TMP91C824
91C824-20
2008-02-20
Example 2: Setting the clock
Changing from low frequency (fs) to high frequency (fc).
SYSCR0 EQU 00E0H
SYSCR1 EQU 00E1H
SYSCR2 EQU 00E2H
LD
(SYSCR2),
X
−
10
−
−
−
−
B ; Sets warm-up time to 214/fc.
SET
7, (SYSCR0)
; Enables high-frequency oscillation.
SET
2, (SYSCR0)
; Clears and starts warm-up timer.
WUP: BIT 2,
(SYSCR0)
;
JR
NZ,
WUP
;
RES
3, (SYSCR1)
; Changes fSYS from fs to fc.
RES
6, (SYSCR0)
; Disables low-frequency oscillation.
X: Don’t care,
−
: No change
Detects stopping of warm-up timer.
Counts up by f
OSCH
<XEN>
X1, X2 pins
XT1, XT2 pins
<XTEN>
Warm-up timer
End of warm-up timer
<SYSCK>
System clock f
SYS
Enables
high frequency
Clears and starts
warm-up timer
End of warm-up
timer
Chages f
SYS
from fs to fc
Disables
low frequency
fc
Counts up by f
SYS
fs