[time-nuts] BeagleBone Black DDMTD update

Simon Marsh subscriptions at burble.com
Wed Oct 29 18:50:53 EDT 2014

On 29/10/2014 22:22, Bob Camp wrote:
> Hi
> It is not at all unusual for signals to be re-clocked when going into a micro. Often the documentation on this process is somewhere between vague and non-exsistant.
> Bob

Yes, luckily the Sitra TRM has a nice clear diagram for the mechanism I 
use and the signals are re-clocked twice on their way in to the BBB 
(@100mhz for the OCP bus then @200mhz for the PRU).

The timing at the BBB is not critical though, the signal is captured in 
the sampler @ 10mhz and the BBB has a shade under 100ns to read it 
before the next sample comes in. In initial testing, I had the BBB 
continuously sampling and had no problems keeping up @10mhz (I actually 
had to slow it down to make it work).



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