[USRP-users] Clock selection between external and GPSDO clocks

Piotr Krysik perper at o2.pl
Fri Apr 17 07:42:27 EDT 2015


Hi all,

N210 has manually switched clock source between "external" and "gpsdo"
with use of the J510 jumper (see 4th page of schematics
http://files.ettus.com/schematics/n200/n2xx.pdf).

I don't know to the full extent what
multi_usrp::set_clock_source("gpsdo") and  set_clock_source("external")
commands do, but on hardware level it seems that they are equivalent.
This is the part usrp2_impl.cpp responsible for setting clock source in
USRP's N210 FPGA register:

case usrp2_iface::USRP_N210_R4:
        if      (source == "internal") 
_mbc[mb].iface->poke32(U2_REG_MISC_CTRL_CLOCK, 0x12);
        else if (source == "external") 
_mbc[mb].iface->poke32(U2_REG_MISC_CTRL_CLOCK, 0x1C);
        else if (source == "gpsdo")    
_mbc[mb].iface->poke32(U2_REG_MISC_CTRL_CLOCK, 0x1C);
        else if (source == "mimo")     
_mbc[mb].iface->poke32(U2_REG_MISC_CTRL_CLOCK, 0x15);

Best Regards,
Piotr Krysik


W dniu 17.04.2015 o 12:20, Marcus Müller via USRP-users pisze:
> Hi Hanwen,
>
> have you tried multi_usrp::set_clock_source("gpsdo") and
> set_clock_source("external") [1]?
> Generally, the N210 should have four possible values:
> * internal (on-board oscillator)
> * external (SMA connector)
> * gpsdo (GPSDO) and
> * mimo
>
> You can query these using get_clock_sources[2].
>
> Greetings,
> Marcus
> [1]
> http://files.ettus.com/manual/classuhd_1_1usrp_1_1multi__usrp.html#a73ed40009d0d3787c183d42423d25026
> [2]
> http://files.ettus.com/manual/classuhd_1_1usrp_1_1multi__usrp.html#a3e1022d151717e49ce69c987bd07b243
>
> On 04/17/2015 07:30 AM, hanwen via USRP-users wrote:
>> Hi,
>>
>> I have some N210 with GPSDO inside. In UHD API, how I can select
>> between external 10MH/1PPS from OctoClockG and the internal clock
>> signals from GPSDO? I didn‘t find any API that I could explicitly
>> switch between the external and the GPSDO clocks.
>>
>>
>> Cheers,
>> Hanwen
>>
>>
>> _______________________________________________
>> USRP-users mailing list
>> USRP-users at lists.ettus.com
>> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
>
>
>
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