P89LPC913 datasheet(32/63 Pages) PHILIPS

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Philips Semiconductors

P89LPC912/913/914

8-bit microcontrollers with two-clock 80C51 core

Product data

Rev. 03 — 17 December 2004

32 of 63

9397 750 14468

[1]

Required for operation above 12 MHz.

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]

Required for external clock frequency above 12 MHz.

9.11.1

Port conﬁgurations

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).

9.11.2

Quasi-bidirectional output conﬁguration

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 VDD, causing extra power consumption. Therefore, applying

5 V in quasi-bidirectional mode is discouraged.

Table 10:

Number of I/O pins available (P89LPC912, P89LPC913)

Clock source

Reset option

Number of

I/O pins

(14-pin

package)

On-chip oscillator or watchdog

oscillator

No external reset (except during

power-up)

External RST pin supported

External clock input

No external reset (except during

power-up)

External RST pin supported

Low/medium/high speed oscillator

(external crystal or resonator)

No external reset (except during

power-up)

External RST pin supported[1]

Table 11:

Number of I/O pins available (P89LPC914)

Reset option

Number of I/O pins

(14-pin package)

No external reset (except during power-up)

External RST pin supported[1]

P89LPC913 Datasheet(PDF) 32 Page - NXP Semiconductors

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