TMP91C824
91C824-19
2008-02-20
Example 1: Setting the clock
Changing from high frequency (fc) to low frequency (fs).
SYSCR0 EQU 00E0H
SYSCR1 EQU 00E1H
SYSCR2 EQU 00E2H
WDMOD EQU 005CH
LD
(SYSCR2),
X
−
11
−
−
−
−
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
;
SET
3, (SYSCR1)
; Changes f
SYS
from fc to fs.
RES
7, (SYSCR0)
; Disables high-frequency oscillation.
X: Don’t care,
−
: No change
Detects stopping of warm-up timer.
fc
fs
Counts up by fs
<XEN>
X1, X2 pins
XT1, XT2 pins
<XTEN>
Warm-up timer
End of warm-up timer
<SYSCK>
System clock f
SYS
Enables
low
frequency
Clears and starts
warm-up timer
End of warm-up timer
Chages f
SYS
from fc to fs
Disabiles
high frequency
Counts up by f
SYS