Made driver for si5351

Also included some of Guido's trig approximations (magn, arctan3)

NIL-STM32F051-DISCOVERY/.cproject

@@ -67,9 +67,7 @@
                     					
                     <sourceEntries>
                         						
-                        <entry excluding="radio" flags="VALUE_WORKSPACE_PATH|RESOLVED" kind="sourcePath" name=""/>
-                        						
-                        <entry flags="VALUE_WORKSPACE_PATH|RESOLVED" kind="sourcePath" name="radio"/>
+                        <entry flags="VALUE_WORKSPACE_PATH|RESOLVED" kind="sourcePath" name=""/>
                         					
                     </sourceEntries>
                     				

NIL-STM32F051-DISCOVERY/Makefile

@@ -120,7 +120,7 @@ LDSCRIPT= $(STARTUPLD)/STM32F051x8.ld
 # setting.
 CSRC = $(ALLCSRC) \
        $(TESTSRC) \
-       main.c radio/rx.c
+       main.c radio/rx.c drivers/si5351.c trig.c
 
 # C++ sources that can be compiled in ARM or THUMB mode depending on the global
 # setting.

NIL-STM32F051-DISCOVERY/drivers/si5351.c

@@ -0,0 +1,87 @@
+/*
+ * si5351.c
+ *
+ *  Created on: Jul 7, 2020
+ *      Author: marshal
+ */
+#include "si5351.h"
+#include "../trig.h"
+
+void synth_en(struct synth * cfg){
+  uint8_t buf[2];
+  buf[0]=cfg->channel+16;
+  buf[1]=cfg->PLLx ? 0x2F : 0x1F;
+  const uint8_t si5351 = 0x60;
+  i2cMasterTransmitTimeout(&I2CD1, si5351, buf, 2,
+                             NULL, 0, TIME_MS2I(100));
+}
+
+void synth_write_params(uint8_t reg, uint64_t val, uint8_t div){
+  uint8_t buf[9];
+  buf[0]=reg*8+26;
+  buf[1]=0xFF; // denominator is always 0xFFFFF
+  buf[2]=0xFF;
+  buf[3]=val>>36 & 0x03;
+  buf[3]|=div<<4;
+  buf[4]=val>>28;
+  buf[5]=val>>20;
+  buf[6]=val>>16 | 0xF0;
+  buf[7]=val>>8;
+  buf[8]=val;
+
+  const uint8_t si5351 = 0x60;
+  i2cMasterTransmitTimeout(&I2CD1, si5351, buf, 9, NULL, 0, TIME_MS2I(100));
+}
+
+void synth_set_carrier(struct synth * cfg, float carrier){
+  // Calculate PLL and Multisynth values
+  const double xtal = 27e6;
+  double pll = 27; // Good starting value to put vxco at 750MHz
+  double div = xtal * pll / carrier;
+  double delta = div - (xtal*pll)/(carrier+1); // Linearized change per Hz
+  int8_t delta_shift = round(log2(delta)); // round to nearest power of 2
+  double delta2 = (0x40000000>>delta_shift)*(1.0/0x40000000U); // (Computing a negative power of 2)
+  div *= delta2/delta;
+  div = round(div/2)*2+1;   // Minimize chance of rollover
+  pll = carrier * div / xtal; // Adjust pll to match
+
+  // If desired frequency is very low, we need to use the additional divider register
+  uint8_t div2;
+  for(div2=0; div>2048; ++div2){
+    div *= 0.5;
+    --delta_shift;
+  }
+
+  // Store values into config
+  const uint32_t fixed_shift = 1<<27;   //For shifting values to fixed-point
+  cfg->reg.pll = pll * fixed_shift;
+  cfg->reg.synth = div * fixed_shift;
+  cfg->reg.shift = delta_shift;
+  cfg->reg.divide = div2;
+
+  // Write changes to chip
+  synth_write_params(cfg->PLLx, cfg->reg.pll, 0);
+  synth_write_params(cfg->channel+2, cfg->reg.synth, cfg->reg.divide);
+  synth_en(cfg);
+}
+
+void synth_set_baseband(struct synth * cfg, int32_t baseband){
+  int32_t diff = baseband - cfg->baseband;
+  diff >>= cfg->reg.shift;
+  cfg->reg.synth -= diff;
+  uint32_t val = cfg->reg.synth;
+  uint8_t buf[5];
+  /* This could potentially be sped up by dropping the last byte */
+  buf[0]=8*(cfg->channel)+46;
+  buf[1]=val>>20;
+  buf[2]=(val>>16) | 0xF0;
+  buf[3]=val>>8;
+  buf[4]=val;
+  const uint8_t si5351 = 0x60;
+  i2cMasterTransmitTimeout(&I2CD1, si5351, buf, 5,NULL, 0, TIME_MS2I(100));
+}
+
+void synth_init(struct synth * cfg, uint8_t channel, uint8_t pll){
+  cfg->channel = channel;
+  cfg->PLLx = pll;
+}

NIL-STM32F051-DISCOVERY/drivers/si5351.h

@@ -0,0 +1,33 @@
+/*
+ * si5351.h
+ *
+ *  Created on: Jul 8, 2020
+ *      Author: marshal
+ */
+
+#ifndef SI5351_H_
+#define SI5351_H_
+
+#include "hal.h"
+
+struct synth{
+  float carrier; //< in Hz
+  int32_t baseband; //< 15.16 fixed-point, in Hz
+  struct { //< Calculated values for setting registers
+    uint64_t pll:38;    //< 11.27 fixed-point for PLL multipler
+    uint64_t synth:38;  //< 11.27 fixed-point for Synth Divider
+    uint8_t divide:2;   //< 4-bit field for extra divider settings
+    int8_t shift;      //< Shift value for scaling the baseband frequency
+  }reg;
+  uint8_t channel:2; //Supports four channels - increase bit width if more are desired
+  uint8_t PLLx:1;  //< 0 is PLLA, 1 is PLLB
+};
+
+void synth_init(struct synth * cfg, uint8_t channel, uint8_t pll);
+void synth_en(struct synth * cfg);
+void synth_set_carrier(struct synth * cfg, float carrier);
+void synth_set_baseband(struct synth * cfg, int32_t baseband);
+void synth_write_params(uint8_t reg, uint64_t val, uint8_t div);
+
+
+#endif /* SI5351_H_ */

NIL-STM32F051-DISCOVERY/trig.c

@@ -0,0 +1,20 @@
+/*
+ * trig.c
+ *
+ *  Created on: Jul 6, 2020
+ *      Author: marshal
+ */
+#include "trig.h"
+
+inline int16_t arctan3(int16_t q, int16_t i)  // error ~ 0.8 degree
+{ // source: [1] http://www-labs.iro.umontreal.ca/~mignotte/IFT2425/Documents/EfficientApproximationArctgFunction.pdf
+#define _atan2(z)  (_UA/8 - _UA/22 * z + _UA/22) * z  //derived from (5) [1]
+  //#define _atan2(z)  (_UA/8 - _UA/24 * z + _UA/24) * z  //derived from (7) [1]
+  int16_t r;
+  if(abs(q) > abs(i))
+    r = _UA / 4 - _atan2(abs(i) / abs(q));        // arctan(z) = 90-arctan(1/z)
+  else
+    r = (i == 0) ? 0 : _atan2(abs(q) / abs(i));   // arctan(z)
+  r = (i < 0) ? _UA / 2 - r : r;                  // arctan(-z) = -arctan(z)
+  return (q < 0) ? -r : r;                        // arctan(-z) = -arctan(z)
+}

NIL-STM32F051-DISCOVERY/trig.h

@@ -0,0 +1,25 @@
+/*
+ * trig.h
+ *
+ *  Created on: Jul 8, 2020
+ *      Author: marshal
+ */
+
+#ifndef TRIG_H_
+#define TRIG_H_
+
+#include <math.h>
+#include <stdint.h>
+
+#define F_SAMP_TX 4810        //4810 // ADC sample-rate; is best a multiple of _UA and fits exactly in OCR0A = ((F_CPU / 64) / F_SAMP_TX) - 1 , should not exceed CPU utilization
+#define _UA  (F_SAMP_TX)      //360  // unit angle; integer representation of one full circle turn or 2pi radials or 360 degrees, should be a integer divider of F_SAMP_TX and maximized to have higest precision
+
+// Stdlib includes abs, but I'm not sure we want it. This works for all numerical types.
+#define abs(x) (x>=0?x:-x)
+
+int16_t arctan3(int16_t q, int16_t i);
+
+#define magn(i, q) (abs(i) > abs(q) ? abs(i) + abs(q) / 4 : abs(q) + abs(i) / 4) // approximation of: magnitude = sqrt(i*i + q*q); error 0.95dB
+
+
+#endif /* TRIG_H_ */