Real-Time Clock Interrupt/Wake Up; Reset Sources Affecting The Real-Time Clock; Real-Time Clock/System Timer Clock Sources - Philips P89LPC920 User Manual

Philips Semiconductors
REAL-TIME CLOCK/SYSTEM TIMER

Real-time Clock interrupt/wake up

If ERTC (RTCCON.1), EWDRT (IEN1.0.6) and EA (IEN0.7) are set to '1', RTCF can be used as an interrupt source. This interrupt
vector is shared with the watchdog timer. It can also be a source to wake up the device.

Reset sources affecting the Real-time Clock

Only power-on reset will reset the Real-time Clock and its associated SFRs to their default state
Table 8-1: Real-time Clock/System Timer clock sources
RTCS1 RTCS0
(RTCCON.6) (RTCCON.5)
x x
x x
x x
0 0
0 1
1 0
1 1
0 0
0 1
1 0
1 1
x x
x x
x x
2003 Dec 8
FOSC2 FOSC1
(UCFG1.2) (UCFG1.1) (UCFG1.0)
0 0
0 0
0 1
0 1
1 0
1 0
1 1
1 1
FOSC0
RTC clock source
0 CCLK
1 CCLK
0 CCLK
High frequency crystal
Medium frequency crystal
1
Low frequency crystal
CCLK
High frequency crystal
Medium frequency crystal
0
Low frequency crystal
CCLK
1 undefined
0 undefined
1 CCLK
48
User's Manual - Preliminary -
P89LPC920/921/922
CPU clock source
High frequency crystal
Medium frequency crystal
Low frequency crystal
Internal RC oscillator
Watchdog oscillator
undefined
undefined
External clock input