diff options
Diffstat (limited to 'host/lib/usrp/common/lmx2592.cpp')
| -rw-r--r-- | host/lib/usrp/common/lmx2592.cpp | 49 |
1 files changed, 43 insertions, 6 deletions
diff --git a/host/lib/usrp/common/lmx2592.cpp b/host/lib/usrp/common/lmx2592.cpp index 0833bc7c4..0a409f117 100644 --- a/host/lib/usrp/common/lmx2592.cpp +++ b/host/lib/usrp/common/lmx2592.cpp @@ -235,6 +235,8 @@ public: pfd_freq = input_freq / _regs.pll_r; } + _set_fcal_adj_values(pfd_freq); + // Calculate N and frac const auto N_dot_F = target_vco_freq / (pfd_freq * prescaler); auto N = static_cast<uint16_t>(std::floor(N_dot_F)); @@ -253,12 +255,12 @@ public: // Calculate Fnum const auto initial_fnum = static_cast<uint32_t>(std::round(frac * fden)); const auto fnum = (spur_dodging) ? _find_fnum(N, - initial_fnum, - fden, - prescaler, - pfd_freq, - output_divider, - spur_dodging_threshold) + initial_fnum, + fden, + prescaler, + pfd_freq, + output_divider, + spur_dodging_threshold) : initial_fnum; // Calculate mash_seed @@ -519,6 +521,41 @@ private: // Members } } + void _set_fcal_adj_values(const double pfd_freq) + { + // Adjust FCAL speed for particularly high or low PFD frequencies + if (pfd_freq < 5e6) { + _regs.fcal_lpfd_adj = lmx2592_regs_t::fcal_lpfd_adj_t::FCAL_LPFD_ADJ_5MHZ; + _regs.fcal_hpfd_adj = lmx2592_regs_t::fcal_hpfd_adj_t::FCAL_HPFD_ADJ_UNUSED; + _regs.pfd_ctl = lmx2592_regs_t::pfd_ctl_t::PFD_CTL_DUAL_PFD; + } else if (pfd_freq < 10e6) { + _regs.fcal_lpfd_adj = lmx2592_regs_t::fcal_lpfd_adj_t::FCAL_LPFD_ADJ_10MHZ; + _regs.fcal_hpfd_adj = lmx2592_regs_t::fcal_hpfd_adj_t::FCAL_HPFD_ADJ_UNUSED; + _regs.pfd_ctl = lmx2592_regs_t::pfd_ctl_t::PFD_CTL_DUAL_PFD; + } else if (pfd_freq < 20e6) { + _regs.fcal_lpfd_adj = lmx2592_regs_t::fcal_lpfd_adj_t::FCAL_LPFD_ADJ_20MHZ; + _regs.fcal_hpfd_adj = lmx2592_regs_t::fcal_hpfd_adj_t::FCAL_HPFD_ADJ_UNUSED; + _regs.pfd_ctl = lmx2592_regs_t::pfd_ctl_t::PFD_CTL_DUAL_PFD; + } else if (pfd_freq <= 100e6) { + _regs.fcal_lpfd_adj = lmx2592_regs_t::fcal_lpfd_adj_t::FCAL_LPFD_ADJ_UNUSED; + _regs.fcal_hpfd_adj = lmx2592_regs_t::fcal_hpfd_adj_t::FCAL_HPFD_ADJ_UNUSED; + _regs.pfd_ctl = lmx2592_regs_t::pfd_ctl_t::PFD_CTL_DUAL_PFD; + } else if (pfd_freq <= 150e6) { + _regs.fcal_lpfd_adj = lmx2592_regs_t::fcal_lpfd_adj_t::FCAL_LPFD_ADJ_UNUSED; + _regs.fcal_hpfd_adj = lmx2592_regs_t::fcal_hpfd_adj_t::FCAL_HPFD_ADJ_100MHZ; + _regs.pfd_ctl = lmx2592_regs_t::pfd_ctl_t::PFD_CTL_DUAL_PFD; + } else if (pfd_freq <= 200e6) { + _regs.fcal_lpfd_adj = lmx2592_regs_t::fcal_lpfd_adj_t::FCAL_LPFD_ADJ_UNUSED; + _regs.fcal_hpfd_adj = lmx2592_regs_t::fcal_hpfd_adj_t::FCAL_HPFD_ADJ_150MHZ; + _regs.pfd_ctl = lmx2592_regs_t::pfd_ctl_t::PFD_CTL_DUAL_PFD; + } else { + // Note, this case requires single-loop PFD which increases PLL noise floor + _regs.fcal_lpfd_adj = lmx2592_regs_t::fcal_lpfd_adj_t::FCAL_LPFD_ADJ_UNUSED; + _regs.fcal_hpfd_adj = lmx2592_regs_t::fcal_hpfd_adj_t::FCAL_HPFD_ADJ_200MHZ; + _regs.pfd_ctl = lmx2592_regs_t::pfd_ctl_t::PFD_CTL_SINGLE_PFD; + } + } + // "k" is a derived value that indicates where sub-fractional spurs will be present // at a given Fden value. A "k" value of 1 indicates there will be no spurs. // See the LMX2592 datasheet for more information |