No, 100 is correct.  If you look in the source code ZIP file, you will=20
see that he sets PR2 to 100(-1), so Timer2 counts 0-99.  When Timer2 =3D=20
CCPR1L, the output turns off. A value of 100 in CCPR1L means it will=20
never turn off.




On 1/4/2015 8:29 AM, Justin Richards wrote:
> Porting Roman's DC_motor_xtal.c (from
> http://www.romanblack.com/onesec/DCmotor_xtal.htm ) to assembly and have =
a
> question re CCPR1L.  Referring to the code snippet below ... he uses a
> setting of 100 for CCPR1L for full power.
>
> Is it possible he intended to use 255 and was thinking 100% so entered 10=
0.
>
> I suspect it is not possible to know exactly without asking the author bu=
t
> it appears to be a typo and hope those familiar with PWM may shed some
> light.
>
> <snip>
> #define  MOTOR_PROP_GAIN  10
> <snip>
> if(mpos < rpos)   // if motor lagging behind
>    {
>      mlag =3D (rpos - mpos);                            // find how far i=
t's
> lagging behind
>      if(mlag >=3D (100/MOTOR_PROP_GAIN)) CCPR1L =3D 100;  // full power i=
f is
> too far behind
>      else CCPR1L =3D (mlag * MOTOR_PROP_GAIN);          // else adjust PW=
M if
> slightly behind
>    }
> <snip>
>
> For the un-initiated, Roman has published some excellent detailed project=
s.
>
> Justin

--=20
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