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Ports

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nbalderaz

Programmer
Sep 25, 2005
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Hello

Can somebody tell me how to set only specific pins in a port to be output. I dont want to use all of them just specific ones. I have found code to make all the pins output:

STA DDRA ;Make Port A all outputs

but i just want certain pins to be output
 
What processor are you using?

With most processors, the data direction register will set a bit as output with the corresponding bit the DDR low (say) and as an input with the bit high (say).

So if the DDR has 8 bits and you wanted bit 2 as an output and the rest as inputs you would write 11111011 to the DDR.

If you wanted bit 1 and bit 6 as outputs then you'd write 10111101 to the DDR and so on.

In other words, it all depends on the bit pattern that you write to the DDR.
 
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