UM10147_2
© NXP B.V. 2008. All rights reserved.
User manual
Rev. 02 — 28 April 2008
123 of 134
NXP Semiconductors
UM10147
P89LPC952/954 User manual
17.18 User security bytes
This device has three security bits associated with each of its eight/ sixteen sectors, as
shown in
4
WDSE
Watchdog Safety Enable bit. Refer to
Table 90 “Watchdog timer configuration”
for details.
5
BOE
Brownout Detect Enable (see
Section 6.1 “Brownout detection”
6
RPE
Reset pin enable. In combination with RPE1 (UCFG2.0) , determines the mode of the reset pin, see
. NOTE: During a power-up sequence, the RPE and RPE1 selection is overridden and
this pin will always functions as a reset input. After power-up the pin will function as defined by the RPE and
RPE1 bits. Only a power-up reset will temporarily override the selection defined by RPE and RPE1 bits.
Other sources of reset will not override the RPE and RPE1 bits.
The following reset pin modes are selected by and RPE1 (UCFG2.00 and RPE (UCFG1.6) bits:
00 —
Normal input pin
01 —
Reset input pin
10 —
Bidirectional open drain reset
11 —
Reset output only
7
WDTE
Watchdog timer reset enable. When set = 1, enables the watchdog timer reset. When cleared = 0, disables
the watchdog timer reset. The timer may still be used to generate an interrupt. Refer to
for details.
Table 106. Flash User Configuration Byte 1 (UCFG1) bit description
…continued
Bit Symbol
Description
Table 107. Oscillator type selection
FOSC[2:0] Oscillator configuration
111
External clock input on XTAL1.
100
Watchdog Oscillator, 400 kHz (+20/
−
30 % tolerance).
011
Internal RC oscillator, 7.373 MHz ± 2.5 %.
010
Low frequency crystal, 20 kHz to 100 kHz.
001
Medium frequency crystal or resonator, 100 kHz to 4 MHz.
000
High frequency crystal or resonator, 4 MHz to 18 MHz.
Table 108. Flash User Configuration Byte 2 (UCFG2) bit allocation
Bit
7
6
5
4
3
2
1
0
Symbol
-
-
DBG
-
-
-
-
RPE1
Unprogrammed
value
x
x
0
x
x
x
x
x
Table 109. Flash User Configuration Byte 2 (UCFG2) bit description
Bit Symbol
Description
0
RPE1
Reset pin enable 1. In combination with RPE (UCFG1.6) , determines the mode of the reset pin, see
. NOTE: During a power-up sequence, the RPE and RPE1 selection is
overridden and this pin will always functions as a reset input. After power-up the pin will function as defined
by the RPE and RPE1 bits. Only a power-up reset will temporarily override the selection defined by RPE
and RPE1 bits. Other sources of reset will not override the RPE and RPE1 bits.
1:4 -
Not used.
5
DBG
When set = 1, enables the use of the debugger on the TCLK, TDI, and TRIG pins.
6:7 -
Not used.