This is a realtime data collection problem. Running on an OP7200. It drives an optical system and an observer pushes some buttons to change what they see. (or report what they see.)

Part of what they see is two LEDs alternating with each other in square wave fashion at a rate from 5 to 35 Hz. So the half-period is from 14.3 msec to 100 msec.

That part is in a simple costate:

costate flickerout always_on // create flicker here
{
waitfor(DelayMs(halfperiod));
digOut (ch1, 0); // LED1 off
digOut (ch2, 1); // LED2 on
waitfor(DelayMs(halfperiod));
digOut (ch1, 1); // LED1 on
digOut (ch2, 0); // LED2 off
}

Of course, early on, before the code got from 2 KB to 88 KB, there was NO perceptible "jiggle" as the observer pressed various pushbuttons tied to digital inputs. But now there are clear blips in this otherwise very clean looking signal.

I've been doing a lot of reading. It looks like I need to make this part of the code run pre-emtively. The need is for this:

- a square wave running from 5 to 35 Hz.
- the half-period needs to be set from outside the pre-emtive code.

I am having trouble getting my head around this. The SLICE statement looked like the way to go until I realized that it seems to gain control and prevent other things from happening. Of course I get the uneasy feeling that I there is something I just do not see.

I'd appreciate ideas. Anyone want a little work ??

thanks

bob moore

------------------------------------



(You need to be a member of rabbit-semi -- send a blank email to rabbit-semi-subscribe@yahoogroups.com )

rmoore007ri wrote:
> This is a realtime data collection problem. Running on an OP7200. It drives an optical system and an observer pushes some buttons to change what they see. (or report what they see.)
>
> Part of what they see is two LEDs alternating with each other in square wave fashion at a rate from 5 to 35 Hz. So the half-period is from 14.3 msec to 100 msec.
>
> That part is in a simple costate:
>
> costate flickerout always_on // create flicker here
> {
> waitfor(DelayMs(halfperiod));
> digOut (ch1, 0); // LED1 off
> digOut (ch2, 1); // LED2 on
> waitfor(DelayMs(halfperiod));
> digOut (ch1, 1); // LED1 on
> digOut (ch2, 0); // LED2 off
> }
>
> Of course, early on, before the code got from 2 KB to 88 KB, there was NO perceptible "jiggle" as the observer pressed various pushbuttons tied to digital inputs. But now there are clear blips in this otherwise very clean looking signal.
>
> I've been doing a lot of reading. It looks like I need to make this part of the code run pre-emtively. The need is for this:
>
> - a square wave running from 5 to 35 Hz.
> - the half-period needs to be set from outside the pre-emtive code.
>
> I am having trouble getting my head around this. The SLICE statement looked like the way to go until I realized that it seems to gain control and prevent other things from happening. Of course I get the uneasy feeling that I there is something I just do not see.
>
> I'd appreciate ideas. Anyone want a little work ??
>
> thanks
>
> bob moore
>

Make it run from an interrupt at 5ms. You can use timer B to generate
the int, I have the lib in my free libs page:

http://shdesigns.org/rabbit/freelibs.shtml

halfperiod would be the # of ms, 100 for 5hz, 15 for 35hz (approx)

void TimerBroutine(void)
{
static int ledstate,ledctr;
#GLOBAL_INIT{state=0; ledctr=0;};
ledctr-=5; // we run every 5ms
if (ledcttr>0)
return;
ledstate=!ledstate;

digOut (ch1, ledstate); // LED1 off
digOut (ch2, !ledstate); // LED2 on

}

--
------------------------------------------
| Scott G. Henion| s...@shdesigns.org |
| Consultant | Stone Mountain, GA |
| SHDesigns http://www.shdesigns.org |
------------------------------------------

today's fortune
We are all aware that the senses can be deceived, the eyes fooled.
But how can we be sure our senses are not being deceived at any
particular time, or even all the time? Might I just be a brain in
a tank somewhere, tricked all my life into believing in the events
of this world by some insane computer? And does my life gain or lose
meaning based on my reaction to such solipsism?

-- Project PYRRHO, Specimen 46, Vat 7
Activity Recorded M.Y. 2302.22467
TERMINATION OF SPECIMEN ADVISED

------------------------------------



(You need to be a member of rabbit-semi -- send a blank email to rabbit-semi-subscribe@yahoogroups.com )

Hi Scott,

Much thanks. I've been looking at your TimerB already. With a 5 msec interrupt the granularity would be much too coarse for my needs. (The half period would be 5 or 10 or 15 msec.) I need an output selectable by the user at one Hz intervals from 1 to 35 Hz. I'll look at clocking it at a higher rate.

My background is not with embedded systems. But with counter/timer chips like the AMD 9513 or the Intel 8254. Which come with dozens (and dozens) of pages of documentation. I think I just expected to find a timer I could preset with a count (say 1400) and count down at (say) 1 MHz . . . At overflow, grab the interrupt and configure it to reload and preset again . . .

The OP7200 specs say it has "Five 8-bit timers (4 cascadable from the first) and one 10-bit timer with 2 match registers" which pretty much led me to think that Rabbit actually would make it easy to use this hardware. And this bit would be a breeze. With libraries and all that good stuff. Shucks, in the OP7200 manual index there is not even an entry for "clock" or "timer" . . .

Thanks for all you are doing in this area. And all the support you obviously give others.

regards

bob moore

________________________________

From: r...@yahoogroups.com on behalf of Scott Henion
Sent: Tue 5/12/2009 2:32 PM
To: r...@yahoogroups.com
Subject: Re: [rabbit-semi] I need some help to make a part of a largish program pre-emptive

rmoore007ri wrote:
> This is a realtime data collection problem. Running on an OP7200. It drives an optical system and an observer pushes some buttons to change what they see. (or report what they see.)
>
> Part of what they see is two LEDs alternating with each other in square wave fashion at a rate from 5 to 35 Hz. So the half-period is from 14.3 msec to 100 msec.
>
> That part is in a simple costate:
>
> costate flickerout always_on // create flicker here
> {
> waitfor(DelayMs(halfperiod));
> digOut (ch1, 0); // LED1 off
> digOut (ch2, 1); // LED2 on
> waitfor(DelayMs(halfperiod));
> digOut (ch1, 1); // LED1 on
> digOut (ch2, 0); // LED2 off
> }
>
> Of course, early on, before the code got from 2 KB to 88 KB, there was NO perceptible "jiggle" as the observer pressed various pushbuttons tied to digital inputs. But now there are clear blips in this otherwise very clean looking signal.
>
> I've been doing a lot of reading. It looks like I need to make this part of the code run pre-emtively. The need is for this:
>
> - a square wave running from 5 to 35 Hz.
> - the half-period needs to be set from outside the pre-emtive code.
>
> I am having trouble getting my head around this. The SLICE statement looked like the way to go until I realized that it seems to gain control and prevent other things from happening. Of course I get the uneasy feeling that I there is something I just do not see.
>
> I'd appreciate ideas. Anyone want a little work ??
>
> thanks
>
> bob moore
>

Make it run from an interrupt at 5ms. You can use timer B to generate
the int, I have the lib in my free libs page:

http://shdesigns.org/rabbit/freelibs.shtml

halfperiod would be the # of ms, 100 for 5hz, 15 for 35hz (approx)

void TimerBroutine(void)
{
static int ledstate,ledctr;
#GLOBAL_INIT{state=0; ledctr=0;};
ledctr-=5; // we run every 5ms
if (ledcttr>0)
return;
ledstate=!ledstate;

digOut (ch1, ledstate); // LED1 off
digOut (ch2, !ledstate); // LED2 on

}

--
------------------------------------------
| Scott G. Henion| s...@shdesigns.org |
| Consultant | Stone Mountain, GA |
| SHDesigns http://www.shdesigns.org |
------------------------------------------

today's fortune
We are all aware that the senses can be deceived, the eyes fooled.
But how can we be sure our senses are not being deceived at any
particular time, or even all the time? Might I just be a brain in
a tank somewhere, tricked all my life into believing in the events
of this world by some insane computer? And does my life gain or lose
meaning based on my reaction to such solipsism?

-- Project PYRRHO, Specimen 46, Vat 7
Activity Recorded M.Y. 2302.22467
TERMINATION OF SPECIMEN ADVISED

------------------------------------



(You need to be a member of rabbit-semi -- send a blank email to rabbit-semi-subscribe@yahoogroups.com )

You probably won't find this in the OP7200 manual. Rabbit has a lot of manuals, and one of the problems is figuring out which one to consult. My suggestion is to search BOTH the DC manual and the microprocessor manual for more info. I believe that there is also a timerb demo in the samples folder which might be good for a simple how-to demo. And there might also be a tech note or white paper regarding this. I am away from my work computer, so I can't look myself.

I'm running a timer interrupt in the 1k-10k / second range with no problem; it happens exactly as intended. Setting it up is similar to what you describe, except I think that there is both a divisor and a counter to get a wider range of period. Your interrupt can add a third (int or long) counter to reset to various values to get the final long period event.

This is soooo much better than the co-state; the times will be very consistent. Co-state is handy if you are doing a couple simple somethings that are not very time-critical.

Enjy and let us know how it works out for you.

Jon

--- In r...@yahoogroups.com, "Moore, Robert" wrote:
>
> Hi Scott,
>
> Much thanks. I've been looking at your TimerB already. With a 5 msec interrupt the granularity would be much too coarse for my needs. (The half period would be 5 or 10 or 15 msec.) I need an output selectable by the user at one Hz intervals from 1 to 35 Hz. I'll look at clocking it at a higher rate.
>
> My background is not with embedded systems. But with counter/timer chips like the AMD 9513 or the Intel 8254. Which come with dozens (and dozens) of pages of documentation. I think I just expected to find a timer I could preset with a count (say 1400) and count down at (say) 1 MHz . . . At overflow, grab the interrupt and configure it to reload and preset again . . .
>
> The OP7200 specs say it has "Five 8-bit timers (4 cascadable from the first) and one 10-bit timer with 2 match registers" which pretty much led me to think that Rabbit actually would make it easy to use this hardware. And this bit would be a breeze. With libraries and all that good stuff. Shucks, in the OP7200 manual index there is not even an entry for "clock" or "timer" . . .
>
> Thanks for all you are doing in this area. And all the support you obviously give others.
>
> regards
>
> bob moore
>
>
>
> ________________________________
>
> From: r...@yahoogroups.com on behalf of Scott Henion
> Sent: Tue 5/12/2009 2:32 PM
> To: r...@yahoogroups.com
> Subject: Re: [rabbit-semi] I need some help to make a part of a largish program pre-emptive
>
> rmoore007ri wrote:
> > This is a realtime data collection problem. Running on an OP7200. It drives an optical system and an observer pushes some buttons to change what they see. (or report what they see.)
> >
> > Part of what they see is two LEDs alternating with each other in square wave fashion at a rate from 5 to 35 Hz. So the half-period is from 14.3 msec to 100 msec.
> >
> > That part is in a simple costate:
> >
> > costate flickerout always_on // create flicker here
> > {
> > waitfor(DelayMs(halfperiod));
> > digOut (ch1, 0); // LED1 off
> > digOut (ch2, 1); // LED2 on
> > waitfor(DelayMs(halfperiod));
> > digOut (ch1, 1); // LED1 on
> > digOut (ch2, 0); // LED2 off
> > }
> >
> > Of course, early on, before the code got from 2 KB to 88 KB, there was NO perceptible "jiggle" as the observer pressed various pushbuttons tied to digital inputs. But now there are clear blips in this otherwise very clean looking signal.
> >
> > I've been doing a lot of reading. It looks like I need to make this part of the code run pre-emtively. The need is for this:
> >
> > - a square wave running from 5 to 35 Hz.
> > - the half-period needs to be set from outside the pre-emtive code.
> >
> > I am having trouble getting my head around this. The SLICE statement looked like the way to go until I realized that it seems to gain control and prevent other things from happening. Of course I get the uneasy feeling that I there is something I just do not see.
> >
> > I'd appreciate ideas. Anyone want a little work ??
> >
> > thanks
> >
> > bob moore
> >
>
> Make it run from an interrupt at 5ms. You can use timer B to generate
> the int, I have the lib in my free libs page:
>
> http://shdesigns.org/rabbit/freelibs.shtml
>
> halfperiod would be the # of ms, 100 for 5hz, 15 for 35hz (approx)
>
> void TimerBroutine(void)
> {
> static int ledstate,ledctr;
> #GLOBAL_INIT{state=0; ledctr=0;};
> ledctr-=5; // we run every 5ms
> if (ledcttr>0)
> return;
> ledstate=!ledstate;
>
> digOut (ch1, ledstate); // LED1 off
> digOut (ch2, !ledstate); // LED2 on
>
> }
> --
> ------------------------------------------
> | Scott G. Henion| shenion@... |
> | Consultant | Stone Mountain, GA |
> | SHDesigns http://www.shdesigns.org |
> ------------------------------------------
>
> today's fortune
> We are all aware that the senses can be deceived, the eyes fooled.
> But how can we be sure our senses are not being deceived at any
> particular time, or even all the time? Might I just be a brain in
> a tank somewhere, tricked all my life into believing in the events
> of this world by some insane computer? And does my life gain or lose
> meaning based on my reaction to such solipsism?
>
> -- Project PYRRHO, Specimen 46, Vat 7
> Activity Recorded M.Y. 2302.22467
> TERMINATION OF SPECIMEN ADVISED
>
> ------------------------------------



(You need to be a member of rabbit-semi -- send a blank email to rabbit-semi-subscribe@yahoogroups.com )

thanks Jon

could we correspond off-list about his topic.

thanks

bob moore
R...@brown.edu

________________________________

From: r...@yahoogroups.com on behalf of Jon
Sent: Fri 5/15/2009 8:01 AM
To: r...@yahoogroups.com
Subject: [rabbit-semi] Re: I need some help to make a part of a largish program pre-emptive

You probably won't find this in the OP7200 manual. Rabbit has a lot of manuals, and one of the problems is figuring out which one to consult. My suggestion is to search BOTH the DC manual and the microprocessor manual for more info. I believe that there is also a timerb demo in the samples folder which might be good for a simple how-to demo. And there might also be a tech note or white paper regarding this. I am away from my work computer, so I can't look myself.

I'm running a timer interrupt in the 1k-10k / second range with no problem; it happens exactly as intended. Setting it up is similar to what you describe, except I think that there is both a divisor and a counter to get a wider range of period. Your interrupt can add a third (int or long) counter to reset to various values to get the final long period event.

This is soooo much better than the co-state; the times will be very consistent. Co-state is handy if you are doing a couple simple somethings that are not very time-critical.

Enjy and let us know how it works out for you.

Jon

--- In r...@yahoogroups.com, "Moore, Robert" wrote:
>
> Hi Scott,
>
> Much thanks. I've been looking at your TimerB already. With a 5 msec interrupt the granularity would be much too coarse for my needs. (The half period would be 5 or 10 or 15 msec.) I need an output selectable by the user at one Hz intervals from 1 to 35 Hz. I'll look at clocking it at a higher rate.
>
> My background is not with embedded systems. But with counter/timer chips like the AMD 9513 or the Intel 8254. Which come with dozens (and dozens) of pages of documentation. I think I just expected to find a timer I could preset with a count (say 1400) and count down at (say) 1 MHz . . . At overflow, grab the interrupt and configure it to reload and preset again . . .
>
> The OP7200 specs say it has "Five 8-bit timers (4 cascadable from the first) and one 10-bit timer with 2 match registers" which pretty much led me to think that Rabbit actually would make it easy to use this hardware. And this bit would be a breeze. With libraries and all that good stuff. Shucks, in the OP7200 manual index there is not even an entry for "clock" or "timer" . . .
>
> Thanks for all you are doing in this area. And all the support you obviously give others.
>
> regards
>
> bob moore
>
> ________________________________
>
> From: r...@yahoogroups.com on behalf of Scott Henion
> Sent: Tue 5/12/2009 2:32 PM
> To: r...@yahoogroups.com
> Subject: Re: [rabbit-semi] I need some help to make a part of a largish program pre-emptive
>
> rmoore007ri wrote:
> > This is a realtime data collection problem. Running on an OP7200. It drives an optical system and an observer pushes some buttons to change what they see. (or report what they see.)
> >
> > Part of what they see is two LEDs alternating with each other in square wave fashion at a rate from 5 to 35 Hz. So the half-period is from 14.3 msec to 100 msec.
> >
> > That part is in a simple costate:
> >
> > costate flickerout always_on // create flicker here
> > {
> > waitfor(DelayMs(halfperiod));
> > digOut (ch1, 0); // LED1 off
> > digOut (ch2, 1); // LED2 on
> > waitfor(DelayMs(halfperiod));
> > digOut (ch1, 1); // LED1 on
> > digOut (ch2, 0); // LED2 off
> > }
> >
> > Of course, early on, before the code got from 2 KB to 88 KB, there was NO perceptible "jiggle" as the observer pressed various pushbuttons tied to digital inputs. But now there are clear blips in this otherwise very clean looking signal.
> >
> > I've been doing a lot of reading. It looks like I need to make this part of the code run pre-emtively. The need is for this:
> >
> > - a square wave running from 5 to 35 Hz.
> > - the half-period needs to be set from outside the pre-emtive code.
> >
> > I am having trouble getting my head around this. The SLICE statement looked like the way to go until I realized that it seems to gain control and prevent other things from happening. Of course I get the uneasy feeling that I there is something I just do not see.
> >
> > I'd appreciate ideas. Anyone want a little work ??
> >
> > thanks
> >
> > bob moore
> > Make it run from an interrupt at 5ms. You can use timer B to generate
> the int, I have the lib in my free libs page:
>
> http://shdesigns.org/rabbit/freelibs.shtml
>
> halfperiod would be the # of ms, 100 for 5hz, 15 for 35hz (approx)
>
> void TimerBroutine(void)
> {
> static int ledstate,ledctr;
> #GLOBAL_INIT{state=0; ledctr=0;};
> ledctr-=5; // we run every 5ms
> if (ledcttr>0)
> return;
> ledstate=!ledstate;
>
> digOut (ch1, ledstate); // LED1 off
> digOut (ch2, !ledstate); // LED2 on
>
> }
> --
> ------------------------------------------
> | Scott G. Henion| shenion@... |
> | Consultant | Stone Mountain, GA |
> | SHDesigns http://www.shdesigns.org |
> ------------------------------------------
>
> today's fortune
> We are all aware that the senses can be deceived, the eyes fooled.
> But how can we be sure our senses are not being deceived at any
> particular time, or even all the time? Might I just be a brain in
> a tank somewhere, tricked all my life into believing in the events
> of this world by some insane computer? And does my life gain or lose
> meaning based on my reaction to such solipsism?
>
> -- Project PYRRHO, Specimen 46, Vat 7
> Activity Recorded M.Y. 2302.22467
> TERMINATION OF SPECIMEN ADVISED
>
> ------------------------------------


(You need to be a member of rabbit-semi -- send a blank email to rabbit-semi-subscribe@yahoogroups.com )

Hi All,

My need was for a low frequency square wave from 5 to 35 Hz that would be rock stable despite a lot of other activity from digital inputs (from user pushbuttons) and a slew of DAC outputs changing at the other end of rabbitnet. The target is Rabbit's OP7200 . . .

Scott Henion's timerB implementation did the trick. Here is a simple (but complete) example that steps through the frequencies. It might help some newebies.

timerB available at
http://shdesigns.org/rabbit/freelibs.shtml

regards

bob moore

__________________________________________________________
#memmap xmem // reduce root mem
#class auto //
#use "timerb.lib" // Steve Henion timerB library
//#define TIMER_INT_ENA // permits other interrupts if timerB is running
// (may be needed in your application)
#define DIGOUTCONFIG 0xF0 // needed for OP7200 digital output channels

nodebug void msDelay(unsigned int delay)
{
unsigned long done_time;
done_time = MS_TIMER + delay;
while( (long) (MS_TIMER - done_time) < 0 );
}

nodebug root void TimerBRoutine(void)
{
static int ledstate;
static int ch0, ch1;
#GLOBAL_INIT{ch0 = 0; ch1 = 1; ledstate = 0;};
ledstate=!ledstate;
digOut (ch0, ledstate); // ch1 off/on
digOut (ch1, !ledstate); // ch2 on/off
}
#nodebug
main()
{
unsigned long halfperiod;
int lofrate;
int intpriority; // from 1 lowest to 3 highest
intpriority = 1; // MUST be "1" in MY target app
brdInit();
digOutConfig(DIGOUTCONFIG); // configure digital outputs . . .
while (1)
{
for (lofrate = 5; lofrate < 36; lofrate++) // rates from 5 - 35 Hz
{
halfperiod = 500000/lofrate; // in usec
TimerBUninit(); // unitialize before reinitializing
TimerBInit(halfperiod, intpriority); // at a new rate
printf("low frequency rate = %02d\n",lofrate);
msDelay(3000);
} // end for
} // end while
} // end main
____________________________________________________________________
------------------------------------



(You need to be a member of rabbit-semi -- send a blank email to rabbit-semi-subscribe@yahoogroups.com )

The off-line thing didn't seem to work out. Perhaps a new thread is in order. But I found the best was to dig around through the books and tinker for several days. Let me know how worked out for you.

Jon

--- In r...@yahoogroups.com, "Moore, Robert" wrote:
>
> thanks Jon
>
> could we correspond off-list about his topic.
>
> thanks
>
> bob moore
> Robert_Moore@...
>
> ________________________________
>
> From: r...@yahoogroups.com on behalf of Jon
> Sent: Fri 5/15/2009 8:01 AM
> To: r...@yahoogroups.com
> Subject: [rabbit-semi] Re: I need some help to make a part of a largish program pre-emptive
>
> You probably won't find this in the OP7200 manual. Rabbit has a lot of manuals, and one of the problems is figuring out which one to consult. My suggestion is to search BOTH the DC manual and the microprocessor manual for more info. I believe that there is also a timerb demo in the samples folder which might be good for a simple how-to demo. And there might also be a tech note or white paper regarding this. I am away from my work computer, so I can't look myself.
>
> I'm running a timer interrupt in the 1k-10k / second range with no problem; it happens exactly as intended. Setting it up is similar to what you describe, except I think that there is both a divisor and a counter to get a wider range of period. Your interrupt can add a third (int or long) counter to reset to various values to get the final long period event.
>
> This is soooo much better than the co-state; the times will be very consistent. Co-state is handy if you are doing a couple simple somethings that are not very time-critical.
>
> Enjy and let us know how it works out for you.
>
> Jon
>
> --- In r...@yahoogroups.com, "Moore, Robert" wrote:
> >
> > Hi Scott,
> >
> > Much thanks. I've been looking at your TimerB already. With a 5 msec interrupt the granularity would be much too coarse for my needs. (The half period would be 5 or 10 or 15 msec.) I need an output selectable by the user at one Hz intervals from 1 to 35 Hz. I'll look at clocking it at a higher rate.
> >
> > My background is not with embedded systems. But with counter/timer chips like the AMD 9513 or the Intel 8254. Which come with dozens (and dozens) of pages of documentation. I think I just expected to find a timer I could preset with a count (say 1400) and count down at (say) 1 MHz . . . At overflow, grab the interrupt and configure it to reload and preset again . . .
> >
> > The OP7200 specs say it has "Five 8-bit timers (4 cascadable from the first) and one 10-bit timer with 2 match registers" which pretty much led me to think that Rabbit actually would make it easy to use this hardware. And this bit would be a breeze. With libraries and all that good stuff. Shucks, in the OP7200 manual index there is not even an entry for "clock" or "timer" . . .
> >
> > Thanks for all you are doing in this area. And all the support you obviously give others.
> >
> > regards
> >
> > bob moore
> >
> >
> >
> > ________________________________
> >
> > From: r...@yahoogroups.com on behalf of Scott Henion
> > Sent: Tue 5/12/2009 2:32 PM
> > To: r...@yahoogroups.com
> > Subject: Re: [rabbit-semi] I need some help to make a part of a largish program pre-emptive
> >
> >
> >
> > rmoore007ri wrote:
> > > This is a realtime data collection problem. Running on an OP7200. It drives an optical system and an observer pushes some buttons to change what they see. (or report what they see.)
> > >
> > > Part of what they see is two LEDs alternating with each other in square wave fashion at a rate from 5 to 35 Hz. So the half-period is from 14.3 msec to 100 msec.
> > >
> > > That part is in a simple costate:
> > >
> > > costate flickerout always_on // create flicker here
> > > {
> > > waitfor(DelayMs(halfperiod));
> > > digOut (ch1, 0); // LED1 off
> > > digOut (ch2, 1); // LED2 on
> > > waitfor(DelayMs(halfperiod));
> > > digOut (ch1, 1); // LED1 on
> > > digOut (ch2, 0); // LED2 off
> > > }
> > >
> > > Of course, early on, before the code got from 2 KB to 88 KB, there was NO perceptible "jiggle" as the observer pressed various pushbuttons tied to digital inputs. But now there are clear blips in this otherwise very clean looking signal.
> > >
> > > I've been doing a lot of reading. It looks like I need to make this part of the code run pre-emtively. The need is for this:
> > >
> > > - a square wave running from 5 to 35 Hz.
> > > - the half-period needs to be set from outside the pre-emtive code.
> > >
> > > I am having trouble getting my head around this. The SLICE statement looked like the way to go until I realized that it seems to gain control and prevent other things from happening. Of course I get the uneasy feeling that I there is something I just do not see.
> > >
> > > I'd appreciate ideas. Anyone want a little work ??
> > >
> > > thanks
> > >
> > > bob moore
> > >
> >
> > Make it run from an interrupt at 5ms. You can use timer B to generate
> > the int, I have the lib in my free libs page:
> >
> > http://shdesigns.org/rabbit/freelibs.shtml
> >
> > halfperiod would be the # of ms, 100 for 5hz, 15 for 35hz (approx)
> >
> > void TimerBroutine(void)
> > {
> > static int ledstate,ledctr;
> > #GLOBAL_INIT{state=0; ledctr=0;};
> > ledctr-=5; // we run every 5ms
> > if (ledcttr>0)
> > return;
> > ledstate=!ledstate;
> >
> > digOut (ch1, ledstate); // LED1 off
> > digOut (ch2, !ledstate); // LED2 on
> >
> > }
> >
> >
> >
> >
> >
> >
> > --
> > ------------------------------------------
> > | Scott G. Henion| shenion@ |
> > | Consultant | Stone Mountain, GA |
> > | SHDesigns http://www.shdesigns.org |
> > ------------------------------------------
> >
> > today's fortune
> > We are all aware that the senses can be deceived, the eyes fooled.
> > But how can we be sure our senses are not being deceived at any
> > particular time, or even all the time? Might I just be a brain in
> > a tank somewhere, tricked all my life into believing in the events
> > of this world by some insane computer? And does my life gain or lose
> > meaning based on my reaction to such solipsism?
> >
> > -- Project PYRRHO, Specimen 46, Vat 7
> > Activity Recorded M.Y. 2302.22467
> > TERMINATION OF SPECIMEN ADVISED
> >
> >
> >
> > ------------------------------------
> >
> >



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