p89lpc9402 NXP Semiconductors, p89lpc9402 Datasheet - Page 26

• 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
7.17.1 Reset vector
7.18.1 Mode 0
7.18 Timers/counters 0 and 1
Note: During a power cycle, V
to ensure a power-on reset (see
Reset can be triggered from the following sources:
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 P89LPC9402 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
P89LPC9402 User manual ). Otherwise, instructions will be fetched from address 0000H.
The P89LPC9402 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.
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External reset pin (during power-up or if user configured via UCFG1)
Power-on detect
Brownout detect
Watchdog timer
Software reset
UART break character detect reset
During a power-on reset, both POF and BOF are set but the other flag bits are
cleared.
A Watchdog reset is similar to 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.
Rev. 01 — 22 April 2009
8-bit microcontroller with accelerated two-clock 80C51 core
DD
Table 12 “Static electrical
must fall below V
POR
before power is reapplied, in order
characteristics”).
P89LPC9402
© NXP B.V. 2009. All rights reserved.
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