ZLP128ICE01ZEM Zilog, ZLP128ICE01ZEM Datasheet - Page 17

• Manufacturer Part Number: ZLP128ICE01ZEM
• Description: EMULATOR CRIMZON Z8 ZLP12840
• Manufacturer: Zilog

Specifications of ZLP128ICE01ZEM

• Interface Type: RS-232, Ethernet, USB
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: 269-3829

I/O Port Pin Functions
PS024410-0108
Note:
Caution:
The ZLP12840 MCU features three 8-bit ports, which are described below.
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•
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Port 0 and 2 internal pull-ups are disabled on any pin or group of pins when programmed
into output mode.
Table 7
also be affected by control registers for other peripheral functions.
The CMOS input buffer for each port 0 or 2 pin is always connected to the pin, even
when the pin is configured as an output. If the pin is configured as an open-drain output
and no external signal is applied, a High output state can cause the CMOS input buffer
to float. This might lead to excessive leakage current of more than 100
this leakage, connect the pin to an external signal with a defined logic level or ensure
its output state is Low, especially during STOP mode.
Port 0, 1, and 2 have both input and output capability. The input logic is always present
no matter whether the port is configured as input or output. When doing a READ in-
struction, the MCU reads the actual value at the input logic but not from the output buff-
er. In addition, the instructions of OR, AND, and XOR have the Read-Modify-Write
sequence. The MCU first reads the port, and then modifies the value and load back to
the port.
Precaution must be taken if the port is configured as open-drain output or if the port is
driving any circuit that makes the voltage different from the desired output logic. For
example, pins P00–P07 are not connected to anything else. If it is configured as open-
drain output with output logic as ONE, it is a floating port and reads back as ZERO. The
following instruction sets P00-P07 all Low.
Port 0 is nibble-programmable as either input or output
Port 2 is bit-programmable as either input or output
Port 3 features four inputs on the lower nibble and four outputs on the upper nibble
summarizes the registers used to control I/O ports. Some port pin functions can
AND P0,#%F0
P R E L I M I N A R Y
Product Specification
I/O Port Pin Functions
µ
A. To prevent
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