AT89LP216-20PI ATMEL [ATMEL Corporation], AT89LP216-20PI Datasheet - Page 22

• Manufacturer Part Number: AT89LP216-20PI
• Description: Microcontroller with 2K Bytes Flash
• Manufacturer: ATMEL [ATMEL Corporation]

13. I/O Ports
13.1
22
Port Configuration
AT89LP216 [Preliminary]
The AT89LP216 can be configured for between 9 and 12 I/O pins. The exact number of I/O pins
available depends on the clock and reset options as shown in
tolerant, that is they can be pulled up or driven to 5.5V even when operating at a lower V
as 3V.
Table 13-1.
All port pins on the AT89LP216 may be configured to one of four modes: quasi-bidirectional
(standard 8051 port outputs), push-pull output, open-drain output, or input-only. Port modes may
be assigned in software on a pin-by-pin basis as shown in
Fuse determines the default state of the port pins. When the fuse is enabled, all port pins default
to input-only mode after reset. When the fuse is disabled, all port pins, with the exception of P1.0
and P1.1, default to quasi-bidirectional mode after reset and are weakly pulled high. Each port
pin also has a Schmitt-triggered input for improved input noise rejection. During Power-down all
the Schmitt-triggered inputs are disabled with the exception of P1.3, P3.2 and P3.3, which may
be used to wake up the device. Therefore, P1.3, P3.2 and P3.3 should not be left floating during
Power-down
.
Table 13-2.
Clock Source
External Crystal or Resonator
External Clock
Internal RC Oscillator
PxM0.y
0
0
1
1
I/O Pin Configurations
Configuration Modes for Port x, Bit y
PxM1.y
0
1
0
1
External RST Pin
No external reset
External RST Pin
No external reset
External RST Pin
No external reset
Reset Option
Port Mode
Quasi-bidirectional
Push-pull Output
Input Only (High Impedance)
Open-Drain Output
Table
Table
13-2. The Tristate-Port User
13-1. All port pins are 5V
Number of I/O Pins
3621A–MICRO–6/06
11
12
12
13
13
14
CC
such