P89LPC913 PHILIPS [NXP Semiconductors], P89LPC913 Datasheet - Page 32

• Manufacturer Part Number: P89LPC913
• Description: 8-bit microcontrollers with two-clock 80C51 core 1 kB 3 V Flash with 128-byte RAM
• Manufacturer: PHILIPS [NXP Semiconductors]

Philips Semiconductors
9397 750 14468
Product data
9.11.1 Port configurations
9.11.2 Quasi-bidirectional output configuration
Table 10:
[1]
The P89LPC914 has 3 I/O ports: Port 0, Port 1, and Port 2. The exact number of I/O
pins available depends on the reset option chosen, as shown in
Table 11:
[1]
Except as listed below, every I/O pin on the P89LPC912/913/914 may be configured
by software to one of four types on a bit-by-bit basis. These are: quasi-bidirectional
(standard 80C51 port outputs), push-pull, open drain, and input-only. Two
configuration registers for each port select the output type for each port pin.
P1.5/RST can only be an input and cannot be configured.
P1.2/T0 may only be configured to be either input-only or open drain (P89LPC912,
P89LPC914).
Quasi-bidirectional output type can be used as both an input and output without the
need to reconfigure the port. This is possible because when the port outputs a logic
HIGH, it is weakly driven, allowing an external device to pull the pin LOW. When the
pin is driven LOW, it is driven strongly and able to sink a fairly large current. These
features are somewhat similar to an open-drain output except that there are three
pull-up transistors in the quasi-bidirectional output that serve different purposes.
The P89LPC912/913/914 is a 3 V device, but the pins are 5 V-tolerant. In
quasi-bidirectional mode, if a user applies 5 V on the pin, there will be a current
flowing from the pin to V
5 V in quasi-bidirectional mode is discouraged.
Clock source
On-chip oscillator or watchdog
oscillator
External clock input
Low/medium/high speed oscillator
(external crystal or resonator)
Reset option
No external reset (except during power-up)
External RST pin supported
Required for operation above 12 MHz.
Required for external clock frequency above 12 MHz.
Number of I/O pins available (P89LPC912, P89LPC913)
Number of I/O pins available (P89LPC914)
Rev. 03 — 17 December 2004
DD
[1]
, causing extra power consumption. Therefore, applying
8-bit microcontrollers with two-clock 80C51 core
Reset option
No external reset (except during
power-up)
External RST pin supported
No external reset (except during
power-up)
External RST pin supported
No external reset (except during
power-up)
External RST pin supported
P89LPC912/913/914
© Koninklijke Philips Electronics N.V. 2004. All rights reserved.
Number of I/O pins
(14-pin package)
12
11
[1]
Table
11.
Number of
I/O pins
(14-pin
package)
12
11
11
10
10
9
32 of 63