HamShield/DDS.h

#ifndef _DDS_H_
#define _DDS_H_
#include <Arduino.h>
#include <avr/pgmspace.h>

// Just a little (useless?) reminder; #warnings are not displayed in Arduino IDE.
#ifndef __SAMD21G18A__
#warning Experimental support for ArduinoZero.  Not yet complete.
#endif 

// For AVRs:
// Use pin 3 for PWM? If not defined, use pin 11
// Quality on pin 3 is higher than on 11, as it can be clocked faster
// when the COMPARATOR_BITS value is less than 8
// #define DDS_PWM_PIN_3

// For AVRs:
// Normally, we turn on timer2 and timer1, and have ADC sampling as our clock
// Define this to only use Timer2, and not start the ADC clock
// #define DDS_USE_ONLY_TIMER2

// Use a short (16 bit) accumulator. Phase accuracy is reduced, but speed
// is increased, along with a reduction in memory use._
#define SHORT_ACCUMULATOR

#ifdef SHORT_ACCUMULATOR
#define ACCUMULATOR_BITS      16
typedef uint16_t ddsAccumulator_t;
#else
#define ACCUMULATOR_BITS      32
typedef uint32_t ddsAccumulator_t;
#endif

// The maximum value of the accumulator based on the number of bits
// Macro for code readability.
#define DDS_MAX_ACCUMULATOR (pow(2,ACCUMULATOR_BITS))

// If defined, the timer will idle at 50% duty cycle
// This leaves it floating in the centre of the PWM/DAC voltage range
#define DDS_IDLE_HIGH

// For AVRs:
// Select how fast the PWM is, at the expense of level accuracy.
// A faster PWM rate will make for easier filtering of the output wave,
// while a slower one will allow for more accurate voltage level outputs,
// but will increase the filtering requirements on the output.
// 8 = 62.5kHz PWM
// 7 = 125kHz PWM
// 6 = 250kHz PWM
// For SAMD21's -- the resolution of the DAC.

#ifdef __SAMD21G18A__
  #define COMPARATOR_BITS       10
  typedef uint16_t ddsComparitor_t;
#elif defined(DDS_PWM_PIN_3)
  #define COMPARATOR_BITS       6
  typedef uint8_t ddsComparitor_t;
#else // When using pin 11, we always want 8 bits
  #define COMPARATOR_BITS       8
  typedef uint8_t ddsComparitor_t;
#endif

// The maximum value of the comparitor based on the number of bits
// Macro for code readability.
#define DDS_MAX_COMPARATOR pow(2,COMPARATOR_BITS)

// This is how often we'll perform a phase advance, as well as ADC sampling
// rate. The higher this value, the smoother the output wave will be, at the
// expense of CPU time. 
// For AVRs: It maxes out around 62000 (TBD)  May be overridden in the sketch 
// to improve performance
#ifndef DDS_REFCLK_DEFAULT
  #ifdef __SAMD21G18A__
    #define DDS_REFCLK_DEFAULT     44100
  #else
    #define DDS_REFCLK_DEFAULT     9600
  #endif
#endif

// As each Arduino crystal is a little different, this can be fine tuned to
// provide more accurate frequencies. Adjustments in the range of hundreds
// is a good start.
#ifndef DDS_REFCLK_OFFSET
#define DDS_REFCLK_OFFSET     0
#endif

#ifdef DDS_USE_ONLY_TIMER2
// TODO: Figure out where this clock value is generated from
#define DDS_REFCLK_DEFAULT     (62500/4)
#endif

// Output some of the calculations and information about the DDS over serial
#define DDS_DEBUG_SERIAL

// When defined, use the 1024 element sine lookup table. This improves phase
// accuracy, at the cost of more flash and CPU requirements.
// #define DDS_TABLE_LARGE

// When defined, use a 10-bit table of short integers.  This is wasteful of
// flash space as there are 6 bits of each value that are unused.
// May improve resolution.  When set, "DDS_TABLE_LARGE" is ignored.
// #define DDS_TABLE_10BIT

#ifdef DDS_TABLE_10BIT

// 10-bit Large SineTable, 1024 values +/-511
// Generated using http://www.meraman.com/htmls/en/sinTable.html
#define ACCUMULATOR_BIT_SHIFT (ACCUMULATOR_BITS-10)
#define DDS_LOOKUPVALUE_BITS 10
static const int16_t ddsSineTable[1024] PROGMEM = {0, 3, 6, 9, 13, 16, 19, 22, 25, 28, 31, 34, 38, 41, 44, 47, 50, 53,
   56, 59, 63, 66, 69, 72, 75, 78, 81, 84, 87, 90, 94, 97, 100, 103, 106, 109, 112, 115, 118, 121, 124, 127, 130, 133, 136,
   139, 142, 145, 148, 151, 154, 157, 160, 163, 166, 169, 172, 175, 178, 181, 184, 187, 190, 193, 196, 198, 201, 204, 207,
   210, 213, 216, 218, 221, 224, 227, 230, 233, 235, 238, 241, 244, 246, 249, 252, 255, 257, 260, 263, 265, 268, 271, 273,
   276, 279, 281, 284, 286, 289, 292, 294, 297, 299, 302, 304, 307, 309, 312, 314, 317, 319, 322, 324, 327, 329, 331, 334,
   336, 338, 341, 343, 345, 348, 350, 352, 355, 357, 359, 361, 364, 366, 368, 370, 372, 374, 377, 379, 381, 383, 385, 387,
   389, 391, 393, 395, 397, 399, 401, 403, 405, 407, 409, 410, 412, 414, 416, 418, 420, 421, 423, 425, 427, 428, 430, 432,
   433, 435, 437, 438, 440, 441, 443, 445, 446, 448, 449, 451, 452, 454, 455, 456, 458, 459, 461, 462, 463, 465, 466, 467,
   468, 470, 471, 472, 473, 474, 476, 477, 478, 479, 480, 481, 482, 483, 484, 485, 486, 487, 488, 489, 490, 491, 492, 492,
   493, 494, 495, 496, 496, 497, 498, 499, 499, 500, 501, 501, 502, 502, 503, 503, 504, 505, 505, 505, 506, 506, 507, 507,
   508, 508, 508, 509, 509, 509, 509, 510, 510, 510, 510, 510, 511, 511, 511, 511, 511, 511, 511, 511, 511, 511, 511, 511,
   511, 511, 511, 510, 510, 510, 510, 510, 509, 509, 509, 509, 508, 508, 508, 507, 507, 506, 506, 505, 505, 505, 504, 503,
   503, 502, 502, 501, 501, 500, 499, 499, 498, 497, 496, 496, 495, 494, 493, 492, 492, 491, 490, 489, 488, 487, 486, 485,
   484, 483, 482, 481, 480, 479, 478, 477, 476, 474, 473, 472, 471, 470, 468, 467, 466, 465, 463, 462, 461, 459, 458, 456,
   455, 454, 452, 451, 449, 448, 446, 445, 443, 441, 440, 438, 437, 435, 433, 432, 430, 428, 427, 425, 423, 421, 420, 418,
   416, 414, 412, 410, 409, 407, 405, 403, 401, 399, 397, 395, 393, 391, 389, 387, 385, 383, 381, 379, 377, 374, 372, 370,
   368, 366, 364, 361, 359, 357, 355, 352, 350, 348, 345, 343, 341, 338, 336, 334, 331, 329, 327, 324, 322, 319, 317, 314,
   312, 309, 307, 304, 302, 299, 297, 294, 292, 289, 286, 284, 281, 279, 276, 273, 271, 268, 265, 263, 260, 257, 255, 252,
   249, 246, 244, 241, 238, 235, 233, 230, 227, 224, 221, 218, 216, 213, 210, 207, 204, 201, 198, 196, 193, 190, 187, 184,
   181, 178, 175, 172, 169, 166, 163, 160, 157, 154, 151, 148, 145, 142, 139, 136, 133, 130, 127, 124, 121, 118, 115, 112,
   109, 106, 103, 100, 97, 94, 90, 87, 84, 81, 78, 75, 72, 69, 66, 63, 59, 56, 53, 50, 47, 44, 41, 38, 34, 31, 28, 25, 22,
   19, 16, 13, 9, 6, 3, 0, -3, -6, -9, -13, -16, -19, -22, -25, -28, -31, -34, -38, -41, -44, -47, -50, -53, -56, -59, -63,
   -66, -69, -72, -75, -78, -81, -84, -87, -90, -94, -97, -100, -103, -106, -109, -112, -115, -118, -121, -124, -127, -130,
   -133, -136, -139, -142, -145, -148, -151, -154, -157, -160, -163, -166, -169, -172, -175, -178, -181, -184, -187, -190,
   -193, -196, -198, -201, -204, -207, -210, -213, -216, -218, -221, -224, -227, -230, -233, -235, -238, -241, -244, -246,
   -249, -252, -255, -257, -260, -263, -265, -268, -271, -273, -276, -279, -281, -284, -286, -289, -292, -294, -297, -299,
   -302, -304, -307, -309, -312, -314, -317, -319, -322, -324, -327, -329, -331, -334, -336, -338, -341, -343, -345, -348,
   -350, -352, -355, -357, -359, -361, -364, -366, -368, -370, -372, -374, -377, -379, -381, -383, -385, -387, -389, -391,
   -393, -395, -397, -399, -401, -403, -405, -407, -409, -410, -412, -414, -416, -418, -420, -421, -423, -425, -427, -428,
   -430, -432, -433, -435, -437, -438, -440, -441, -443, -445, -446, -448, -449, -451, -452, -454, -455, -456, -458, -459,
   -461, -462, -463, -465, -466, -467, -468, -470, -471, -472, -473, -474, -476, -477, -478, -479, -480, -481, -482, -483,
   -484, -485, -486, -487, -488, -489, -490, -491, -492, -492, -493, -494, -495, -496, -496, -497, -498, -499, -499, -500,
   -501, -501, -502, -502, -503, -503, -504, -505, -505, -505, -506, -506, -507, -507, -508, -508, -508, -509, -509, -509,
   -509, -510, -510, -510, -510, -510, -511, -511, -511, -511, -511, -511, -511, -511, -511, -511, -511, -511, -511, -511,
   -511, -510, -510, -510, -510, -510, -509, -509, -509, -509, -508, -508, -508, -507, -507, -506, -506, -505, -505, -505,
   -504, -503, -503, -502, -502, -501, -501, -500, -499, -499, -498, -497, -496, -496, -495, -494, -493, -492, -492, -491,
   -490, -489, -488, -487, -486, -485, -484, -483, -482, -481, -480, -479, -478, -477, -476, -474, -473, -472, -471, -470,
   -468, -467, -466, -465, -463, -462, -461, -459, -458, -456, -455, -454, -452, -451, -449, -448, -446, -445, -443, -441,
   -440, -438, -437, -435, -433, -432, -430, -428, -427, -425, -423, -421, -420, -418, -416, -414, -412, -410, -409, -407,
   -405, -403, -401, -399, -397, -395, -393, -391, -389, -387, -385, -383, -381, -379, -377, -374, -372, -370, -368, -366,
   -364, -361, -359, -357, -355, -352, -350, -348, -345, -343, -341, -338, -336, -334, -331, -329, -327, -324, -322, -319,
   -317, -314, -312, -309, -307, -304, -302, -299, -297, -294, -292, -289, -286, -284, -281, -279, -276, -273, -271, -268,
   -265, -263, -260, -257, -255, -252, -249, -246, -244, -241, -238, -235, -233, -230, -227, -224, -221, -218, -216, -213,
   -210, -207, -204, -201, -198, -196, -193, -190, -187, -184, -181, -178, -175, -172, -169, -166, -163, -160, -157, -154,
   -151, -148, -145, -142, -139, -136, -133, -130, -127, -124, -121, -118, -115, -112, -109, -106, -103, -100, -97, -94,
   -90, -87, -84, -81, -78, -75, -72, -69, -66, -63, -59, -56, -53, -50, -47, -44, -41, -38, -34, -31, -28, -25, -22, -19,
   -16, -13, -9, -6, -3
};

#elif defined(DDS_TABLE_LARGE)

// Large SineTable, 1024 values +/-127
#define ACCUMULATOR_BIT_SHIFT (ACCUMULATOR_BITS-10) // How many bits to keep from the accumulator to look up in this table
#define DDS_LOOKUPVALUE_BITS 8
static const int8_t ddsSineTable[1024] PROGMEM = {
  0, 0, 1, 2, 3, 3, 4, 5, 6, 7, 7, 8, 9, 10, 10, 11, 12, 13, 13, 14, 15, 16, 17, 17, 18, 19, 20, 20, 21, 22, 23, 24, 
  24, 25, 26, 27, 27, 28, 29, 30, 30, 31, 32, 33, 33, 34, 35, 36, 36, 37, 38, 39, 39, 40, 41, 42, 42, 43, 44, 44, 45, 46, 47, 47, 
  48, 49, 50, 50, 51, 52, 52, 53, 54, 55, 55, 56, 57, 57, 58, 59, 59, 60, 61, 61, 62, 63, 63, 64, 65, 65, 66, 67, 67, 68, 69, 69, 
  70, 71, 71, 72, 73, 73, 74, 75, 75, 76, 76, 77, 78, 78, 79, 79, 80, 81, 81, 82, 82, 83, 84, 84, 85, 85, 86, 87, 87, 88, 88, 89, 
  89, 90, 90, 91, 91, 92, 93, 93, 94, 94, 95, 95, 96, 96, 97, 97, 98, 98, 99, 99, 100, 100, 101, 101, 102, 102, 102, 103, 103, 104, 104, 105, 
  105, 106, 106, 106, 107, 107, 108, 108, 108, 109, 109, 110, 110, 110, 111, 111, 112, 112, 112, 113, 113, 113, 114, 114, 114, 115, 115, 115, 116, 116, 116, 117, 
  117, 117, 117, 118, 118, 118, 119, 119, 119, 119, 120, 120, 120, 120, 121, 121, 121, 121, 121, 122, 122, 122, 122, 123, 123, 123, 123, 123, 123, 124, 124, 124, 
  124, 124, 124, 124, 125, 125, 125, 125, 125, 125, 125, 125, 126, 126, 126, 126, 126, 126, 126, 126, 126, 126, 126, 126, 126, 126, 126, 126, 126, 126, 126, 126, 
  127, 126, 126, 126, 126, 126, 126, 126, 126, 126, 126, 126, 126, 126, 126, 126, 126, 126, 126, 126, 126, 125, 125, 125, 125, 125, 125, 125, 125, 124, 124, 124, 
  124, 124, 124, 124, 123, 123, 123, 123, 123, 123, 122, 122, 122, 122, 121, 121, 121, 121, 121, 120, 120, 120, 120, 119, 119, 119, 119, 118, 118, 118, 117, 117, 
  117, 117, 116, 116, 116, 115, 115, 115, 114, 114, 114, 113, 113, 113, 112, 112, 112, 111, 111, 110, 110, 110, 109, 109, 108, 108, 108, 107, 107, 106, 106, 106, 
  105, 105, 104, 104, 103, 103, 102, 102, 102, 101, 101, 100, 100, 99, 99, 98, 98, 97, 97, 96, 96, 95, 95, 94, 94, 93, 93, 92, 91, 91, 90, 90, 
  89, 89, 88, 88, 87, 87, 86, 85, 85, 84, 84, 83, 82, 82, 81, 81, 80, 79, 79, 78, 78, 77, 76, 76, 75, 75, 74, 73, 73, 72, 71, 71, 
  70, 69, 69, 68, 67, 67, 66, 65, 65, 64, 63, 63, 62, 61, 61, 60, 59, 59, 58, 57, 57, 56, 55, 55, 54, 53, 52, 52, 51, 50, 50, 49, 
  48, 47, 47, 46, 45, 44, 44, 43, 42, 42, 41, 40, 39, 39, 38, 37, 36, 36, 35, 34, 33, 33, 32, 31, 30, 30, 29, 28, 27, 27, 26, 25, 
  24, 24, 23, 22, 21, 20, 20, 19, 18, 17, 17, 16, 15, 14, 13, 13, 12, 11, 10, 10, 9, 8, 7, 7, 6, 5, 4, 3, 3, 2, 1, 0, 
  0, 0, -1, -2, -3, -3, -4, -5, -6, -7, -7, -8, -9, -10, -10, -11, -12, -13, -13, -14, -15, -16, -17, -17, -18, -19, -20, -20, -21, -22, -23, -24, 
  -24, -25, -26, -27, -27, -28, -29, -30, -30, -31, -32, -33, -33, -34, -35, -36, -36, -37, -38, -39, -39, -40, -41, -42, -42, -43, -44, -44, -45, -46, -47, -47, 
  -48, -49, -50, -50, -51, -52, -52, -53, -54, -55, -55, -56, -57, -57, -58, -59, -59, -60, -61, -61, -62, -63, -63, -64, -65, -65, -66, -67, -67, -68, -69, -69, 
  -70, -71, -71, -72, -73, -73, -74, -75, -75, -76, -76, -77, -78, -78, -79, -79, -80, -81, -81, -82, -82, -83, -84, -84, -85, -85, -86, -87, -87, -88, -88, -89, 
  -89, -90, -90, -91, -91, -92, -93, -93, -94, -94, -95, -95, -96, -96, -97, -97, -98, -98, -99, -99, -100, -100, -101, -101, -102, -102, -102, -103, -103, -104, -104, -105, 
  -105, -106, -106, -106, -107, -107, -108, -108, -108, -109, -109, -110, -110, -110, -111, -111, -112, -112, -112, -113, -113, -113, -114, -114, -114, -115, -115, -115, -116, -116, -116, -117, 
  -117, -117, -117, -118, -118, -118, -119, -119, -119, -119, -120, -120, -120, -120, -121, -121, -121, -121, -121, -122, -122, -122, -122, -123, -123, -123, -123, -123, -123, -124, -124, -124, 
  -124, -124, -124, -124, -125, -125, -125, -125, -125, -125, -125, -125, -126, -126, -126, -126, -126, -126, -126, -126, -126, -126, -126, -126, -126, -126, -126, -126, -126, -126, -126, -126, 
  -127, -126, -126, -126, -126, -126, -126, -126, -126, -126, -126, -126, -126, -126, -126, -126, -126, -126, -126, -126, -126, -125, -125, -125, -125, -125, -125, -125, -125, -124, -124, -124, 
  -124, -124, -124, -124, -123, -123, -123, -123, -123, -123, -122, -122, -122, -122, -121, -121, -121, -121, -121, -120, -120, -120, -120, -119, -119, -119, -119, -118, -118, -118, -117, -117, 
  -117, -117, -116, -116, -116, -115, -115, -115, -114, -114, -114, -113, -113, -113, -112, -112, -112, -111, -111, -110, -110, -110, -109, -109, -108, -108, -108, -107, -107, -106, -106, -106, 
  -105, -105, -104, -104, -103, -103, -102, -102, -102, -101, -101, -100, -100, -99, -99, -98, -98, -97, -97, -96, -96, -95, -95, -94, -94, -93, -93, -92, -91, -91, -90, -90, 
  -89, -89, -88, -88, -87, -87, -86, -85, -85, -84, -84, -83, -82, -82, -81, -81, -80, -79, -79, -78, -78, -77, -76, -76, -75, -75, -74, -73, -73, -72, -71, -71, 
  -70, -69, -69, -68, -67, -67, -66, -65, -65, -64, -63, -63, -62, -61, -61, -60, -59, -59, -58, -57, -57, -56, -55, -55, -54, -53, -52, -52, -51, -50, -50, -49, 
  -48, -47, -47, -46, -45, -44, -44, -43, -42, -42, -41, -40, -39, -39, -38, -37, -36, -36, -35, -34, -33, -33, -32, -31, -30, -30, -29, -28, -27, -27, -26, -25, 
  -24, -24, -23, -22, -21, -20, -20, -19, -18, -17, -17, -16, -15, -14, -13, -13, -12, -11, -10, -10, -9, -8, -7, -7, -6, -5, -4, -3, -3, -2, -1, 0
};

#else

// Standard SineTable, 256 values +/-127
#define ACCUMULATOR_BIT_SHIFT (ACCUMULATOR_BITS-8)
#define DDS_LOOKUPVALUE_BITS 8
static const int8_t ddsSineTable[256] PROGMEM = {0, 3, 6, 9, 12, 16, 19, 22, 25, 28, 31, 34, 37, 40, 43, 46, 49, 51, 54,
   57, 60, 63, 65, 68, 71, 73, 76, 78, 81, 83, 85, 88, 90, 92, 94, 96, 98, 100, 102, 104, 106, 107, 109, 111, 112, 113,
   115,  116, 117, 118, 120, 121, 122, 122, 123, 124, 125, 125, 126, 126, 126, 127, 127, 127, 127, 127, 127, 127, 126, 126,
   126, 125, 125, 124, 123, 122, 122, 121, 120, 118, 117, 116, 115, 113, 112, 111, 109, 107, 106, 104, 102, 100, 98, 96,
   94, 92, 90, 88, 85, 83, 81, 78, 76, 73, 71, 68, 65, 63, 60, 57, 54, 51, 49, 46, 43, 40, 37, 34, 31, 28, 25, 22, 19, 16,
   12, 9, 6, 3, 0, -3, -6, -9, -12, -16, -19, -22, -25, -28, -31, -34, -37, -40, -43, -46, -49, -51, -54, -57, -60, -63,
   -65, -68, -71, -73, -76, -78, -81, -83, -85, -88, -90, -92, -94, -96, -98, -100, -102, -104, -106, -107, -109, -111,
   -112, -113, -115, -116, -117, -118, -120, -121, -122, -122, -123, -124, -125, -125, -126, -126, -126, -127, -127, -127,
   -127, -127, -127, -127, -126, -126, -126, -125, -125, -124, -123, -122, -122, -121, -120, -118, -117, -116, -115, -113,
   -112, -111, -109, -107, -106, -104, -102, -100, -98, -96, -94, -92, -90, -88, -85, -83, -81, -78, -76, -73, -71, -68,
   -65, -63, -60, -57, -54, -51, -49, -46, -43, -40, -37, -34, -31, -28, -25, -22, -19, -16, -12, -9, -6, -3 
};

#endif /* DDS_TABLE_LARGE, DDS_TABLE_10BIT */

class DDS {
public:
  DDS(): refclk(DDS_REFCLK_DEFAULT), refclkOffset(DDS_REFCLK_OFFSET),
    accumulator(0), running(false),
    timeLimited(false), tickDuration(0), amplitude(255)
    {};

  // Start all of the timers needed
  void start();
  // Is the DDS presently producing a tone?
  const bool isRunning() { return running; };
  // Stop the DDS timers
  void stop();
  
  // Start and stop the PWM output
  void on() {
    timeLimited = false;
    running = true;
  }
  // Provide a duration in ms for the tone
  void on(unsigned short duration) {
    // Duration in ticks from milliseconds is:
    // t = (1/refclk)
    tickDuration = (unsigned long)((unsigned long)duration * (unsigned long)refclk) / 1000;
    timeLimited = true;
    running = true;
  }
  void off() {
    running = false;
  }
  
  // Generate a tone for a specific amount of time
  void play(unsigned short freq, unsigned short duration) {
    setFrequency(freq);
    on(duration);
  }
  // Blocking version
  void playWait(unsigned short freq, unsigned short duration) {
    play(freq, duration);
    delay(duration);
  }
  
  // Use these to get some calculated values for specific frequencies
  // or to get the current frequency stepping rate.
  ddsAccumulator_t calcFrequency(unsigned short freq);
  ddsAccumulator_t getPhaseAdvance() { return stepRate; };
  
  // Our maximum clock isn't very high, so our highest
  // frequency supported will fit in a short.
  void setFrequency(unsigned short freq) { stepRate = calcFrequency(freq); };
  void setPrecalcFrequency(ddsAccumulator_t freq) { stepRate = freq; };
  
  // Handle phase shifts
  void setPhaseDeg(int16_t degrees);
  void changePhaseDeg(int16_t degrees);
  
  // Adjustable reference clock. This shoud be done before the timers are
  // started, or they will need to be restarted. Frequencies will need to
  // be set again to use the new clock.
  void setReferenceClock(unsigned long ref) {
    refclk = ref;
  }
  unsigned long getReferenceClock() {
    return refclk;
  }

  void setReferenceOffset(int16_t offset) {
    refclkOffset = offset;
  }
  int16_t getReferenceOffset() {
    return refclkOffset;
  }
  
  ddsComparitor_t getDutyCycle();

  // Set a scaling factor. To keep things quick, this is a power of 2 value.
  // Set it with 0 for lowest (which will be off), 8 is highest.
  void setAmplitude(unsigned char amp) {
    amplitude = amp;
  }
  
  // This is the function called by the ADC_vect ISR to produce the tones
  void clockTick();
  
private:
  volatile bool running;
  volatile unsigned long tickDuration;
  volatile bool timeLimited;
  volatile unsigned char amplitude;
  volatile ddsAccumulator_t accumulator;
  volatile ddsAccumulator_t stepRate;
  ddsAccumulator_t refclk;
  int16_t refclkOffset;
  //static _DDS *sDDS;
};

#endif /* _DDS_H_ */