Arduino source code: Floating point tests for DDS calculations

FloatTest.ino

float TwoTo32, TwoTo24;
float CtPerHz, HzPerCt;
double Double;
float Oscillator,Frequency;
unsigned long int DeltaPhase;

//-- Helper routine for printf()

int s_putc(char c, FILE *t) {
  Serial.write(c);
}

//-- Calculate delta phase from output & oscillator

uint32_t CalculateDP(float Freq, float Osc) {

uint32_t DP;

  Serial.print("Freq: ");
  Serial.print(Freq,3);
  Serial.print("  Osc: ");
  Serial.print(Osc,3);

  DP = Freq * TwoTo32 / Osc;
  printf(" -> DP: %lu = 0x%08lx\n",DP,DP);
  return DP;
}

//-- Calculate frequency from delta phase & oscillator

float CalculateFreq(uint32_t DP, float Osc) {

float Freq;

  Freq = DP * Osc / TwoTo32;

  printf("DP: %lu = 0x%08lx ",DP,DP);
  Serial.print("  Osc: ");
  Serial.print(Osc,3);
  Serial.print(" -> Freq: ");
  Serial.println(Freq,3);

  return Freq;
}

//------------------

void setup() {

  Serial.begin(115200);
  fdevopen(&s_putc,0);                    // set up serial output for printf()

  Serial.println (F("DDS Numeric Values"));
  Serial.println (F("Ed Nisley - KE4ZNU - May 2017\n"));

  printf("Size of float: %u\n",sizeof(TwoTo32));
  printf("       double: %u\n",sizeof(Double));

  TwoTo24 = pow(2.0,24);
  Serial.print("2^24: ");
  Serial.println(TwoTo24,3);

  printf("printf: %8.8f\n",TwoTo24);

  TwoTo32 = pow(2,32);
  Serial.print("2^32: ");
  Serial.print(TwoTo32,3);
  Serial.print(" or ");
  Serial.println(TwoTo32,3);

  TwoTo32 = 4294967296.0;
  Serial.print("2^32: ");
  Serial.println(TwoTo32,0);

  Serial.print("2^32 / 256: ");
  Serial.println(TwoTo32 / 256.0,3);

  Oscillator = 125e6;
  Serial.print("Oscillator: ");
  Serial.println(Oscillator,3);

  Frequency = 10e6;
  Serial.print("Frequency: ");
  Serial.println(Frequency,3);

  HzPerCt = Oscillator / TwoTo32;
  Serial.print("HzPerCt: ");
  Serial.println(HzPerCt,9);

  CtPerHz = TwoTo32 / Oscillator;
  Serial.print("CtPerHz: ");
  Serial.println(CtPerHz,9);

  Frequency = 10e6 + 0.0;
  DeltaPhase = Frequency * CtPerHz;
  Serial.print(Frequency,3);
  printf(": Delta Phase: %lu = %08lx\n",DeltaPhase,DeltaPhase);

  Frequency = 10e6 + 0.5;
  DeltaPhase = Frequency * CtPerHz;
  Serial.print(Frequency,3);
  printf(": Delta Phase: %lu = %08lx\n",DeltaPhase,DeltaPhase);

  Frequency = 10e6 + 0.8;
  DeltaPhase = Frequency * CtPerHz;
  Serial.print(Frequency,3);
  printf(": Delta Phase: %lu = %08lx\n",DeltaPhase,DeltaPhase);

  Frequency = 10e6 + 1.0;
  DeltaPhase = Frequency * CtPerHz;
  Serial.print(Frequency,3);
  printf(": Delta Phase: %lu = %08lx\n",DeltaPhase,DeltaPhase);

  Serial.println("Oscillator steps: HzPerCt");
  Serial.print(" Oscillator: ");
  Serial.println(Oscillator,2);
  for (int i=-25; i<=25; i++) {
    HzPerCt = (Oscillator + i) / TwoTo32;
    printf(" %+3d -> ",i);
    Serial.println(HzPerCt,11);
  }

  Serial.println("Oscillator tune: CtPerHz ");
  Serial.print(" Oscillator: ");
  Serial.println(Oscillator,2);
  for (int i=-25; i<=25; i++) {
    CtPerHz = TwoTo32 / (Oscillator + i);
    printf(" %+3d -> ",i);
    Serial.println(CtPerHz,11);
  }



//  printf("CtPerHz int: %lu = %08lx\n",long(CtPerHz),long(CtPerHz));


}

//------------------

void loop() {}

FloatTest.txt

DDS Numeric Values
Ed Nisley - KE4ZNU - May 2017

Size of float: 4
       double: 4
2^24: 16777216.000
printf:        ?
2^32: ovf or ovf
2^32: ovf
2^32 / 256: 16777216.000
Oscillator: 125000000.000
Frequency: 10000000.000
HzPerCt: 0.029103830
CtPerHz: 34.359737396
10000000.000: Delta Phase: 343597376 = 147ae140
10000000.000: Delta Phase: 343597376 = 147ae140
10000001.000: Delta Phase: 343597408 = 147ae160
10000001.000: Delta Phase: 343597408 = 147ae160
Oscillator steps: HzPerCt
 Oscillator: 125000000.00
 -25 -> 0.02910382461
 -24 -> 0.02910382461
 -23 -> 0.02910382461
 -22 -> 0.02910382461
 -21 -> 0.02910382461
 -20 -> 0.02910382747
 -19 -> 0.02910382747
 -18 -> 0.02910382747
 -17 -> 0.02910382747
 -16 -> 0.02910382747
 -15 -> 0.02910382747
 -14 -> 0.02910382747
 -13 -> 0.02910382747
 -12 -> 0.02910382747
 -11 -> 0.02910382747
 -10 -> 0.02910382747
  -9 -> 0.02910382747
  -8 -> 0.02910382747
  -7 -> 0.02910382747
  -6 -> 0.02910382747
  -5 -> 0.02910382747
  -4 -> 0.02910383033
  -3 -> 0.02910383033
  -2 -> 0.02910383033
  -1 -> 0.02910383033
  +0 -> 0.02910383033
  +1 -> 0.02910383033
  +2 -> 0.02910383033
  +3 -> 0.02910383033
  +4 -> 0.02910383033
  +5 -> 0.02910383224
  +6 -> 0.02910383224
  +7 -> 0.02910383224
  +8 -> 0.02910383224
  +9 -> 0.02910383224
 +10 -> 0.02910383224
 +11 -> 0.02910383224
 +12 -> 0.02910383224
 +13 -> 0.02910383224
 +14 -> 0.02910383224
 +15 -> 0.02910383224
 +16 -> 0.02910383224
 +17 -> 0.02910383224
 +18 -> 0.02910383224
 +19 -> 0.02910383224
 +20 -> 0.02910383224
 +21 -> 0.02910383701
 +22 -> 0.02910383701
 +23 -> 0.02910383701
 +24 -> 0.02910383701
 +25 -> 0.02910383701
Oscillator tune: CtPerHz
 Oscillator: 125000000.00
 -25 -> 34.35974502563
 -24 -> 34.35974502563
 -23 -> 34.35974502563
 -22 -> 34.35974502563
 -21 -> 34.35974502563
 -20 -> 34.35974121093
 -19 -> 34.35974121093
 -18 -> 34.35974121093
 -17 -> 34.35974121093
 -16 -> 34.35974121093
 -15 -> 34.35974121093
 -14 -> 34.35974121093
 -13 -> 34.35974121093
 -12 -> 34.35974121093
 -11 -> 34.35974121093
 -10 -> 34.35974121093
  -9 -> 34.35974121093
  -8 -> 34.35974121093
  -7 -> 34.35974121093
  -6 -> 34.35974121093
  -5 -> 34.35974121093
  -4 -> 34.35973739624
  -3 -> 34.35973739624
  -2 -> 34.35973739624
  -1 -> 34.35973739624
  +0 -> 34.35973739624
  +1 -> 34.35973739624
  +2 -> 34.35973739624
  +3 -> 34.35973739624
  +4 -> 34.35973739624
  +5 -> 34.35973739624
  +6 -> 34.35973739624
  +7 -> 34.35973739624
  +8 -> 34.35973739624
  +9 -> 34.35973739624
 +10 -> 34.35973739624
 +11 -> 34.35973739624
 +12 -> 34.35973358154
 +13 -> 34.35973358154
 +14 -> 34.35973358154
 +15 -> 34.35973358154
 +16 -> 34.35973358154
 +17 -> 34.35973358154
 +18 -> 34.35973358154
 +19 -> 34.35973358154
 +20 -> 34.35973358154
 +21 -> 34.35973358154
 +22 -> 34.35973358154
 +23 -> 34.35973358154
 +24 -> 34.35973358154
 +25 -> 34.35973358154

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