UM10147_2
© NXP B.V. 2008. All rights reserved.
User manual
Rev. 02 — 28 April 2008
55 of 134
NXP Semiconductors
UM10147
P89LPC952/954 User manual
010
0
00
Low frequency crystal
Low frequency crystal
/DIVM
01
10
11
Low frequency crystal
/DIV
1
00
Low frequency crystal
Internal RC oscillator
01
10
11
Internal RC oscillator
011
0
00
High frequency crystal
Internal RC oscillator
/DIVM
01
Medium frequency crystal
10
Low frequency crystal
11
Internal RC oscillator
/DIVM
1
00
High frequency crystal
Internal RC oscillator
01
Medium frequency crystal
10
Low frequency crystal
11
Internal RC oscillator
100
0
00
High frequency crystal
Watchdog oscillator
/DIVM
01
Medium frequency crystal
10
Low frequency crystal
11
Watchdog oscillator /DIVM
1
00
High frequency crystal
Internal RC oscillator
01
Medium frequency crystal
10
Low frequency crystal
11
Internal RC oscillator
101
x
xx
undefined
undefined
110
x
xx
undefined
undefined
111
0
00
External clock input
External clock input
/DIVM
01
10
11
External clock input /DIVM
1
00
External clock input
Internal RC oscillator
01
10
11
Internal RC oscillator
Table 42.
Real-time Clock Control register (RTCCON - address D1h) bit allocation
Bit
7
6
5
4
3
2
1
0
Symbol
RTCF
RTCS1
RTCS0
-
-
-
ERTC
RTCEN
Reset
0
1
1
x
x
x
0
0
Table 41.
Real-time Clock/System Timer clock sources
…continued
FOSC2:0
RCCLK
RTCS1:0
RTC clock source
CPU clock source