# External clock for hdlc application

**URL:** <https://forums.digi.com/t/external-clock-for-hdlc-application/3490>\
**Category:** NET+OS\
**Tags:** hardware\
**Created:** [June 22, 2005, 3:24pm UTC](https://forums.digi.com/t/external-clock-for-hdlc-application/3490 "2005-06-22T15:24:49Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![netfuzz](https://avatars.discourse-cdn.com/v4/letter/n/c0e974/32.png) [@netfuzz](https://forums.digi.com/u/netfuzz)\
**Post date:** [June 22, 2005, 3:24pm UTC](https://forums.digi.com/t/external-clock-for-hdlc-application/3490/1 "2005-06-22T15:24:49Z")

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Hi,  
I implemented an Hdlc application on the EM board and I want to use an external clock for TX and Rx.  
I set naHdlcIoctl(channel,NAHDLC\_TX\_CLCK\_EXT,(void\*)TRUE);  
as it is told in the Api and I also connected my external clock physically to RTS/SPI\_CLK pin.  
No transmission is occuring .Do i have some additionnal settings to do ? answer if you have any idea.

Thanks,