ZLF645 MAXIM [Maxim Integrated Products], ZLF645 Datasheet - Page 26

• Manufacturer Part Number: ZLF645
• Description: Flash MCUs with Learning Amplification
• Manufacturer: MAXIM [Maxim Integrated Products]

I/O Port Pin Functions
PS026408-1208
RESET (Input, Active Low)
Note:
Caution:
The ZLF645 MCU features up to five 8-bit ports which are described below:
1. Port 0 is nibble-programmable as either input or output.
2. Port 1 is byte-programmable as either input or output.
3. Port 2 is bit-programmable as either input or output.
4. Port 3 features four inputs on the lower nibble and four outputs on the upper nibble.
5. Port 4 is bit-programmable as either input or output.
Port 0, Port 1, Port 2, and Port 4 internal pull-ups are disabled on any pin or group of pins
when programmed into output mode.
Reset initializes the MCU and is accomplished either through Power-On Reset (POR),
Watchdog Timer
external reset pin in the case of 48-pin packaged products.
AND P0,#%F0
The CMOS input buffer for each Port 0, Port 1, Port 2, or Port 4 pin are 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 may lead to excessive leakage current of more than
100
level or ensure that its output state is Low, especially during STOP mode.
Port 0, Port 1, Port 2, and Port 4 have both input and output capability. The input logic
is always present no matter whether the port is configured as input or output. When
executing a READ instruction, the MCU reads the actual value at the input logic but not
from the output buffer. In addition, the instructions of OR, AND, and XOR have the Read-
Modify-Write sequence. The MCU first reads the port, then modifies the value, and loads
back to the port.
Precaution must be taken, if the port is configured as an open-drain output or if the port
is driving any circuit that makes the voltage different from the appropriate output logic.
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:

A. To prevent this leakage, connect the pin to an external signal with a defined logic
(WDT), Stop Mode Recovery, Low-Voltage detection, or through the
Product Specification
I/O Port Pin Functions
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