Discussion in "8051 Discussion Forum" started by    neil03    Aug 5, 2009.
Wed Aug 05 2009, 07:33 PM
#1
hi im working on a PWM signal output from a microcontroller using at89c2051.
The status of my project is that I successfully produce the desired PWM signal but, my problem is I cannot stop the process of stopping the PWM signal when I switch it to stop.
____________________________________________________________________
The algorithm of the program is simply like this

1. when switch 1 is pressed the microcontroller produce a PWM signal
2. when switch 2 is pressed the micrcontroller stop producing the signal or clearing the output pin of the MC.
____________________________________________________________________
Now as I have said above I successfully produce the desired PWM signal but when I switch it to stop. The PWM output pin remains to produce the PWM signal..Honestly this program is really working previously and I have used this program several times ago but now when I try to burn it on a new microcontroller it doesnt respond to its previous state.. I also try to change different at89c2051, 3 mc to be exact, but still im getting the same problem..
Im thinking that the maybe the programmer have a defect or something, but im not so sure and I dont want to take the risk of buying a new programmer cause it costs alot.

Can anybody help me to find what is the problem causing this and please teach me to resolve it..I have attach the program and the schematic of my project. please help me people thank you so much.
 switch1   EQU P1.2     ; switch for PWM
 switch2   EQU P1.3		; switch for stop PWM signal
 PWMPIN    EQU P3.4      ; PWM output pin 

ORG 00H
SJMP Main

org 0BH ;Vector address for Timer0
AJMP TIMER_0_INTERRUPT ;jump to ISR routine

;Main code
Main:
JB  P1.2, PWM_INI ; go to PWM setting 1
sjmp Main

PWM_INI:         ;initiate PWM
acall PWM_SETUP 
here:
JB   P1.3, STOP;
SJMP here ;

STOP:
clr PWMPIN
sjmp Main;


PWM_SETUP:
        MOV TMOD,#00H           ; Timer0 in Mode 0
        MOV R7, #240            ; Set pulse width control
        ; The value loaded in R7 is value X as
        ; discussed above.
        SETB EA         ; Enable Interrupts
        SETB ET0                ; Enable Timer 0 Interrupt
        SETB TR0                ; Start Timer
        RET

TIMER_0_INTERRUPT:
        JB F0, HIGH_DONE        ; If F0 flag is set then we just finished
                                ; the high section of the
LOW_DONE:                       ; cycle so Jump to HIGH_DONE
        SETB F0                 ; Make F0=1 to indicate start of high section
        SETB PWMPIN             ; Make PWM output pin High
        MOV A, #0FFH            ; Move FFH (255) to A
        CLR C                   ; Clear C (the carry bit) so it does
                                 ; not affect the subtraction
        SUBB A, R7              ; Subtract R7 from A. A = 255 - R7.
        MOV TH0, A              ; so the value loaded into TH0 + R7 = 255
		CLR TF0                 ; Clear the Timer 0 interrupt flag
        RETI                    ; Return from Interrupt to where
                                        ; the program came from
HIGH_DONE:
        CLR F0                  ; Make F0=0 to indicate start of low section
        CLR PWMPIN              ; Make PWM output pin low
        MOV TH0, R7             ; Load high byte of timer with R7
                                ; (pulse width control value)
        CLR TF0                 ; Clear the Timer 0 interrupt flag
        RETI                    ; Return from Interrupt to where
                                ; the program came from




END






[ Edited Wed Aug 05 2009, 07:35 PM ]
Wed Aug 05 2009, 07:51 PM
#2
well schematic is not so big to have a problem in it.

You can load a simple LED blink program to see if your controller is fine or not.

I think problem seems to be in program for making it non stop PWM. the reason is.. PWM works with timer so along with clearing of PWM pin, you should also clear TR0, and TF0 so that timer stops and interrupt flags can be cleared. and to start PWM again, you have the init function.

[Topic moved to 8051 Discussion forum]
Thu Aug 06 2009, 02:07 AM
#3
You'll also have to make sure the SW1 switch is off else the pwm generation will start again.
better implement sth like this....
Main:
JNB  P1.2, Main;check if START is pressed
JNB P1.3,PWM_INI ; go to PWM setting 1 if STOP not pressed
sjmp Main

Get Social

Information

Powered by e107 Forum System

Conversation

ExperimenterUK
Tue Jul 19 2016, 05:59 PM
@mhammad 64 bits is 8 bytes.
Tue Jul 19 2016, 07:56 AM
mhammad kassem
hello! i want to know how to use UART in mikroc , I want to receive 64 bits from another microcontroller and i dont know how to start my code to receive the 64 bits...any help?
ExperimenterUK
Mon Jul 18 2016, 08:32 PM
@meena.. are you still having trouble ?
Sat Jul 16 2016, 10:19 AM
Meena
problem in loading email address while registering.Please help
Sun Jul 10 2016, 02:50 PM
shockwave
could you please provide a sample code that controling LED using bluetooth HC-05 interfacing pic16f877a thank you!
Sun Jul 10 2016, 02:49 PM
shockwave
Help!
ExperimenterUK
Sat Jul 09 2016, 05:25 PM
@Santhana krishnan post in forum to discuss your problem
Thu Jul 07 2016, 09:26 AM
Santhana krishnan
Hi i program atmega 32 it was functiining corectly but now aref pins voltage 2.56 is droped to .85 volts also a ports input viltage also dropped so anologe inpit not funcitonig please help me to find out the problem
Thu Jul 07 2016, 09:24 AM
Santhana krishnan
Hi i program the atmega 32
Thu Jul 07 2016, 09:24 AM
Santhana krishnan
Hi

Downloads

Comments

adithyapaip
Thu Jul 21 2016, 05:45 PM
celu
Thu Jul 21 2016, 05:27 PM
Aiko
Wed Jul 20 2016, 01:51 PM
JorgeG
Sat Jul 16 2016, 07:19 PM
Piotrekk
Wed Jul 06 2016, 09:35 AM
dyoussef
Wed Jun 29 2016, 07:29 PM
sung7333
Tue Jun 28 2016, 06:23 AM
Bonolai
Fri Jun 24 2016, 06:02 AM

Online

Guests: 46, Members: 0 ...

most ever online: 182184
(Members: , Guests: 182184) on 06 Aug 2010: 05:37 AM

Members: 37775
Newest member: adithyapaip
Forum Activity
ExperimenterUK Avatar
Posted By ExperimenterUK
Sat Jul 23 2016, 07:14 PM
I found this datasheet, it is a type of driver.It ...
Piotrekk Avatar
Posted By Piotrekk
Fri Jul 22 2016, 10:12 AM
I found an old box of electronic components in the...
ExperimenterUK Avatar
Posted By ExperimenterUK
Thu Jul 21 2016, 07:37 PM
That is curious, but very likely a co-incidence.Th...
adithyapaip Avatar
Posted By adithyapaip
Thu Jul 21 2016, 07:18 PM
I am using keil to do everthing in 8051,when I was...
ExperimenterUK Avatar
Posted By ExperimenterUK
Thu Jul 21 2016, 07:14 PM
By far the easiest and cheapest way to talk to the...
ExperimenterUK Avatar
Posted By ExperimenterUK
Thu Jul 21 2016, 07:04 PM
The crystal on the programmer does not affect the ...
adithyapaip Avatar
Posted By adithyapaip
Thu Jul 21 2016, 06:06 PM
Hi Guys..i have a 8051 programmer which has 4mhz c...
Aiko Avatar
Posted By Aiko
Wed Jul 20 2016, 01:56 PM
ankitbajaj01 Avatar
Posted By ankitbajaj01
Wed Jul 20 2016, 04:49 AM
Dear All,Greetings!!!I want to develop Online moni...
sairfan1 Avatar
Posted By sairfan1
Tue Jul 19 2016, 09:56 PM
Now a days there are many smart locks available li...