p89lpc932ba NXP Semiconductors, p89lpc932ba Datasheet - Page 27

• 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
8.18.1 CCU clock (CCUCLK)
8.18.2 CCU clock prescaling
8.18.3 Basic timer operation
8.17 Real-Time clock/system timer
8.18 Capture/Compare Unit (CCU)
The P89LPC932 has a simple Real-Time clock that allows a user to continue running
an accurate timer while the rest of the device is powered-down. The Real-Time clock
can be a wake-up or an interrupt source. The Real-Time clock 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 Real-Time clock and its associated SFRs
to the default state.
This unit features:
The CCU runs on the CCUCLK, which is either PCLK in basic timer mode, or the
output of a PLL. The PLL is designed to use a clock source between 0.5 MHz to
1 MHz that is multiplied by 32 to produce a CCUCLK between 16 MHz and 32 MHz in
PWM mode (asymmetrical or symmetrical). The PLL contains a 4-bit divider to help
divide PCLK into a frequency between 0.5 MHz and 1 MHz.
This CCUCLK can further be divided down by a prescaler. The prescaler is
implemented as a 10-bit free-running counter with programmable reload at overflow.
The Timer is a free-running up/down counter with a direction control bit. If the timer
counting direction is changed while the counter is running, the count sequence will be
reversed. The timer can be written or read at any time.
When a reload occurs, the CCU Timer Overflow Interrupt Flag will be set, and an
interrupt generated if enabled. The 16-bit CCU Timer may also be used as an 8-bit
up/down timer.
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A 16-bit timer with 16-bit reload on overflow.
Selectable clock, with prescaler to divide clock source by any integral number
between 1 and 1024.
4 Compare/PWM outputs with selectable polarity
Symmetrical/Asymmetrical PWM selection
2 Capture inputs with event counter and digital noise rejection filter
7 interrupts with common interrupt vector (one Overflow, 2 Capture, 4 Compare)
Safe 16-bit read/write via shadow registers.
Rev. 04 — 06 January 2004
8-bit microcontroller with accelerated two-clock 80C51 core
© Koninklijke Philips Electronics N.V. 2004. All rights reserved.
P89LPC932
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