servo motor resets 16f877a

[Acetronics2]

Hi, Burak

THIS could be a geat help :

http://www.parallax.com/Portals/0/Do...ic/Signals.pdf

Alain

[burak450]

I am trying to design an object tracker (only left and right) and I am using phototransistors by using two analog inputs.I have to explain my problem more clear.When I turn power on servo tracks object but after a while sometimes pic resets itself or servo motor suddenly stops.I hope
I explained it clearly.What do you suggest? Here is my design.When you see the design there is a lcd.I use it for watching the values of analog input.When servo rotates,brightness of lcd changes (getting brighter or darker)...I think thats another weird thing...

[skimask]

When servo rotates,brightness of lcd changes (getting brighter or darker)...I think thats another weird thing...

Doesn't that right there tell you something about the quality of your power supply?
Let's see...if I'm driving down the road, and my headlights change brightness, does that tell me anything about the electrical power in the car? If I'm sitting in my living room at night reading a book and the room's lights either dim or get brighter, would that tell me something about the local power grid?

I don't see ANY capacitors in there, either across Vdd and Vss or across your servo's power supply. I don't see what kind of power you are supplying this circuit with. I don't see a lot of anything.

Ya know, for that matter, we haven't seen your code yet... Who knows...maybe it is actually a firmware problem...

[Archangel]

I would agree with Skimask re: the capacitors and your power supply, I would add, disable Brown Out Reset in your config statement so PIC does not reset, I would further suggest you change your reference to God Blessed servo, just remembering something Moses said to Pharoe, "by your own words . . ." Cause if he Damns it, it's toast.

[aratti]

Hi, Burak from your schematic and your explanation I understand that is just a power supply problem! Add 10nF capacitor to the Vdd pic pin. Since surely you are using battery, my suggestion is that you use a two 9 volts batteries in parallel to a 7805 and use its output as power supply for your project. One way to check quickly that current failure is your problem, can be achieved simply removing (disconnect it) the backligth of your lcd, and very likely the problem will disappear as long as the present battery will be able to supply the required energy

[burak450]

i should repeat that=Lcd brightness doesnt change at normal work. when servo moves than it goes high or low...
my power supply is that.

switching adapter
input:ac 100-240V-50hz 0.36A
output:dc 5v--2.5A

and my program is that

DEFINE LCD_DREG PORTB
DEFINE LCD_DBIT 0
DEFINE LCD_RSREG PORTB
DEFINE LCD_RSBIT 4
DEFINE LCD_EREG PORTB
DEFINE LCD_EBIT 5
DEFINE LCD_BITS  4
DEFINE LCD_LINES 2
DEFINE OSC 4                                                                       
DEFINE ADC_BITS     8      
DEFINE ADC_CLOCK  3     
DEFINE ADC_SAMPLEUS 100
SYMBOL F=PORTA.0
SYMBOL G=PORTA.1
alta var byte
usta var byte
altb var byte
ustb var byte
ADCON1=2
TRISA=3
TRISB=0
PORTB=0
TRISC=0
LCDOUT $FE,1 
pause 4000
adcin  0,ALTa
ADCin  1,usta

t var byte
i var byte
T=150

yap:




adcin  0,altb
ADCin  1,ustb






if  ((((usta+10)*100)/(ustb+10)))>135 then 
T=T+15
endif

if (((alta*100)/altb))>135 then 
T=T-15
endif


gosub motor





  

LCDOUT $fe,2,#usta," ",#ustb," ",#altA," ",#altb   

goto yap

motor:
for i=0 to 25
PULSOUT PORTC.2,T
PAUSEUS 20000-(T*10)
next
return

end

[aratti]

Check power supply wiring, especially the connector, install 1000 uF 16V electrolytic capacitor and 10 nF on your pic power pin

[skimask]

For grins, try changing your BYTE values to WORDs and see what happens.
Might be overflowing the byte values somewhere killing the program somehow someway.

[Acetronics2]

Hi, Burak

I'm curious to know which testboard you use ...

16F877A , LCD on PortB ... that sounds quite familiar.

So, the question is ... Where do you ( geographically ) take the servo 5v supply from ???

Alain

[Bruce]

Use a separate power supply for your servo.