servo motor control through potentiomer code error

[e.hamza]

i am supposed to control a servo motor movement using this code through the resistance change of a potentiometer
am using a pic 16f877A and ccs pic compiler

The code i've reached so far is

void main() {

int value,x1;

setup_adc_ports(ALL_ANALOG); setup_adc(ADC_CLOCK_INTERNAL); setup_psp(PSP_DISABLED); setup_spi(SPI_SS_DISABLED); setup_timer_0(RTCC_INTERNAL|RTCC_DIV_1); setup_timer_1(T1_DISABLED); setup_timer_2(T2_DISABLED,0,1); setup_comparator(NC_NC_NC_NC); setup_vref(FALSE);

while (1) { set_adc_channel(0); delay_us(10);

value=read_adc();

x1 = value +1000 ;

output_high(PIN_b0); delAY_us(x1); output_low(PIN_b0); delay_ms(20); } }

any ideas guys ?please :S

 

[FvM]

You didn't report an error or problem.

 

[e.hamza]

yea there is no actual error it's just that it's not working :S
but i don't know why do u have any idea ?

 

[FvM]

Is the output switching at all? To check your code, we would need the full source, including all #fuses and preprocesor commnds. You should also tell the CCS C version.

 

[e.hamza]

these are the fuses :


#include <16F877A.h>
#device adc=10

#FUSES NOWDT //No Watch Dog Timer
#FUSES LP //Low power osc < 200 khz
#FUSES NOPUT //No Power Up Timer
#FUSES NOPROTECT //Code not protected from reading
#FUSES NODEBUG //No Debug mode for ICD
#FUSES NOBROWNOUT //No brownout reset
#FUSES NOLVP //No low voltage prgming, B3(PIC16) or B5(PIC18) used for I/O
#FUSES NOCPD //No EE protection
#FUSES WRT_50% //Lower half of Program Memory is Write Protected

#use delay(clock=20000000)
#use rs232(baud=9600,parity=N,xmit=PIN_C6,rcv=PIN_C7,bits=8)

the whole source is uploaded here
ex.rar
and the ccs v is 4

 

[FvM]

The oscillator configuration and #use delay statement don't fit. What's the real oscillator configuaration? You can check the processor speed with a simple LED blink program.

 

[e.hamza]

sorry but i didn't understand what did u mean ?

 

[FvM]

You have set low power oscillator and 20 MHz frequency. So all timings will be completely wrong.

 

[e.hamza]

thanx for ur help but still not the answer :S

 

[FvM]

thanx for ur help but still not the answer

The answer to which question?

You should correct your code according to the requirements of PIC processor hardware and CCS clock setup statements. And then show it again.

 

[e.hamza]

void main()
{
int value , x1 ;
setup_adc_ports(ALL_ANALOG);
setup_adc(ADC_CLOCK_DIV_64);
setup_psp(PSP_DISABLED);
setup_spi(SPI_SS_DISABLED);
setup_timer_0(RTCC_INTERNAL|RTCC_DIV_1);
setup_timer_1(T1_DISABLED);
setup_timer_2(T2_DISABLED,0,1);
setup_comparator(NC_NC_NC_NC);
setup_vref(FALSE);

while (1)
{
set_adc_channel(1);
delay_us(20);
value = read_adc();

x1 = value+1000 ;

output_high(PIN_b1);
delAY_us(x1);
output_low(PIN_b1);
delay_ms(20);
}
}

#include <16F877A.h>
#device adc=10

#FUSES NOWDT //No Watch Dog Timer
#FUSES HS //High speed Osc (> 4mhz)
#FUSES NOPUT //No Power Up Timer
#FUSES NOPROTECT //Code not protected from reading
#FUSES NODEBUG //No Debug mode for ICD
#FUSES NOBROWNOUT //No brownout reset
#FUSES NOLVP //No low voltage prgming, B3(PIC16) or B5(PIC18) used for I/O
#FUSES NOCPD //No EE protection
#FUSES WRT_50% //Lower half of Program Memory is Write Protected

#use delay(clock=20000000)
#use rs232(baud=9600,parity=N,xmit=PIN_C6,rcv=PIN_C7,bits=8)

this is the final code :S

 

[FvM]

O.K. I assume, that you have connected a 20 MHz crystal with respective capacitors and verified that the circuit is correct.

There's still a problem, because int has 8 Bit size in CCS C by default. You should write int16 instead.

 

[e.hamza]

i think that the problem is in variable declaration cause when i tried sitting the x1=1500;
it gave me the same problem so most likely the problem is in using the variable :S i think

 

[FvM]

i think that the problem is in variable declaration

Yes, I explained why.

 

[e.hamza]

void main()
{
#include <16F877A.h>
#device *=16
#device adc=10

#FUSES NOWDT //No Watch Dog Timer
#FUSES HS //High speed Osc (> 4mhz)
#FUSES NOPUT //No Power Up Timer
#FUSES NOPROTECT //Code not protected from reading
#FUSES NODEBUG //No Debug mode for ICD
#FUSES NOBROWNOUT //No brownout reset
#FUSES NOLVP //No low voltage prgming, B3(PIC16) or B5(PIC18) used for I/O
#FUSES NOCPD //No EE protection
#FUSES WRT_50% //Lower half of Program Memory is Write Protected

#use delay(clock=20000000)
#use rs232(baud=9600,parity=N,xmit=PIN_C6,rcv=PIN_C7,bits=8)

int16 value , x1;
setup_adc_ports(ALL_ANALOG);
setup_adc(ADC_CLOCK_INTERNAL);
setup_psp(PSP_DISABLED);
setup_spi(SPI_SS_DISABLED);
setup_timer_0(RTCC_INTERNAL|RTCC_DIV_1);
setup_timer_1(T1_DISABLED);
setup_timer_2(T2_DISABLED,0,1);
setup_comparator(NC_NC_NC_NC);
setup_vref(FALSE);

while (1)
{
set_adc_channel(1);
delay_us(10);
value = read_adc();

x1 = value+990 ;

output_high(PIN_b1);
delAY_us(x1);
output_low(PIN_b1);
delay_ms(19);
}
}

it worked just fine in simulation but when i programed the chip and tried it the servo would go to 90+ and stop there on it's own and the potentiometer doesn't work at all

 

[FvM]

I don't see a reason at first view. Does the servo control work with fixed delays?

 

[e.hamza]

void main()
{

setup_adc_ports(NO_ANALOGS);
setup_adc(ADC_OFF);
setup_psp(PSP_DISABLED);
setup_spi(SPI_SS_DISABLED);
setup_timer_0(RTCC_INTERNAL|RTCC_DIV_1);
setup_timer_1(T1_DISABLED);
setup_timer_2(T2_DISABLED,0,1);
setup_comparator(NC_NC_NC_NC);
setup_vref(FALSE);
while(1){
output_high(PIN_b1);
delAY_us(1200);
output_low(PIN_b1);
delay_ms(19);

delay_ms (1500) ;

}

}
when i used this code the servo would rotate one step and stop every time i connect the circuit :S

 

[BradtheRad]

Question:

Is this the same kind of servo used in radio control cars/ boats/ airplanes?

You control its position according to the length of a pulse sent to an input wire (which makes 3 wires in addition to the two supply wires).

Each pulse must be between 1-2 milliseconds long. The middle position is 1.5 mSec.

Pulses do not need to be any particular frequency.

That is how the servos I've worked with operate.

Or is it a stepper motor?

 

[e.hamza]

yes it's a aservo motor just like the one u 've described

 

[mac231991]

what servo motor are you using? can you post your schematic for the whole project? i am new on pic programming