P89LPC915 PHILIPS [NXP Semiconductors], P89LPC915 Datasheet - Page 43

• Manufacturer Part Number: P89LPC915
• Description: 8-bit microcontrollers with accelerated two-clock 80C51 core 2 kB 3 V Flash with 8-bit A/D converter
• Manufacturer: PHILIPS [NXP Semiconductors]

Philips Semiconductors
9397 750 14397
Product data
9.16.4 Mode 3
9.16.5 Mode 6
9.16.6 Timer overflow toggle output
9.18.1 Mode 0
9.17 Real-Time clock/system timer
9.18 UART
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.
Timer 0 (and Timer 1 on the P89LPC917) can be configured to automatically toggle
the timer output pin, Tx, whenever a timer overflow occurs. The same device pin that
is used for the count input is also used for the timer toggle output. The port output will
be a logic 1 prior to the first timer overflow when this mode is turned on.
The P89LPC915/916/917 devices have 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 logic 0s, the counter will be reloaded again and the
RTCF flag will be set.
The clock source for this counter can either be the CPU clock (CCLK) or the external
clock input, provided that the external clock input is not being used as the CPU clock.
If the external clock input 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.
The P89LPC915/916/917 has an enhanced UART that is compatible with the
conventional 80C51 UART except that Timer 2 overflow cannot be used as a baud
rate source. The P89LPC915/916/917 does include an independent Baud Rate
Generator. The baud rate can be selected from CCLK (divided by a constant),
Timer 1 overflow, or the independent Baud Rate Generator. In addition to the baud
rate generation, enhancements over the standard 80C51 UART include Framing
Error detection, automatic address recognition, selectable double buffering and
several interrupt options. The UART can be operated in 4 modes: shift register, 8-bit
UART, 9-bit UART, and CCLK/32 or CCLK/16.
Serial data enters and exits through RxD. TxD outputs the shift clock. 8 bits are
transmitted or received, LSB first. The baud rate is fixed at
frequency.
Rev. 04 — 17 December 2004
8-bit microcontrollers with accelerated two-clock 80C51 core
P89LPC915/916/917
© Koninklijke Philips Electronics N.V. 2004. All rights reserved.
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