[time-nuts] BeagleBone Black NTP server

Iain Young iain at g7iii.net
Sat May 10 07:57:56 UTC 2014

On 10/05/14 04:38, nuts wrote:

> Note a bug on the BBB is if you use a cape, it blocks the connector to
> the serial port.

"The" serial port ? I assume you mean the UART0, aka the console ?
There are 5 others to choose from (UART3 doesn't have all the pins
brought out from the but makes a great PPS or MSF/DCF input)

Those 5 are brought out to P8 and/or P9. You may have to twiddle some
pinmux, and lose access to the HDMI and onboard MMC, depending on which
port you choose, but you can stilll use the SD card slot. Why would you
want HDMI on an NTP server anyway ?

These days, you just load the appropriate Cape firmware (Yes, even if
you don't actually haver a serial cape, the firmware essentially
twiddles those pinmux's for you.

Now, the BBB has a better PPS input. The TIMER4-TIMER7 inputs can be
used, *IF* you are willing to run FreeBSD rather than Linux. See:


(Note, no need for patches now, just grab the snapshots from 
ftp.freebsd.org. the patch is in there) I _think_ it's also in the
latest releases, I'd need to check to be sure though.

I know there was some work done on a similiar facitility for Linux, but
not sure if the Author has had the time to finish the work.

I have my BBBs fed from my Austrons via a 5V->3.3V voltage divider. One
thing I'd like to try is feeding the BBB the 10MHz clock from the
Austrons, as it also has an External Clock Input Pin (TCLKIN), but that
will need some kernel work to select the external clock. It may also
need further work in uboot.

Treat the BBB and Pi just like any other Linux box :)


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