S3F84B8_UM_REV 1.00
9 I/O PORTS
9-1
9
I/O PORTS
9.1 OVERVIEW OF I/O PORTS
The S3F84B8 microcontroller has three bit-programmable I/O ports (P0, P1, and P2) and 17 I/O pins. Each port
can be easily configured to meet the application design requirements. The CPU accesses ports by directly writing
or reading the port registers. No special I/O instructions are required.
provides a general overview of the S3F84B8 I/O port functions.
Table 9-1 S3F84B8 Port Configuration Overview
Port
Configuration Options
0
I/O port with bit-programmable pins. Configurable to input or push-pull output mode. Pull-up
resistors can be assigned by the software. Pins can also be assigned individually as alternative
function pins.
1
I/O port with bit-programmable pins. Configurable to input or push-pull output mode. Pull-up
resistors can be assigned by the software. Pins can also be assigned individually as alternative
function pins.
2
I/O port with bit-programmable pins. Configurable to input mode or push-pull output mode. Pins can
also be assigned individually as alternative function pins.
For better Electrical Fast transients Test (EFT) performance, when P10, P11, P12, P24, and P25 (with alternative
function as comparator input) are configured as input pins, it is recommended to add 102pF capacitor externally.
9.1.1 PORT DATA REGISTERS
provides an overview of the register locations of all three S3F84B8 I/O port data registers. Data
registers for ports 0, 1, and 2 have the general format, as shown in
.
Table 9-2 Port Data Register Summary
Register Name
Mnemonic
Decimal
Hex
Location
R/W
Port 0 data register
P0
224
E0H
Set1, Bank0
R/W
Port 1 data register
P1
225
E1H
Set1, Bank0
R/W
Port 2 data register
P2
226
E2H
Set1, Bank0
R/W
