p89lpc9402 NXP Semiconductors, p89lpc9402 Datasheet - Page 27

• Manufacturer Part Number: p89lpc9402
• Description: 8-bit Microcontroller With Accelerated Two-clock 80c51 Core 8 Kb 3 V Byte-erasable ?ash With 32 Segment 4 Lcd Driver
• Manufacturer: NXP Semiconductors

NXP Semiconductors
P89LPC9402_1
Product data sheet
7.18.2 Mode 1
7.18.3 Mode 2
7.18.4 Mode 3
7.18.5 Mode 6
7.18.6 Timer overflow toggle output
7.20.1 Mode 0
7.19 RTC/system timer
7.20 UART
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.
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.
The P89LPC9402 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 logic 0s, 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. Only power-on reset and watchdog reset will
reset the RTC and its associated SFRs to the default state.
The 16-bit loadable counter portion of the RTC is readable by reading the RTCDATL and
RTCDATH registers.
The P89LPC9402 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
P89LPC9402 does include an independent Baud Rate Generator. The baud rate can be
selected from the oscillator (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
four modes: shift register, 8-bit UART, 9-bit UART, and CPU clock/32 or CPU clock/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. 01 — 22 April 2009
8-bit microcontroller with accelerated two-clock 80C51 core
1
16
P89LPC9402
of the CPU clock
© NXP B.V. 2009. All rights reserved.
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