Post by thread:Read PWM-In and Write PWM-Out without interrupt ?

> hello all PICers, > > I wish to decode the multiplexed frame of a R/C command in order to cont rol {Quote hidden}>an output as a PWM. Let me try to explain : > >The input of the PIC is a frame of 20 ms beginning with a synchronizing pulse >(3 to 4 ms ?), than a serie of 8 pulses of min 1ms, max 2ms. > >My PIC must : >* recognize the sync pulse >* count the pulse that is to be decoded (1 to 8). It will be given by >hardware or "programmation" of EEPROM registers >* measure it >* give it to the rest of the program > >* And all this should be done with an adequate accuracy while an independa nt >PWM output (50 to 100 Hz) is running ! >* AND with a PIC that has NO INTERRUPT FACILITIES (I wish to use a 12C509 SMD {Quote hidden}>since it is the smaller in 8 pins package) > >That may seem very simple to experienced people but not for me ;-) > >I planned to : >* run a timer as an absolute clock >* make to consecutive loops for "In stuff" than "Out stuff" >* in each loop, read the absolute clock at the timer, compute delta time ( = >duration), control any overflow of the timer, check if duration have haapened >... >-> I have to check the overall accuracy ... > >Any idea (or already done application :-) will be welcome ... > >Thanks a lot !!! > >Jean-Yves > > >

I already posted that, but it was while trying (unfortunately) to re-suscribe to the PICLIST ; so I don't know if this message had been correctly sent. A thousand of excuses if you already read it (but I got no answer :-(( >Here it was : > hello all PICers, > > I wish to decode the multiplexed frame of a R/C command in order to cont rol {Quote hidden}>an output as a PWM. Let me try to explain : > >The input of the PIC is a frame of 20 ms beginning with a synchronizing pulse >(3 to 4 ms ?), than a serie of 8 pulses of min 1ms, max 2ms. > >My PIC must : >* recognize the sync pulse >* count the pulse that is to be decoded (1 to 8). It will be given by >hardware or "programmation" of EEPROM registers >* measure it >* give it to the rest of the program > >* And all this should be done with an adequate accuracy while an independa nt >PWM output (50 to 100 Hz) is running ! >* AND with a PIC that has NO INTERRUPT FACILITIES (I wish to use a 12C509 SMD {Quote hidden}>since it is the smaller in 8 pins package) > >That may seem very simple to experienced people but not for me ;-) > >I planned to : >* run a timer as an absolute clock >* make to consecutive loops for "In stuff" than "Out stuff" >* in each loop, read the absolute clock at the timer, compute delta time ( = >duration), control any overflow of the timer, check if duration have haapened >... >-> I have to check the overall accuracy ... > >Any idea (or already done application :-) will be welcome ... > >Thanks a lot !!! > >Jean-Yves > > > >

I have uploaded some timing based 12c508 code (actually auto-sync RS-232) code with some discussion about the timer load/reload stuff. http://www.iversoft.com/piclist/code.html Look for file serial10.zip. This allows 'accurate' measuring of a start bit pulse +/- a few cycles at about 50 uS. (Simulated only :-) A little extra code should give you milli-second resolution... Good luck... Ralph Seyler Jean-Yves wrote: <<snip>> > > > > >My PIC must : > >* recognize the sync pulse

Thanks Ralph, I will have a look to your program (did you try it in "real world" now ?) But I recall you this is only 1 part of my 2 problems that are : 1) Measure input pulse 2) While doing output PWM ... I thought of a main program polling alternatively between 2 "main subroutines" : 1 for In and 1 for Out. But, for sure, I will loose accuracy (that should not too important for me since 1/64 ms should be enough) Thanks and Bye Jean-Yves {Quote hidden}>---------- >De : Ralph Stickley[SMTP:spam_OUTrstickleyTakeThisOuTDATALUX.COM] >RŽpondre ˆ : pic microcontroller discussion list >Date : mercredi 7 avril 1999 20:08 >A : .....PICLISTKILLspam@spam@mitvma.mit.edu >Objet : Re: Read PWM-In and Write PWM-Out without interrupt ? > >I have uploaded some timing based 12c508 code (actually auto-sync RS-232) >code >with some discussion about the timer load/reload stuff. > >http://www.iversoft.com/piclist/code.html > >Look for file serial10.zip. This allows 'accurate' measuring of a start bit >pulse +/- a few cycles at about 50 uS. (Simulated only :-) A little extra >code >should give you milli-second resolution... > >Good luck... > >Ralph > > >Seyler Jean-Yves wrote: ><<snip>> >> >> > >> >My PIC must : >> >* recognize the sync pulse >