Samsung S3F80JB User Manual
Page 268
S3F80JB
COUNTER
A
12-7
PROGRAMMING TIP — To generate a one-pulse signal through P3.1
This example sets Counter A to the one shot mode, sets the oscillation frequency as the Counter A clock source,
and CADATAH and CADATAL to make a 40
µs width pulse. The program parameters are:
40 us
— Counter A is used in one-shot mode
— Oscillation frequency is 4 MHz ( 1 clock = 0.25
µs)
— CADATAH
=
40
µs / 0.25 µs = 160, CADATAL = 1
— Set P3.1 C-MOS push-pull output and CAOF mode.
— 44
pin
package
ORG
0100H
;
Reset
address
START:
DI
•
•
LD
CADATAH,# (160-2)
; Set 40 ms
LD
CADATAL,# 1
; Set any value except 00H
;
LD
P3CON,#11110010B
; Set P3 to C-MOS push-pull output.
;
Set
P3.1
to
REM
output
;
LD
CACON,#00000001B
; Clock Source
→ Fosc
;
Disable
Counter
A
interrupt.
;
Select
one
shot
mode
for
Counter
A.
;
Stop
Counter
A
operation.
;
Set
Counter
A
Output
Flip-Flop
(CAOF)
high
LD
P3,#80H
; Set P3.7(Carrier On/Off) to high.
•
•
•
Pulse_out:
LD
CACON,#00000101B
; Start Counter A operation
;
to
make
the
pulse
at
this
point.
• ;
After
the
instruction
is
executed,
0.75
ms
is
required
• ;
before
the
falling edge of the pulse starts.
•