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Kai Klaas
02/05/06 19:47
  02/05/06 20:00

Read: 1635 times

#109257 - schematic and code
Responding to: Suresh R'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):

                    $include (89s52.mcu)    

                    org 0
                    sjmp begin

                    org 002bh

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
                    jnz activate_relay      ;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

                    jnz timer_delay         ;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
                    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



List of 57 messages in thread
Circuit for dispensing unit      Suresh R      01/31/06 05:09      
   1.1 sec monoshot      Abhishek Singh      01/31/06 09:43      
      this thread is apin off from an earlier      Terry Lingle      01/31/06 13:07      
         yes      Steve M. Taylor      01/31/06 13:55      
         timing circuit      Suresh R      02/01/06 04:17      
   Monostable      Andy Neil      01/31/06 12:08      
   Yes.      Steve M. Taylor      01/31/06 13:06      
   Hello All      Suresh R      01/31/06 22:23      
      Description of the "Dispensing Unit"      Andy Neil      02/01/06 00:39      
         using micro      Suresh R      02/02/06 00:25      
            Microcontroller      Andy Neil      02/02/06 01:35      
               Pressure      Steve M. Taylor      02/02/06 03:51      
            What must your circuit can do?      Kai Klaas      02/02/06 07:17      
               0.1 sec      Steve M. Taylor      02/02/06 10:34      
                  but not with a potentiometer      Erik Malund      02/02/06 10:38      
                     Vernier      Steve M. Taylor      02/02/06 13:02      
                        and calibrate it how?      Erik Malund      02/02/06 13:14      
               Precision        Andy Neil      02/02/06 15:13      
                  Sure!      Kai Klaas      02/02/06 16:01      
                     Price      Andy Neil      02/02/06 17:06      
                        Less than 1      Kai Klaas      02/02/06 20:02      
                           levels of precision      Suresh R      02/03/06 05:01      
                              Please have a look into datasheet!      Kai Klaas      02/03/06 05:57      
                                 somewhere here there is a link      Erik Malund      02/03/06 06:51      
                                    Details?      Kai Klaas      02/03/06 07:17      
                                       I recall that in an earlier thread      Erik Malund      02/03/06 07:20      
                              Ooops.      Steve M. Taylor      02/03/06 09:49      
                              Blown Discharge PIN      Abhishek Singh      02/04/06 19:15      
                                 You can also let the smoke out of the      Terry Lingle      02/04/06 22:37      
                                    limits      Steve M. Taylor      02/05/06 06:13      
                                       dissapation      Terry Lingle      02/05/06 09:45      
                                          There must be a point.      Steve M. Taylor      02/05/06 10:31      
                                             Fusing the bonding wires      Terry Lingle      02/05/06 13:59      
                                                History making      Steve M. Taylor      02/05/06 14:47      
                                                Current limiting      Kai Klaas      02/07/06 06:42      
                                 I do go through      Suresh R      02/07/06 01:50      
            schematic and code      Kai Klaas      02/05/06 19:47      
               codes      Suresh R      02/07/06 00:32      
                  Instruction Description      Andy Neil      02/07/06 04:28      
                     not quite      Erik Malund      02/07/06 06:09      
                        Pedantic      Andy Neil      02/07/06 07:12      
                           is that not the pot calling the kettle b      Erik Malund      02/07/06 07:17      
                              Of course not!      Andy Neil      02/07/06 07:31      
                  Answers      Kai Klaas      02/07/06 07:55      
                     Re: codes and shcematic      Suresh R      02/10/06 03:55      
                        Recommendations      Kai Klaas      02/10/06 07:05      
                           Decimal switches - how to start C      Erik Malund      02/10/06 08:09      
      LM555 pin 2 wired wrong.      Charles Bannister      02/01/06 04:45      
         ... and the LED?      Andy Neil      02/01/06 05:31      
            i'm sure thts not the circuit      Abhishek Singh      02/01/06 06:38      
            Astable??      Kai Klaas      02/01/06 11:46      
               I wondered who'd spot that first...      Andy Neil      02/01/06 12:47      
   Damaged?      Kai Klaas      02/01/06 11:51      
      And Andy's correction      Steve M. Taylor      02/01/06 12:03      
         Absolutely!      Kai Klaas      02/01/06 12:24      
   one shot in the foot      Erik Malund      02/01/06 12:31      
      Need not to work unreliably      Kai Klaas      02/02/06 07:10      

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