Subject:
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Re: your mail
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Fri, 28 Jun 1996 17:47:29 GMT
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Original-From:
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Mike Ross <mross@outland.!AntiSpam!jsc.nasa.gov>
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Viewed:
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3887 times
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On Fri, 28 Jun 1996, System User wrote:
> Jeff Keyser wrote:
> > I'm trying to figure out what the BCLR line does. Why does it clear
> > the bits of all the timers _except_ the one it's using? I would think that
> > BSET TFLG1,X %00000010 would be more appropriate for the task. Anyone know
> > how this works
>
> I found this entry in the HC11 handbook, page 10-14. It may help..
>
> "The most common way of clearing a status flag bit in the timer flag
> registers is to load an accumulator with a mask that has a one in the bit(s)
> corresponding to the flag(s) to be cleared; Then write this value to TFLG1
> or TFLG2. The mask, which is supplied with the BCLR instruction, should
> have zeros in the bit positions corresponding to the flags to be cleared
> and ones in all other bits."
And to add to all the confusion, see page A-15 of the same book, which
contradicts what page 10-14 says. I followed he instructions on page
10-14 and it worked.
Also remember those odd word-blitz methods of clearing a single bit only
seem to work on the TFLG1 and TFLG2 status registers. Otherwise use BSET
and BCLR. My 2 cents only.
HTH,
-mike
* Michael L. Ross/C33 | Lockheed Engineering & Sciences Co.****
* Robotics Department | 2400 Nasa Rd. 1, Houston, TX 77058*****
*(713)333-7094 voice,(713)333-6071 fax*#include <disclaimer.h>*
* Finger me for my public key. mross@outland.jsc.nasa.gov ****
* If you weren't a socialist in your twenties, you had no heart.
* If you weren't a conservative by your thirties, you have no brain.
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