Chief Delphi - Finding servo location?

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ForgottenSalad

23-02-2006 21:30

Finding servo location?

Just as a quick question, seeing as I never got to test my code, would getting the location of the servo be as simple as

Code:

printf("Servo Location is... %d\r", pwm01)

or would I have to do something more to find where it is betweeen 0 and 255...?

bush	23-02-2006 21:38

Re: Finding servo location?

that works

Joe Ross

23-02-2006 22:10

Re: Finding servo location?

Code:

printf("Servo Location is... %d\r", (int)pwm01)

JJG13

24-02-2006 16:21

Re: Finding servo location?

Quote:

Originally Posted by ForgottenSalad

Just as a quick question, seeing as I never got to test my code, would getting the location of the servo be as simple as

Code:

printf("Servo Location is... %d\r", pwm01)

or would I have to do something more to find where it is betweeen 0 and 255...?

First of all what are you trying to do? If you are setting a value to pwm01 and then printing it out later, this should work. However, you can't physically read the current position of the servo motor. Neither the hardware or software support this.

rodgadashruba

26-02-2006 19:18

Re: Finding servo location?

Quote:

Originally Posted by JJG13

However, you can't physically read the current position of the servo motor. Neither the hardware or software support this.

wait so there is no way to tell where the camera, like to read what position the tilt servo is at?

bush	26-02-2006 19:20

Re: Finding servo location?

You can. Just read the value of the PWM - in Kevin's code, the position is in the variable TILT_SERVO and PAN_SERVO

Tom Bottiglieri

26-02-2006 19:21

Re: Finding servo location?

If you are using the onboard motor control (PWM) to move the camera servos, you can put that printf right after the line that modifies that outputs value (make sure it is before the PutData !!)

If you are using the servo controller on the camera, you will have to ask the camera for what the current servo value is.

rodgadashruba

26-02-2006 19:47

Re: Finding servo location?

Quote:

Originally Posted by bush

You can. Just read the value of the PWM - in Kevin's code, the position is in the variable TILT_SERVO and PAN_SERVO

well i tried that in user routines, in the default code funtion. the code compiles just fine but when i add int he comman

int testTest = PAN_SERVO ;
or
static int testTest = PAN_SERVO;

i get syntax errors
is there a way to access these varible outside of tracking.c?

Bharat Nain

26-02-2006 20:05

Re: Finding servo location?

Quote:

Originally Posted by rodgadashruba

Paste the whole file where you put this line of code.

rodgadashruba

26-02-2006 20:24

Re: Finding servo location?

1 Attachment(s)

alright its attached
its down where it is commented out for the aim up code

ForgottenSalad

26-02-2006 20:44

Re: Finding servo location?

Quote:

Originally Posted by rodgadashruba

alright its attached
its down where it is commented out for the aim up code

Don't you have to declare the variable andrew OUTSIDE the routine?

That might be it, then again, I could be wrong.

(code trimmed out to point out lines in question)

Code:

void Default_Routine(void)

{

int shooter;

// aim up code... WOOT

// ok so find the value of pwm1 to line up the robot.. should be easy enough

static int Andrew = PAN_SERVO;

rodgadashruba

26-02-2006 20:48

Re: Finding servo location?

I thought that was it but shooter is declared..
i will try it out tho

rodgadashruba

26-02-2006 20:55

Re: Finding servo location?

wow alright.. so turns out i fail at remembering basic C...
had to declare Andrew at the top of default routines..

Matt Krass

26-02-2006 21:31

Re: Finding servo location?

Keep in mind this tells you where the servo is being commanded to go, not where it is, in most case they're synonomous, but if you're caught on something, or doing a lot of tracking this value could introduce lag which creates oscillations, making it worse, feedback loops, a constantly increasing error, all kinds of bad stuff. Just remember thats where it's trying to be and 98% of the time it should be there.

ForgottenSalad

26-02-2006 21:45

Re: Finding servo location?

Just out of curiosity, is there a better way, then?

Eko	26-02-2006 21:59

Re: Finding servo location?

Other than having a rotary potentiometer or something on it...

Nope =)

Keith Watson

26-02-2006 22:20

Re: Finding servo location?

Quote:

Originally Posted by rodgadashruba

Yes. Since PAN_SERVO is in a #define statement in tracking.h you just need to make sure you include that .h file. Or just directly use pwm01 if that is what your #define is set to.

Keith Watson

26-02-2006 22:30

Re: Finding servo location?

Quote:

Originally Posted by Matt Krass

Please note that the only thing Matt is pointing out are possible error conditions which should not be encountered in normal operation.

1) Do not command your servo to go into a position where the servo's movement is physically limited.

2) Setting the pwm value is where the servo will end up. This is pretty accurate. If you are worried about the speed in which the servo gets to the commanded position versus the speed of your processing loop then use the Hitec specification for the speed of your servo to figure out if you need a delay.

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