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Philips Semiconductors
User’s Manual - Preliminary -
P89LPC901/902/903
FLASH PROGRAM MEMORY
2003 Dec 8 100
Figure 14-7: Flash User Configuration Byte 1 (UCFG1)
UCFG1
Address: xxxxh
Default: 63h
BIT SYMBOL FUNCTION
UCFG1.7 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 Table 12-1 for details.
UCFG1.6 RPE Reset pin enable. When set =1, enables the reset function of pin P1.5. When cleared, P1.5
may be used as an input pin. NOTE: During a power-up sequence, the RPE selection is
overriden and this pin will always functions as a reset input. After power-up the pin will
function as defined by the RPE bit. Only a power-up reset will temporarily override the
selection defined by RPE bit. Other sources of reset will not override the RPE bit.
UCFG1.5 BOE Brownout Detect Enable (see section "Brownout Detection").
UCFG1.4 WDSE Watchdog Safety Enable bit. Refer to Table for details.
UCFG1.3 - Reserved (should remain unprogrammed at zero).
UCFG1.2-0 FOSC2-FSOC0 CPU oscillator type select. See section "Low Power Select (P89LPC901)" for additional
information. Combinations other than those shown below should not be used. They are
reserved for future use.When FOSC2:0 select either the internal RC or Watchdog
oscillators, the crystal oscillator configuration is controlled by RTCCON. See Table and
Table . Note: External clock input and crystal options are available on the
P89LPC901.
FOSC2-FOSC0
Oscillator Configuration
1 1 1 External clock input on XTAL1.
1 0 0 Watchdog Oscillator, 400KHz (+20/ -30% tolerance).
0 1 1 Internal RC oscillator, 7.373MHz ±2.5%.
0 1 0 Low frequency crystal, 20 kHz to 100 kHz.
0 0 1 Medium frequency crystal or resonator, 100 kHz to 4 MHz.
0 0 0 High frequency crystal or resonator, 4 MHz to 12 MHz.
Factory default value for UCFG1 is set for watchdog reset disabled, reset pin enabled, brownout detect enabled, and using
the internal RC oscillator
76543210
WDTE RPE BOE WDSE - FOSC2 FOSC1 FOSC0