p89lpc9401 NXP Semiconductors, p89lpc9401 Datasheet - Page 25

• Manufacturer Part Number: p89lpc9401
• Description: 8-bit Microcontroller With Accelerated Two-clock 80c51 Core 8 Kb 3 V Byte-erasable Flash With 32 Segment X 4 Lcd Driver
• Manufacturer: NXP Semiconductors

Philips Semiconductors
P89LPC9401_1
Preliminary data sheet
7.16.1 Reset vector
7.17.1 Mode 0
7.17.2 Mode 1
7.17.3 Mode 2
7.17.4 Mode 3
7.17 Timers/counters 0 and 1
For every reset source, there is a flag in the Reset Register, RSTSRC. The user can read
this register to determine the most recent reset source. These flag bits can be cleared in
software by writing a logic 0 to the corresponding bit. More than one flag bit may be set:
Following reset, the P89LPC9401 will fetch instructions from either address 0000H or the
Boot address. The Boot address is formed by using the Boot Vector as the high byte of the
address and the low byte of the address = 00H.
The Boot address will be used if a UART break reset occurs, or the non-volatile Boot
Status bit (BOOTSTAT.0) = 1, or the device is forced into ISP mode during power-on (see
P89LPC9401 User manual ). Otherwise, instructions will be fetched from address 0000H.
The P89LPC9401 has two general purpose counter/timers which are upward compatible
with the standard 80C51 Timer 0 and Timer 1. Both can be configured to operate either as
timers or event counter. An option to automatically toggle the T0 and/or T1 pins upon timer
overflow has been added.
In the ‘Timer’ function, the register is incremented every machine cycle.
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.
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.
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.
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During a power-on reset, both POF and BOF are set but the other flag bits are
cleared.
For any other reset, previously set flag bits that have not been cleared will remain set.
8-bit two-clock 80C51 microcontroller with 32 segment
Rev. 01 — 5 September 2005
© Koninklijke Philips Electronics N.V. 2005. All rights reserved.
P89LPC9401
4 LCD driver
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