bladerf: implement options for clock configuration

Since firmware 2016.01-rc1 bladeRF has the ability to lock to an
external reference as well as produce arbitrary frequency signal
(25 MHz here) on its clock output.

Use gr-osmosdr source with the following arguments to produce 25
MHz on the SMB connector:

osmocom_fft -a bladerf,smb=25e6

smb=25e6

To lock the bladeRF itself to an external GPSDO reference, use
additional arguments tamer=external for 10MHz or tamer=external_1pps for
1PPS GPSDO signals.

osmocom_fft -a bladerf,smb=25e6,tamer=external

tamer={internal,external_1pps,external}

The described method requires https://github.com/Nuand/bladeRF/releases/
tag/2016.01-rc1

Carefully *read the instructions for external reference locking*
(especially max allowed voltage levels) on Nuand's blog https://
www.nuand.com/blog/2016-01-rc1-release/

1 files changed, 4 insertions, 0 deletions

diff --git a/lib/bladerf/bladerf_sink_c.h b/lib/bladerf/bladerf_sink_c.h
index 57d174b..496abf4 100644
--- a/lib/bladerf/bladerf_sink_c.h
+++ b/lib/bladerf/bladerf_sink_c.h
@@ -117,6 +117,10 @@ public:
   double set_bandwidth( double bandwidth, size_t chan = 0 );
   double get_bandwidth( size_t chan = 0 );
   osmosdr::freq_range_t get_bandwidth_range( size_t chan = 0 );
+
+  void set_clock_source(const std::string &source, const size_t mboard = 0);
+  std::string get_clock_source(const size_t mboard);
+  std::vector<std::string> get_clock_sources(const size_t mboard);
 };
 
 #endif /* INCLUDED_BLADERF_SINK_C_H */