> -----Original Message-----
> From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf
> Of yamanoor sairam
> Sent: 01 March 2012 18:19
> To: Microcontroller discussion list - Public.
> Subject: Re: [PIC]: Servo motor control - 12F675
>=20
> Hello All,
>=20
> I apologize for not getting back to the list to let you know whether I go=
t
> this problem solved. Unfortunately, I could not achieve speed control of
> my servo. All I am able to do is make my servo to known angles and known
> rates.
>=20
> To recap, I am trying to achieve speed control of my servo using PIC12F67=
5.
>=20
> There seems to be a problem is using the Hitech C delay functions. You
> cannot pass variables to the Hitech C delay functions.
>=20
> Hence I had to work around something like:
>=20
> while(i>0)
> {
>=20
> __delay_us(1);
> }
> Where i is the variable meant for changing the time delays. As suggested
> on this list earlier, I had even tries using for loops. But I was not
> successful at all. I read somewhere that a possible reason for the proble=
m
> could be that it is not possible to produce very small time delay cycles
> like 1 microsecond and hence I decided to go in steps of 10 microseconds.
> But neither for loops nor while loops are fixing my issue of time delay.
>=20
> Since the time delay is not perfect, my voltage regulator is boiling and
> the servo is not spinning at all.
>=20
> If I switch my compiler from Hitech to CCS, will it solve my problem? All
> I need is a function where I can pass a variable as an argument to the
> delay function. I am nervous to switch the compiler because while
> conducting the experiments, I switched to the MikroC IDE. I got frustrate=
d
> with the fact that I couldn't set config words like I could do in MPLAB.
>=20
> I tried even setting macros for time delays as suggested in one of the
> microchip forums. I got a lot of compiler errors and I just got frustrate=
d
> out of not being able to fix this problem.
>=20
> I am looking forward to hearing your suggestions on fixing the time delay
> issue.
>=20
> Sai


My suggestion is to abandon the use of software delays for this application=
; it's a horrible way of doing things that results in unreliable spaghetti =
code.

Instead use a hardware timer, and toggle your servo PWM in the timer interr=
upt.  You can handle the switch sensing and speed/position control within t=
he main loop or within the timer interrupt.  You get the advantage of being=
 able to run the PWM all the time if you want, which means your servo will =
now hold in the last location and you can run any other code you need from =
within the main loop without all the clunky software delays.

Cheers

Mike

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