P89LPC952 Datasheet, PDF (31/66 Pages) NXP Semiconductors – 8-bit microcontroller with accelerated two-clock 80C51 core 8 kB 3 V byte-erasable flash with 10-bit ADC

Philips Semiconductors
P89LPC952
8-bit microcontroller with 10-bit ADC
In the ‘Counter’ function, the register is incremented in response to a 1-to-0 transition at its
corresponding external input pin, T0 or T1. In this function, the external input is sampled
once during every machine cycle.
Timer 0 and Timer 1 have five operating modes (Modes 0, 1, 2, 3 and 6). Modes 0, 1, 2
and 6 are the same for both Timers/Counters. Mode 3 is different.
7.17.1 Mode 0
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.
7.17.2 Mode 1
Mode 1 is the same as Mode 0, except that all 16 bits of the timer register are used.
7.17.3 Mode 2
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.
7.17.4 Mode 3
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.
7.17.5 Mode 6
In this mode, the corresponding timer can be changed to a PWM with a full period of
256 timer clocks.
7.17.6 Timer overflow toggle output
Timers 0 and 1 can be configured to automatically toggle a port output whenever a timer
overflow occurs. The same device pins that are used for the T0 and T1 count inputs are
also used for the timer toggle outputs. The port outputs will be a logic 1 prior to the first
timer overflow when this mode is turned on.
7.18 RTC/system timer
The P89LPC952 has a simple RTC that allows a user to continue running an accurate
timer while the rest of the device is powered down. The RTC can be a wake-up or an
interrupt source. The RTC is a 23-bit down-counter comprised of a 7-bit prescaler and a
16-bit loadable down-counter. When it reaches all ‘0’s, the counter will be reloaded again
and the RTCF flag will be set. The clock source for this counter can be either the CPU
clock (CCLK) or the XTAL oscillator, provided that the XTAL oscillator is not being used as
the CPU clock. If the XTAL oscillator is used as the CPU clock, then the RTC will use
CCLK as its clock source. Only power-on reset will reset the RTC and its associated SFRs
to the default state.
9397 750 14716
Preliminary data sheet
Rev. 01— 16 September 2005
© Koninklijke Philips Electronics N.V. 2005. All rights reserved.
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