# UART pins

**URL:** <https://forums.sifive.com/t/uart-pins/1501>\
**Category:** HiFive1 Rev B\
**Created:** [August 13, 2018, 5:03am UTC](https://forums.sifive.com/t/uart-pins/1501 "2018-08-13T05:03:02Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![daniel](https://avatars.discourse-cdn.com/v4/letter/d/3ec8ea/32.png) [@daniel](https://forums.sifive.com/u/daniel)\
**Post date:** [August 13, 2018, 5:03am UTC](https://forums.sifive.com/t/uart-pins/1501/1 "2018-08-13T05:03:02Z")

</div>

#define IOF\_UART0\_RX (16u)  
#define IOF\_UART0\_TX (17u)

how to use this ?

what is the difference between

IOF\_SEL of PIN 0 and PIN 1 (selecting uart function)  
IOF\_EN of PIN 0 and PIN 1 (enabling)

and

the macro  
#define IOF\_UART0\_RX (16u)  
#define IOF\_UART0\_TX (17u)

??