P89LPC901 PHILIPS [NXP Semiconductors], P89LPC901 Datasheet - Page 34

• Manufacturer Part Number: P89LPC901
• 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 12293
Product data
8.16.1 Mode 0
8.16.2 Mode 1
8.16.3 Mode 2
8.16.4 Mode 3
8.16.5 Mode 6 (P89LPC901)
8.16 Timers/counters 0 and 1
Reset can be triggered from the following sources:
For every reset source, there is a flag in the Reset Register, RSTSRC. The user can
read this register to determine the most recent reset source. These flag bits can be
cleared in software by writing a ‘0’ to the corresponding bit. More than one flag bit
may be set:
The P89LPC901/902/903 has two general purpose timers which are similar to the
standard 80C51 Timer 0 and Timer 1. These timers have four operating modes
(modes 0, 1, 2, and 3). Modes 0, 1, and 2 are the same for both Timers. Mode 3 is
different.
Putting either Timer into Mode 0 makes it look like an 8048 Timer, which is an 8-bit
Counter with a divide-by-32 prescaler. In this mode, the Timer register is configured
as a 13-bit register. Mode 0 operation is the same for Timer 0 and Timer 1.
Mode 1 is the same as Mode 0, except that all 16 bits of the timer register are used.
Mode 2 configures the Timer register as an 8-bit Counter with automatic reload.
Mode 2 operation is the same for Timer 0 and Timer 1.
When Timer 1 is in Mode 3 it is stopped. Timer 0 in Mode 3 forms two separate 8-bit
counters and is provided for applications that require an extra 8-bit timer. When
Timer 1 is in Mode 3 it can still be used by the serial port as a baud rate generator.
In this mode, the corresponding timer can be changed to a PWM with a full period of
256 timer clocks.
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External reset pin (during power-up or if user configured via UCFG1)
Power-on detect
Brownout detect
Watchdog Timer
Software reset
UART break character detect reset (P80LPC903).
During a power-on reset, both POF and BOF are set but the other flag bits are
cleared.
For any other reset, previously set flag bits that have not been cleared will remain
set.
Rev. 04 — 21 November 2003
8-bit microcontrollers with two-clock 80C51 core
P89LPC901/902/903
© Koninklijke Philips Electronics N.V. 2003. All rights reserved.
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