Merge pull request #46 from etherkit/v2.0.4

Fix error in VCXO algorithm

Author: NT7S

README.md

@@ -249,6 +249,8 @@ PLLA and PLLB are set to 800 MHz (also defined as _SI5351_PLL_FIXED_ in the libr
 
 All CLK outputs are set to 0 Hz and disabled.
 
+Default drive strength is 2 mA on each output.
+
 Constraints
 -----------
 * Two multisynths cannot share a PLL with when both outputs are >= 100 MHz. The library will refuse to set another multisynth to a frequency in that range if another multisynth sharing the same PLL is already within that frequency range.
@@ -663,6 +665,10 @@ This library does not currently support the spread spectrum function of the Si53
 
 Changelog
 ---------
+* v2.0.4
+
+    * Fix error in VCXO algorithm
+
 * v2.0.3
 
     * Fix regression in _set_freq()_ that wiped out proper R div setting, causing errors in setting low frequency outputs

library.properties

@@ -1,5 +1,5 @@
 name=Etherkit Si5351
-version=2.0.3
+version=2.0.4
 author=Jason Milldrum <[email protected]>
 maintainer=Jason Milldrum <[email protected]>
 sentence=A full-featured library for the Si5351 series of clock generator ICs from Silicon Labs

src/si5351.cpp

@@ -1197,7 +1197,7 @@ void Si5351::set_vcxo(uint64_t pll_freq, uint8_t ppm)
 	delete params;
 
 	// Write the VCXO parameters
-	vcxo_param = (vcxo_param * ppm) / RFRAC_DENOM;
+	vcxo_param = ((vcxo_param * ppm * SI5351_VCXO_MARGIN) / 100ULL) / 1000000ULL;
 
 	temp = (uint8_t)(vcxo_param & 0xFF);
 	si5351_write(SI5351_VXCO_PARAMETERS_LOW, temp);
@@ -1319,7 +1319,7 @@ uint64_t Si5351::pll_calc(uint64_t freq, struct Si5351RegSet *reg, int32_t corre
 
 	if(vcxo)
 	{
-		return (uint64_t)(128 * a * SI5351_VCXO_MARGIN + b * SI5351_VCXO_MARGIN);
+		return (uint64_t)(128 * a * 1000000ULL + b);
 	}
 	else
 	{

src/si5351.h

@@ -69,7 +69,7 @@
 #define SI5351_MULTISYNTH_P3_MAX        ((1<<20)-1)
 #define SI5351_VCXO_PULL_MIN            30
 #define SI5351_VCXO_PULL_MAX            240
-#define SI5351_VCXO_MARGIN              1030000
+#define SI5351_VCXO_MARGIN              103
 
 #define SI5351_DEVICE_STATUS            0
 #define SI5351_INTERRUPT_STATUS         1