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ViperARG
Joined: 07 Jan 2017
Posts: 16
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| Bitwise operators HELP |
 Posted: Mon Jan 30, 2017 10:55 am |
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Hi guys, I'm the noob again haha ^^.
I'm still learning C code and PICs, and I always used to switch pins like this PORTBbits.RB0 = 1; for example to do a simple LED chaser, but I saw "<< >> " to move bits right and left and I wanted to build an LED chaser from RB0 to RB7 using this bitwise operator, can I get an example please ? |
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newguy
Joined: 24 Jun 2004
Posts: 1904
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| Posted: Mon Jan 30, 2017 11:21 am |
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| Code: | unsigned int8 pattern = 0x80;
pattern >>= 1; // pattern now holds 0x40
pattern >>= 2; // pattern now holds 0x10
pattern <<= 1; // pattern now holds 0x20 |
I'm leaving it up to you to determine:
a) how to write directly to an entire port at once;
b) how to create your LED chaser. In general, it will have to consist of a shift section (you'll need to keep track of whether you're traveling L or R, and perform the appropriate shift), and a delay section. These two steps will repeat forever. |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19436
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| Posted: Mon Jan 30, 2017 11:54 am |
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Also, as a further comment, >> & << are the generic 'C' shifts. However for a rotation, you might want to look at the rotate_right and rotate_left functions:
| Code: |
int8 val=0b00000001;
rotate_left(&val,1); //gives 0b00000010
rotate_right(&val,1); //back to the start
rotate_right(&val,1); //gives 0b10000000
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Unlike the shift, where the bit would disappear 'out the bottom', the bit rotates back round to the top of the variable. |
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ViperARG
Joined: 07 Jan 2017
Posts: 16
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| Posted: Wed Feb 01, 2017 12:03 pm |
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| Ttelmah wrote: | Also, as a further comment, >> & << are the generic 'C' shifts. However for a rotation, you might want to look at the rotate_right and rotate_left functions:
| Code: |
int8 val=0b00000001;
rotate_left(&val,1); //gives 0b00000010
rotate_right(&val,1); //back to the start
rotate_right(&val,1); //gives 0b10000000
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Unlike the shift, where the bit would disappear 'out the bottom', the bit rotates back round to the top of the variable. |
Awesome thanks, I didn´t know that. I think that one is more suitable for what I want to do ^^ |
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