ttsou/openbts-uhd — comment on commit fda11abe6c3e58b80eac422dbcda3c1f55a6dbcc
File:  line 0
By ttsou:

Hi Erik,

Normal email is preferred way to reach me. Github mangles email
addresses, which confuses my message filters.

On Fri, Nov 11, 2011 at 7:55 PM, Erik Johnson

wrote:
> This might not be the place to ask this question at all...I came across a thread you were responding to with regards to a clock rate error ie: "TRX clock interface timed out"). I checked the log files the TRX Manager log files and found that the following error was the culprit ( or at least I think) : "UHDDevice.cpp:333:set_rates: Failed to set master clock rate".

What type of device? That matters a lot.

Whether the master clock should be set at all depends on the type
device. The USRP1 doesn't use the UHD driver, so it is a separate
case. Only on B100 and E100 devices can the clock rate be set to 52
MHz. USRP2 and N2xx run at 100 MHz and this value can't be changed (to
a useful value); for that reason, those devices need host-based sample
rate conversion specified at configure time.

./configure --with-resamp

Yes, the wiki is out-of-date and this mandatory option is not well documented.

In short, the UHD clock rate should _only_ be set on B100 or E100. For
USRP2 derived devices, the default is the only option, so the clock
rate setting is never called. And again, the USRP1 is a separate
issue.

> Now that I see the code here, I can deduce that the clock rate is not being set on the device. I'm able to ping it just fine using uhd_usrp_probe, as well as I think I'm running the latest firmware. I was hoping you could provide some insight if you knew why this might be happening?

So depending on the type of device, do you need to set the master clock rate?

Thomas