Hi Russell,

Many thanks for taking the time to give me a lending hand. I've tried the below, but have 2 problems.

1. When #3 is assigned to pulse_count, the PCA does not stop after 3 pulses. It produces pulses endless.
2. Tried 4 Frequencies ( 1 ~ 4 Khz ), but the frequencies are not correct.

Any suggestions ?

The Code :

.aseg __code, code

.ORG 0000H
LJMP MAIN

.ORG 0033H
LJMP PCA_INTERRUPT

MAIN:

MOV P0,#0FFH
MOV P2,#0H
MOV P1,#0H
MOV RELOAD_INDEX,#1
ACALL PCA_INIT
SJMP $

PCA_INIT:
MOV CMOD,#02H
MOV CH,#00
MOV CL,#00
MOV CCAPM0,#04DH
MOV CCAP0L,#.LOW(1000)
MOV CCAP0H,#.HIGH(1000)
CLR P1.3
SETB EC
SETB EA
SETB CR
RET

PCA_INTERRUPT:
CLR CCF0
PUSH ACC
PUSH PSW
PUSH DPH
PUSH DPL
PUSH B
MOV A,RELOAD_INDEX
CLR C
RL A
mov dptr,#reload_table
movc a,@a+dptr
mov b,a
mov a,reload_index
clr c
rl a
inc a
movc a,@a+dptr
xch a,b
add a,CCAP0L
mov CCAP0L,a
mov a,b
addc a,CCAP0H
mov CCAP0H,a
djnz pulse_count,isr_1

mov pulse_count,#3
inc reload_index

isr_1: ;berenkat!
POP B
POP DPL
POP DPH
POP PSW
POP ACC
RETI


RELOAD_TABLE:
.DCI 3125,1563,1042,781 ;1 ~ 4 kHZ

.aseg __data,data

.org 20H

Pulse_Count .DSB
Reload_Index .DSB