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//
// Copyright 2011-2012 Ettus Research LLC
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
//
#include "adf4351_regs.hpp"
#include "db_sbx_common.hpp"
using namespace uhd;
using namespace uhd::usrp;
using namespace boost::assign;
/***********************************************************************
* Structors
**********************************************************************/
sbx_xcvr::sbx_version4::sbx_version4(sbx_xcvr *_self_sbx_xcvr) {
//register the handle to our base SBX class
self_base = _self_sbx_xcvr;
}
sbx_xcvr::sbx_version4::~sbx_version4(void){
/* NOP */
}
/***********************************************************************
* Tuning
**********************************************************************/
double sbx_xcvr::sbx_version4::set_lo_freq(dboard_iface::unit_t unit, double target_freq) {
UHD_LOGV(often) << boost::format(
"SBX tune: target frequency %f Mhz"
) % (target_freq/1e6) << std::endl;
//clip the input
target_freq = sbx_freq_range.clip(target_freq);
//map prescaler setting to mininmum integer divider (N) values (pg.18 prescaler)
static const uhd::dict<int, int> prescaler_to_min_int_div = map_list_of
(0,23) //adf4351_regs_t::PRESCALER_4_5
(1,75) //adf4351_regs_t::PRESCALER_8_9
;
//map rf divider select output dividers to enums
static const uhd::dict<int, adf4351_regs_t::rf_divider_select_t> rfdivsel_to_enum = map_list_of
(1, adf4351_regs_t::RF_DIVIDER_SELECT_DIV1)
(2, adf4351_regs_t::RF_DIVIDER_SELECT_DIV2)
(4, adf4351_regs_t::RF_DIVIDER_SELECT_DIV4)
(8, adf4351_regs_t::RF_DIVIDER_SELECT_DIV8)
(16, adf4351_regs_t::RF_DIVIDER_SELECT_DIV16)
(32, adf4351_regs_t::RF_DIVIDER_SELECT_DIV32)
(64, adf4351_regs_t::RF_DIVIDER_SELECT_DIV64)
;
double actual_freq, pfd_freq;
double ref_freq = self_base->get_iface()->get_clock_rate(unit);
int R=0, BS=0, N=0, FRAC=0, MOD=0;
int RFdiv = 1;
adf4351_regs_t::reference_divide_by_2_t T = adf4351_regs_t::REFERENCE_DIVIDE_BY_2_DISABLED;
adf4351_regs_t::reference_doubler_t D = adf4351_regs_t::REFERENCE_DOUBLER_DISABLED;
//Reference doubler for 50% duty cycle
// if ref_freq < 12.5MHz enable regs.reference_divide_by_2
if(ref_freq <= 12.5e6) D = adf4351_regs_t::REFERENCE_DOUBLER_ENABLED;
//increase RF divider until acceptable VCO frequency
double vco_freq = target_freq;
while (vco_freq < 2.2e9) {
vco_freq *= 2;
RFdiv *= 2;
}
//use 8/9 prescaler for vco_freq > 3 GHz (pg.18 prescaler)
adf4351_regs_t::prescaler_t prescaler = target_freq > 3e9 ? adf4351_regs_t::PRESCALER_8_9 : adf4351_regs_t::PRESCALER_4_5;
/*
* The goal here is to loop though possible R dividers,
* band select clock dividers, N (int) dividers, and FRAC
* (frac) dividers.
*
* Calculate the N and F dividers for each set of values.
* The loop exits when it meets all of the constraints.
* The resulting loop values are loaded into the registers.
*
* from pg.21
*
* f_pfd = f_ref*(1+D)/(R*(1+T))
* f_vco = (N + (FRAC/MOD))*f_pfd
* N = f_vco/f_pfd - FRAC/MOD = f_vco*((R*(T+1))/(f_ref*(1+D))) - FRAC/MOD
* f_rf = f_vco/RFdiv)
* f_actual = f_rf/2
*/
for(R = 1; R <= 1023; R+=1){
//PFD input frequency = f_ref/R ... ignoring Reference doubler/divide-by-2 (D & T)
pfd_freq = ref_freq*(1+D)/(R*(1+T));
//keep the PFD frequency at or below 25MHz (Loop Filter Bandwidth)
if (pfd_freq > 25e6) continue;
//ignore fractional part of tuning
N = int(std::floor(vco_freq/pfd_freq));
//keep N > minimum int divider requirement
if (N < prescaler_to_min_int_div[prescaler]) continue;
for(BS=1; BS <= 255; BS+=1){
//keep the band select frequency at or below 100KHz
//constraint on band select clock
if (pfd_freq/BS > 100e3) continue;
goto done_loop;
}
} done_loop:
//Fractional-N calculation
MOD = 4095; //max fractional accuracy
FRAC = int((target_freq/pfd_freq - N)*MOD);
//Reference divide-by-2 for 50% duty cycle
// if R even, move one divide by 2 to to regs.reference_divide_by_2
if(R % 2 == 0){
T = adf4351_regs_t::REFERENCE_DIVIDE_BY_2_ENABLED;
R /= 2;
}
//actual frequency calculation
actual_freq = double((N + (double(FRAC)/double(MOD)))*ref_freq*(1+int(D))/(R*(1+int(T))));
UHD_LOGV(often)
<< boost::format("SBX Intermediates: ref=%0.2f, outdiv=%f, fbdiv=%f") % (ref_freq*(1+int(D))/(R*(1+int(T)))) % double(RFdiv*2) % double(N + double(FRAC)/double(MOD)) << std::endl
<< boost::format("SBX tune: R=%d, BS=%d, N=%d, FRAC=%d, MOD=%d, T=%d, D=%d, RFdiv=%d"
) % R % BS % N % FRAC % MOD % T % D % RFdiv << std::endl
<< boost::format("SBX Frequencies (MHz): REQ=%0.2f, ACT=%0.2f, VCO=%0.2f, PFD=%0.2f, BAND=%0.2f"
) % (target_freq/1e6) % (actual_freq/1e6) % (vco_freq/1e6) % (pfd_freq/1e6) % (pfd_freq/BS/1e6) << std::endl;
//load the register values
adf4351_regs_t regs;
if ((unit == dboard_iface::UNIT_TX) and (actual_freq == sbx_tx_lo_2dbm.clip(actual_freq)))
regs.output_power = adf4351_regs_t::OUTPUT_POWER_2DBM;
else
regs.output_power = adf4351_regs_t::OUTPUT_POWER_5DBM;
regs.frac_12_bit = FRAC;
regs.int_16_bit = N;
regs.mod_12_bit = MOD;
regs.clock_divider_12_bit = std::max(1, int(std::ceil(400e-6*pfd_freq/MOD)));
regs.feedback_select = adf4351_regs_t::FEEDBACK_SELECT_DIVIDED;
regs.clock_div_mode = adf4351_regs_t::CLOCK_DIV_MODE_RESYNC_ENABLE;
regs.prescaler = prescaler;
regs.r_counter_10_bit = R;
regs.reference_divide_by_2 = T;
regs.reference_doubler = D;
regs.band_select_clock_div = BS;
UHD_ASSERT_THROW(rfdivsel_to_enum.has_key(RFdiv));
regs.rf_divider_select = rfdivsel_to_enum[RFdiv];
//write the registers
//correct power-up sequence to write registers (5, 4, 3, 2, 1, 0)
int addr;
for(addr=5; addr>=0; addr--){
UHD_LOGV(often) << boost::format(
"SBX SPI Reg (0x%02x): 0x%08x"
) % addr % regs.get_reg(addr) << std::endl;
self_base->get_iface()->write_spi(
unit, spi_config_t::EDGE_RISE,
regs.get_reg(addr), 32
);
}
//return the actual frequency
UHD_LOGV(often) << boost::format(
"SBX tune: actual frequency %f Mhz"
) % (actual_freq/1e6) << std::endl;
return actual_freq;
}
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