p89lpc932ba NXP Semiconductors, p89lpc932ba Datasheet - Page 18

• Manufacturer Part Number: p89lpc932ba
• Description: P89lpc932 8-bit Microcontroller With Accelerated Two-clock 80c51 Core 8 Kb Flash With 512-byte Data Eeprom And 768-byte Ram
• Manufacturer: NXP Semiconductors

Philips Semiconductors
9397 750 12379
Product data
8.2.6 Clock output
8.3 On-chip RC oscillator option
8.4 Watchdog oscillator option
8.5 External clock input option
The P89LPC932 supports a user-selectable clock output function on the
XTAL2/CLKOUT pin when crystal oscillator is not being used. This condition occurs if
another clock source has been selected (on-chip RC oscillator, watchdog oscillator,
external clock input on X1) and if the Real-Time clock is not using the crystal
oscillator as its clock source. This allows external devices to synchronize to the
P89LPC932. This output is enabled by the ENCLK bit in the TRIM register.
The frequency of this clock output is
needed in Idle mode, it may be turned off prior to entering Idle, saving additional
power.
The P89LPC932 has a 6-bit TRIM register that can be used to tune the frequency of
the RC oscillator. During reset, the TRIM value is initialized to a factory
pre-programmed value to adjust the oscillator frequency to 7.373 MHz, 2.5 %.
End-user applications can write to the TRIM register to adjust the on-chip RC
oscillator to other frequencies.
The watchdog has a separate oscillator which has a frequency of 400 kHz. This
oscillator can be used to save power when a high clock frequency is not needed.
In this configuration, the processor clock is derived from an external source driving
the XTAL1/P3.1 pin. The rate may be from 0 Hz up to 12 MHz. The XTAL2/P3.0 pin
may be used as a standard port pin or a clock output.
Fig 6. Block diagram of oscillator control.
XTAL1
XTAL2
(400 kHz +20% -30%)
(7.3728 MHz ±2.5%)
OSCILLATOR
OSCILLATOR
WATCHDOG
RC
TIMER 0 and
Rev. 04 — 06 January 2004
TIMER 1
High freq.
Med. freq.
Low freq.
RCCLK
8-bit microcontroller with accelerated two-clock 80C51 core
I
2
C
OSCCLK
1
2
PCLK
that of the CCLK. If the clock output is not
DIVM
SPI
CCLK
PCLK
© Koninklijke Philips Electronics N.V. 2004. All rights reserved.
2
UART
P89LPC932
32 PLL
WDT
RTC
CPU
CCU
002aaa515
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