Re: strange tpu pwm problem

 Thanks for your reply Eric, 
I think you are the one from the company that does everything 
imaginable with that tpu.
I never thouth of that low power issue, I will consider it. 
But when these two lines are added to my code 

tpub->TPUMCR3.B.EPSCKE = 0x01;//epsck enable
tpub->TPUMCR3.B.EPSCK = 0x1f;//system clock/64

which makes the system clock divided by 64 instead of 32 (with new 
period value of 17500 now of course) it works fine. 
I did not know that would solve the problem when I first post the 
message. Anyway the problem is solved but it is now more strange with 
this new issue.


--- In [email protected], Eric McRae <eric@e...> wrote:
> Is it possible that your outputs are configured for low power drive 
and 
> that the signal is just not able to climb to logic 1 below 6% high 
time?
> 
> fatih_lokumcu wrote:
> 
> > Hello,
> > I have a strange problem. I use the tpu pwm function to
> > produce a 20 hz pwm which varies between %5 and %10 duty cycles 
for
> > servo control.
> > I have metrowerks mpc5xx edition 8.0 with phycore 565 board.
> > It works fine between %6 and %10 duty cycles but all of the lower
> > duty cycle commands lead to a %0 duty cycle. (which has a low 
time of
> > 250 ns.)
> >
> > Here is my code:
> >
> > UINT16 period ;
> > UINT16 hightime;
> > struct TPU3_tag *tpub = &TPU_B;
> >
> > void InitServo(void) {
> >       period = 35000;
> >       hightime = 2232;
> > tpu_pwm_init
(tpua,0,TPU_PRIORITY_HIGH,period,hightime,TPU_PWM_TCR1);
> >
> > }
> >
> > when TCR1 is used with  PSCK = 0 it it divides the 56 mhz clock 
by 32
> > and period value of 35000 makes the wave 20 hz. So to produce the 
pwm
> > between 1ms and 2ms duty cycle hightime must be between 3500 and 
1750.
> > The code above works fine until the hightime is set below 2232. I
> > tried to change the hightime with tpu_pwm_update function but 
nothing
> > has changed. There is no scheduling problem since no other tpu
> > funtion is used.
> > Also, the same code works with phycore mpc555 (with period = 25000
> > for 40 mhz of course.) without any problem.
> >
> > Is there any explaination for this?
> >
> > Thanks in advance,
> >
> > Fatih Lokumcu.
> >
> >
> >
> >
> >
> >
> > -----------------------------------------------------------
> > To learn more about Freescale Microcontrollers, please visit
> > http://www.freescale.com/mcu
> >
> >
> >
> >
> >
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> 
> -- 
> Eric McRae, Electro-Logic Machines, Inc.
> 511 Root St., Port Townsend WA, 98368
> Phone/Fax: 360.379.0969, http://www.elmi.com




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