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talamahahahe
Joined: 15 Feb 2015
Posts: 39
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| Pic 16f887 and Srf04 ??? |
 Posted: Tue Apr 07, 2015 9:55 am |
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Hello everybody
I have a project combine Pic 16f887 with 3 ultrasonic sensor (srf04) to detect object...Whether i can use features ext on-change RB0 interrupt and timer 1 interrupt ??? |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Tue Apr 07, 2015 12:42 pm |
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What driver are you using for the SRF04 ? Post a link to it.
We can look at the driver to see if it can tolerate interrupts. |
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talamahahahe
Joined: 15 Feb 2015
Posts: 39
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| Posted: Wed Apr 08, 2015 2:49 am |
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thank so much for your reply
actually i don't have a driver for srf04, I just use pic control srf04 like this page http://www.robot-electronics.co.uk/htm/srf05tech.htm
when i use pic with just one srf04 to measure distance, everything is ok... i use on-change b interrupt and timer 1.....But my problem is i want to control 3 srf04 by this way and i failure...whether i can use on-change b interrup for 3 srf04 and just one timer 1 to count time |
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Mike Walne
Joined: 19 Feb 2004
Posts: 1785
Location: Boston Spa UK
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| Posted: Wed Apr 08, 2015 3:10 am |
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You're not giving us much to work on.
Please:-
1) Show (or describe) your schematic.
2) Explain how you are trying to use the three sensors.
3) Post some code.
Mike |
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talamahahahe
Joined: 15 Feb 2015
Posts: 39
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| Posted: Wed Apr 08, 2015 5:51 am |
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oh i fogot, sorry everybody
now, i will show use shematic and my code 
like a picture srf04 have 4 pin, 2 pin for vcc and gnd, 2 pin for trigger and echo. i connect pin trigger of srf04 A to pin_C0,and srf04 B to pin_c1. pin echo of srf04 A to pin b0 and pin echo srf04 B to pin B1.
first,pic make a pulse >10us for pin trigger of srf04, srf04 will pull up echo pin...distance is a time when echo is high.
this is a timing diagram
and this is code....i use on-change RB and timer ,ì use 1 srf04,it's ok,...but when i use 2 srf04, it not run right
| Code: |
#INCLUDE <16F887_REG.C>
#INCLUDE <16F887_LCD.C>
INT16 DATA1=0,DATA2=0;
#INT_RB
VOID RB_ON_CHANGE_INTERRUPT()
{
IF((INPUT(PIN_B0)==1)) {TMR1H=0;TMR1L=0;TMR1ON=1;} //IF ECHO PIN OF SRF04 A GO TO HIGH THEN TURN TIMER1 ON
ELSE IF((INPUT(PIN_B0)==0)) //ELSE IF ECHO PIN GO TO LOW THEN TURN TIMER1 OFF AND CALCULATE DISTANCE FROM DATA1
{
TMR1ON=0;
DATA1=TMR1H<<8;
DATA1=DATA1|TMR1L;
DATA1=DATA1/58;
}
IF((INPUT(PIN_B1)==1)) {TMR1H=0;TMR1L=0;TMR1ON=1;} //IF ECHO PIN OF SRF04 B GO TO HIGH THEN TURN TIMER1 ON
ELSE IF((INPUT(PIN_B1)==0)) ////ELSE IF ECHO PIN GO TO LOW THEN TURN TIMER1 OFF AND CALCULATE DISTANCE FROM DATA2
{
TMR1ON=0;
DATA2=TMR1H<<8;
DATA2=DATA2|TMR1L;
DATA2=DATA2/58;
}
}
VOID MAIN()
{
LCD_INIT();
TRISB=0XFF;
TRISC=0X00;
IOCB=0XFF;
GIE=1;PEIE=1;RBIE=1;RBIF=0;
TMR1ON=0;TMR1CS=0;T1CKPS1=1;T1CKPS0=0;TMR1GE=0;
TMR1H=0;TMR1L=0;
WHILE(TRUE)
{
OUTPUT_HIGH(PIN_C0); //MAKE A FULSE TRIGGER >10US TO ACTIVE SRF04 A
DELAY_MS(15);
OUTPUT_LOW(PIN_C0);
OUTPUT_HIGH(PIN_C1); //MAKE A FULSE TRIGGER >10US TO ACTIVE SRF04 B
DELAY_MS(15);
OUTPUT_LOW(PIN_C1);
LCD_GOTOXY(0,0);
LCD_WRITE(DATA1/100 +0X30,1);
LCD_WRITE(DATA1%100/10 +0X30,1);
LCD_WRITE(DATA1%10 +0X30,1);
LCD_GOTOXY(13,0);
LCD_WRITE(DATA1/100 +0X30,1);
LCD_WRITE(DATA2%100/10 +0X30,1);
LCD_WRITE(DATA2%10 +0X30,1);
}
}
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Mike Walne
Joined: 19 Feb 2004
Posts: 1785
Location: Boston Spa UK
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| Posted: Wed Apr 08, 2015 7:37 am |
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This is not very helpful.
| Quote: | | and this is code....i use on-change RB and timer ,ì use 1 srf04,it's ok,...but when i use 2 srf04, it not run right |
1) Tell us what's going wrong.
2) What values you're expecting, and the ones you're getting.
3) Tell us what tests you've done.
4) What happens say if you just remove the pulse for sensorA but leave the detection part in place.
5) ................
Mike |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19498
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| Posted: Wed Apr 08, 2015 7:46 am |
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My guess would be cross pickup....
Think about it. He is showing all the sensors using interrupt on change on the single port, and all enabled.
When he triggers the first transmission, and waits, he will get a little later the other sensors picking up the outgoing pulse, and then all three picking up the return. You can't use multiple ultrasonic receivers like this. You have to disable the ones you don't want to use.
Feed the inputs from all three sensors, through a 4 to 1 line multiplexer. Connect the output from this to a single interrupt. Then select the unit you want to use using the multiplexer, pulse it's transmitter, and handle the return just as for a single unit. Then when this has been done, switch the multiplexer, and use the second unit, and so on. |
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