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I am currently study someone’s code for detecting the pressing of the button of the STK board!!!

if ( keys & 1 )

led = 1;

else if ( keys & 2 ) // priority encoder: if multiple switches are pressed,

led = 2; // only the lowest switch is recognized

else if ( keys & 4 )

led = 4;

else if ( keys & 8 )

led = 8;

else if ( keys & 0x10 )

led = 0x10;

else if ( keys & 0x20 )

led = 0x20;

else if ( keys & 0x40 )

led = 0x40;

else if ( keys & 0x80 )

led = 0x80;

Can someone explain to me why the keys is compared by using 2, 4, 8, 0x10, 0x20, 0x40, 0x80!!! And is there other way of detecting it?

Thanks

Steven

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Steven Chang-Lin Yu
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