| ??? 02/06/06 02:47 Modified: 02/06/06 03:00 Read: times |
#109257 - schematic and code Responding to: ???'s previous message |
Suresh said:
I too prefer doing it with a microcontroller for accuracy.
But, to my knowledge i thought, i could use an interrupt to start dispensing. and i can program the timer. But iam not aware of how the Timing could be adjusted manually when a microcontroller is used. Any suggestions. You could try the following circuit: 
(Pin1 of ISP header goes to P1.7) This could be the code (not tested so far): $nomod51
$include (89s52.mcu)
org 0
sjmp begin
org 002bh
;initialize
begin: mov auxr,#00011001b ;reset pin is input
mov tmod,#00000001b ;timer 0 in modus 1
;Total delay is
;number 'z' (BCD-
;switches) times
;10msec delay of
;timer 0
;reads 'start' and
;BCD switches
start_pressed?: clr p1.4 ;strobe watchdog
mov c,p0.2 ;read 'start'
setb p1.4 ;strobe watchdog
;'start' pressed?
jc start_pressed? ;No!
;'start' is pressed:
mov a,p0 ;read "1"
swap a ;eases layout
cpl a ;true data
anl a,#00001111b ;low nibble needed
mov r0,a ;store "1" in r0
mov a,p2 ;read "10","100"
cpl a ;true data
mov r1,a ;store it in r1
swap a ;eases layout
anl a,#00001111b ;low nibble needed
mov b,#10 ;load #10 into b
mul ab ;a = "10" x 10
add a,r0 ;add r0 ("1")
mov r0,a ;store it in r0
mov a,r1 ;now we need "100"
anl a,#00001111b ;low nibble needed
mov b,#100 ;load #100 into b
mul ab ;a = "100" x 100
add a,r0 ;add r0
mov r0,a ;low byte in r0
mov a,#0 ;carry?
addc a,b ;add carry to b
mov r1,a ;high byte in r1
;r1=0?
jnz activate_relay ;r1<>0!
;r1=0!
mov a,r0 ;r0=0?
jz start_released? ;r0=0 and r1=0!
;means z=0!
;r0<>0 or r1<>0!
;means z<>0!
activate_relay: clr p0.0 ;turn on relay
;initialize timer
timer_delay: mov th0,#220 ;reload high byte
mov tl0,#15 ;reload low byte
setb tr0 ;start timer 0
clr p1.4 ;strobe watchdog
;timer busy?
timer_busy?: jnb tf0,timer_busy? ;timer busy!
;10msec delay over
clr tr0 ;stop timer 0
clr tf0 ;clear overfl. flag
setb p1.4 ;strobe watchdog
;decrement z
mov a,r0 ;
clr c ;
subb a,#1 ;a=r0-1
mov r0,a ;low byte of z=z-1
;into r0
mov a,r1 ;carry?
subb a,#0 ;
mov r1,a ;high byte of z=
;z-1 into r1
;r1=0?
jnz timer_delay ;r1<>0!
;r1=0!
mov a,r0 ;r0=0?
jnz timer_delay ;r0<>0!
;r0=0 and r1=0!
;means z=0!
setb p0.0 ;turn off relay
start_released?: clr p1.4 ;strobe watchdog
mov c,p0.2 ;read 'start'
setb p1.4 ;strobe watchdog
;'start' released?
jnc start_released? ;No!
;'start' released!
;initialize waiting
;loop
mov r1,#103 ;'start' released
waiting_loop_1: mov r0,#255 ;for 0.2 sec?
waiting_loop_2: clr p1.4 ;strobe watchdog
mov c,p0.2 ;read 'start'
setb p1.4 ;strobe watchdog
;still released?
jnc start_released? ;No!
;still released!
djnz r0,waiting_loop_2 ;repeat loop 2
djnz r1,waiting_loop_1 ;repeat loop 1
ljmp start_pressed? ;'start' released
;for at least
;0.2sec!
end
Kai |
