Subject:
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Re: Non-polaroid Sonar
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Thu, 16 Mar 2000 13:42:47 GMT
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Original-From:
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Adam Oliver <oli@wantree.com.auSTOPSPAMMERS>
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Viewed:
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1327 times
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Thanks for your help :-D
Just so I'm clear, ref pink book page 10-17.
Does the "bit_set( 0x1021, 1 );" refer to bit 0 -EDG3B, and
bit_clear( 0x1021, 2 ); " refer to bit 1 -EDG3A.
This is what was throwing me, I always thought bits started at zero and
ended at 7, not 1 to 8 as appears to be the case here. Is this what the
"zero-indexed " means?
sorry if it's a basic question, but if you don't ask you never learn :-)
thanks Again
Adam
> In the sonar code from the web site, the rising edge detection on timer • input channel 3 (TIC3) is set like this:
>
> bit_clear( 0x1021, 2 ); bit_set( 0x1021, 1 );
>
> According to the little pink book, address 0x1021 is the Timer Control
Register 2 (TCTL2) (in the Register & Control Bit Assignments section). To
set channel 3 to capture falling edges only, you'd make the last two bits
(set, clear) instead of (clear, set), like this:
>
> bit_set( 0x1021, 2 ); bit_clear( 0x1021, 1 );
>
> Hope this helps!
>
> -- Will
>
> BTW, can anyone tell me why the bit_set and bit_clear commands aren't
zero-indexed WRT the bit index (like everything else in C and machine code
is)? Just curious.
>
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Message has 1 Reply:
 | | Re: Non-polaroid Sonar
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| (...) No, that's a very good question. It had me confused, too. The second argument to bit_set and bit_clear is not actually the index of a bit at all; it's a bit mask. For example, when you do bit_set( 0x1021, 3 ), the 3 becomes 0000 0011 in (...) (25 years ago, 16-Mar-00, to lugnet.robotics.handyboard)
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Message is in Reply To:
| | Re: Non-polaroid Sonar
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| In the sonar code from the web site, the rising edge detection on timer input channel 3 (TIC3) is set like this: bit_clear( 0x1021, 2 ); bit_set( 0x1021, 1 ); According to the little pink book, address 0x1021 is the Timer Control Register 2 (TCTL2) (...) (25 years ago, 15-Mar-00, to lugnet.robotics.handyboard)
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