Add frequency error

src/gpio.cpp

@@ -194,7 +194,7 @@ int clkgpio::ComputeBestLO(uint64_t Frequency,int Bandwidth)
       best_divider=0;
       for( divider=1;divider<4096;divider++)
       {
-        if( Frequency*divider <  300e6 ) continue; // widest accepted frequency range
+        if( Frequency*divider <  600e6 ) continue; // widest accepted frequency range
         if( Frequency*divider > 1500e6 ) break;
 
         max_int_multiplier=((int)((double)(Frequency+Bandwidth)*divider*xtal_freq_recip));
@@ -258,6 +258,17 @@ double clkgpio::GetFrequencyResolution()
 	return res;
 }
 
+double clkgpio::GetRealFrequency(double Frequency)
+{
+	double FloatMult=((double)(CentralFrequency+Frequency)*PllFixDivider)/(double)(XOSC_FREQUENCY);
+	uint32_t freqctl = FloatMult*((double)(1<<20)) ; 
+	int IntMultiply= freqctl>>20; // Need to be calculated to have a center frequency
+	freqctl&=0xFFFFF; // Fractionnal is 20bits
+	uint32_t FracMultiply=freqctl&0xFFFFF; 
+	double RealFrequency=((double)IntMultiply+(FracMultiply/(double)(1<<20)))*(double)(XOSC_FREQUENCY)/PllFixDivider-(CentralFrequency+Frequency);
+	return RealFrequency;	
+}
+
 int clkgpio::SetCenterFrequency(uint64_t Frequency,int Bandwidth)
 {
 	CentralFrequency=Frequency;

src/gpio.h

@@ -162,6 +162,7 @@ class clkgpio:public gpio
 	void SetAdvancedPllMode(bool Advanced);
 	int SetCenterFrequency(uint64_t Frequency,int Bandwidth);
 	double GetFrequencyResolution();
+	double GetRealFrequency(double Frequency);
 	int ComputeBestLO(uint64_t Frequency,int Bandwidth);
 	int SetMasterMultFrac(uint32_t Mult,uint32_t Frac);
 	uint32_t GetMasterFrac(double Frequency);