TMP91C824
91C824-19
Example 1-Setting the clock
Changing from high frequency (fc) to low frequency (fs).
SYSCR0
EQU
00E0H
SYSCR1
EQU
00E1H
SYSCR2
EQU
00E2H
LD
(SYSCR2), X
−
11
−
−
X
−
B
;
Sets warm-up time to 2
16
/fs.
SET
6, (SYSCR0)
;
Enables low-frequency oscillation.
SET
2, (SYSCR0)
;
Clears and starts warm-up timer.
WUP:
BIT
2, (SYSCR0)
;
JR
NZ, WUP
;
Detects stopping of warm-up timer.
SET
3, (SYSCR1)
;
Changes f
SYS
from fc to fs.
RES
7, (SYSCR0)
;
Disables high -frequency oscillation.
(note) “ x” means don’t care
“-“ means no change
fc
fs
Counts up by fs
<XEN>
X1, X2 pins
XT1, XT2 pins
<XTEN>
Warming Up Timer
End of Warming Up Timer
<SYSCK>
System Clock f
SYS
Enables
low Frequency
Clears and starts
warming-up timer
End of warming up timer
Chages fsys
from fc to fs
Disabiles
high-frequency
Counts up by f
SYS