TVRX: First version that works. The gain linearity is still borked.

I'll probably give up on the complicated linearizing stuff and just use the values from the old driver. The tuner's gain-vs-voltage is nothing like the datasheet.

1 files changed, 31 insertions, 13 deletions

diff --git a/host/lib/usrp/dboard/db_tvrx.cpp b/host/lib/usrp/dboard/db_tvrx.cpp
index 2988367e2..f5b544c18 100644
--- a/host/lib/usrp/dboard/db_tvrx.cpp
+++ b/host/lib/usrp/dboard/db_tvrx.cpp
@@ -44,6 +44,7 @@
 #include <utility>
 #include <cmath>
 #include <cfloat>
+#include <limits>
 #include <tuner_4937di5_regs.hpp>
 
 using namespace uhd;
@@ -59,10 +60,6 @@ static const freq_range_t tvrx_freq_range(50e6, 860e6);
 
 static const std::string tvrx_antennas = std::string(""); //only got one
 
-//a note on these: the gain of the TVRX varies over frequency. the gain ranges
-//below correspond to the maximum and minimum gains over the entire frequency range.
-//specifying a gain higher or lower than the TVRX can accomplish will of course just clip.
-
 static const uhd::dict<std::string, freq_range_t> tvrx_freq_ranges = map_list_of
     ("VHFLO", freq_range_t(50e6, 158e6))
     ("VHFHI", freq_range_t(158e6, 454e6))
@@ -148,7 +145,7 @@ private:
     double _lo_freq;
     tuner_4937di5_regs_t _tuner_4937di5_regs;
     boost::uint8_t _tuner_4937di5_addr(void){
-        return (this->get_iface()->get_special_props().mangle_i2c_addrs)? 0x60 : 0x61; //ok really? we could rename that call
+        return (this->get_iface()->get_special_props().mangle_i2c_addrs)? 0x61 : 0x60; //ok really? we could rename that call
     };
 
     void set_gain(float gain, const std::string &name);
@@ -182,7 +179,7 @@ static dboard_base::sptr make_tvrx(dboard_base::ctor_args_t args){
 
 UHD_STATIC_BLOCK(reg_tvrx_dboard){
     //register the factory function for the rx dbid
-    dboard_manager::register_dboard(0x0003, &make_tvrx, "tvrx");
+    dboard_manager::register_dboard(0x0040, &make_tvrx, "tvrx");
 }
 
 /***********************************************************************
@@ -203,6 +200,7 @@ tvrx::tvrx(ctor_args_t args) : rx_dboard_base(args){
     //send initial register settings if necessary
     
     //set default freq
+    _lo_freq = tvrx_freq_range.min + tvrx_if_freq; //init _lo_freq to a sane default
     set_freq(tvrx_freq_range.min);
     
     //set default gains
@@ -220,9 +218,12 @@ tvrx::~tvrx(void){
  */
 
 static std::string get_band(double freq) {
+    std::cout << "get_band called with freq " << freq << std::endl;
     BOOST_FOREACH(const std::string &band, tvrx_freq_ranges.keys()) {
-        if(freq >= tvrx_freq_ranges[band].min && freq <= tvrx_freq_ranges[band].max)
+        if(freq >= tvrx_freq_ranges[band].min && freq <= tvrx_freq_ranges[band].max){
+            std::cout << "Holy poop you're in band " << band << std::endl;
             return band;
+        }
     }
     UHD_THROW_INVALID_CODE_PATH();
 }
@@ -245,15 +246,25 @@ static float gain_interp(float gain, boost::array<float, 17> db_vector, boost::a
     boost::uint8_t gain_step = 0;
     //find which bin we're in
     for(size_t i = 0; i < db_vector.size()-1; i++) {
-        if(gain > db_vector[i] && gain < db_vector[i+1]) gain_step = i;
+        if(gain >= db_vector[i] && gain <= db_vector[i+1]) gain_step = i;
     }
     
     //find the current slope for linear interpolation
     float slope = (volts_vector[gain_step + 1] - volts_vector[gain_step]) 
                 / (db_vector[gain_step + 1] - db_vector[gain_step]);
+                
+    //the problem here is that for gains approaching the maximum, the voltage slope becomes infinite
+    //i.e., a small change in gain requires an infinite change in voltage
+    //to cope, we limit the slope
+    
+    if(slope == std::numeric_limits<float>::infinity())
+        return volts_vector[gain_step];
 
     //use the volts per dB slope to find the final interpolated voltage
     volts = volts_vector[gain_step] + (slope * (gain - db_vector[gain_step]));
+        
+    if(tvrx_debug)
+        std::cout << "Gain interp: gain: " << gain << ", gain_step: " << int(gain_step) << ", slope: " << slope << ", volts: " << volts << std::endl;
     
     return volts;
 }
@@ -276,6 +287,8 @@ static float rf_gain_to_voltage(float gain, double lo_freq){
     float gain_volts = gain_interp(gain, tvrx_rf_gains_db[band], tvrx_gains_volts);
     //this is the voltage at the USRP DAC output
     float dac_volts = gain_volts / opamp_gain;
+    
+    dac_volts = std::clip<float>(dac_volts, 0.0, 3.3);
 
     if (tvrx_debug) std::cerr << boost::format(
         "tvrx RF AGC gain: %f dB, dac_volts: %f V"
@@ -297,6 +310,8 @@ static float if_gain_to_voltage(float gain){
     
     float gain_volts = gain_interp(gain, tvrx_if_gains_db, tvrx_gains_volts);
     float dac_volts = gain_volts / opamp_gain;
+    
+    dac_volts = std::clip<float>(dac_volts, 0.0, 3.3);
 
     if (tvrx_debug) std::cerr << boost::format(
         "tvrx IF AGC gain: %f dB, dac_volts: %f V"
@@ -324,13 +339,13 @@ void tvrx::set_gain(float gain, const std::string &name){
 
 void tvrx::set_freq(double freq) {
     freq = std::clip<float>(freq, tvrx_freq_range.min, tvrx_freq_range.max);
-    std::string prev_band = get_band(_lo_freq + tvrx_if_freq);
+    std::string prev_band = get_band(_lo_freq - tvrx_if_freq);
     std::string new_band = get_band(freq);
     
-    double lo_freq = freq + tvrx_if_freq; //the desired LO freq for high-side mixing
+    double target_lo_freq = freq + tvrx_if_freq; //the desired LO freq for high-side mixing
     double f_ref = reference_freq / double(reference_divider); //your tuning step size
     
-    int divisor = int(lo_freq + (f_ref * 4.0)) / (f_ref * 8); //the divisor we'll use
+    int divisor = int((target_lo_freq + (f_ref * 4.0)) / (f_ref * 8)); //the divisor we'll use
     double actual_lo_freq = (f_ref * 8 * divisor); //the LO freq we'll actually get
     
     if((divisor & ~0x7fff)) UHD_THROW_INVALID_CODE_PATH();
@@ -344,7 +359,7 @@ void tvrx::set_freq(double freq) {
     else if(new_band == "UHF") _tuner_4937di5_regs.bandsel = tuner_4937di5_regs_t::BANDSEL_UHF;
     else UHD_THROW_INVALID_CODE_PATH();
     
-    _tuner_4937di5_regs.power = tuner_4937di5_regs_t::POWER_ON;
+    _tuner_4937di5_regs.power = tuner_4937di5_regs_t::POWER_OFF;
     update_regs();
 
     //ok don't forget to reset RF gain here if the new band != the old band
@@ -352,6 +367,9 @@ void tvrx::set_freq(double freq) {
     //not FAR off, but we do this to be consistent
     if(prev_band != new_band) set_gain(_gains["RF"], "RF");
     
+    if(tvrx_debug) 
+        std::cout << boost::format("set_freq: target LO: %f f_ref: %f divisor: %i actual LO: %f") % target_lo_freq % f_ref % divisor % actual_lo_freq << std::endl;
+    
     _lo_freq = actual_lo_freq; //for rx props
 }
 
@@ -386,7 +404,7 @@ void tvrx::rx_get(const wax::obj &key_, wax::obj &val){
         return;
 
     case SUBDEV_PROP_FREQ:
-        val = _lo_freq - tvrx_if_freq;
+        val = _lo_freq - 2*tvrx_if_freq;
         return;
 
     case SUBDEV_PROP_FREQ_RANGE: