K pull-down resistor. The zero trip-point in-
put levels on P24-P27 are adjusted for connection to the
emitters of opto-transistors and switch at a voltage level of
0.4 VDD. All four of the voltage dividers are globally con-
figured as enabled or disabled.
/Open-Drain
/OEN
Pull-Up
Enable
Out
In
Pull-Down
Enable
Note: P20, P21: 10K Pull-Up/Down or none.
P22, P23: 100K Pull-Up/Down or none.
P23-20 are globally selected for Pull-Up/Down or none.
Figure 8. Port 2 P20-P23 Configuration
Pad
12
PRELIMINARY