Started following some tutorial on att85 usi. Downloaded example code from make avr book.

Make AVR Examples/Chapter13_Advanced-PWM-Tricks/dds_saw15/generateWavetables.py

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+## This file generates headers with lookup tables for various waveforms
+## Add your own.
+
+import math
+
+def phaseSteps(maxPhase, length=256):
+    steps = range(0, length) 
+    steps = [1.0*x/length * 2.0*math.pi * (maxPhase/360.0) for x in steps]
+    return(steps)
+
+def scaleAndRound(data, scale=255, signedInt=True):
+    data = [0.0+x-min(data) for x in data]
+    data = [1.0*x/max(data)*scale for x in data]
+    data = [int(round(x)) for x in data]
+    if signedInt:
+        data = [x-(scale+1)/2 for x in data]
+    return(data)
+
+def makeSin(maxPhase, length=256):
+    sinus = [math.sin(x) for x in phaseSteps(maxPhase, length)]
+    return(sinus)
+
+def prettyPrint(data, perLine = 8):
+    outString = ""
+    for i in range(len(data) / perLine):
+        strings = [str(x) for x in data[perLine*i:(perLine*i+perLine)]]
+        outString += "\t" + ", ".join(strings) + ",\n"
+    outString = outString[:-2] + "\n" # drop the final comma
+    return(outString)
+
+def writeHeader(fileName, dataName, data, signedInt=True):
+    outfile = open(fileName, "w")
+    if signedInt:
+        outfile.write("int8_t {}[{:d}] = {{ \n".format(dataName, len(data)))
+    else:
+        outfile.write("uint8_t {}[{:d}] = {{ \n".format(dataName, len(data)))
+    outfile.write(prettyPrint(data))
+    outfile.write("};\n")
+    outfile.close()
+
+def bandlimitedSawtooth(maxPhase, numberPartials, length=256):
+    wave = [0]*length
+    sign = 1.0
+    for k in range(1, numberPartials+1):
+        phases = phaseSteps(maxPhase*k, length)
+        for i in range(length):
+            wave[i] += sign * math.sin(phases[i]) / k
+        sign = sign * -1
+    return(wave)
+
+def bandlimitedSquare(maxPhase, numberPartials, length=256):
+    wave = [0]*length
+    for k in range(1, numberPartials*2, 2):
+        phases = phaseSteps(maxPhase*k, length)
+        for i in range(length):
+            wave[i] +=  math.sin(phases[i]) / k
+    return(wave)
+
+def bandlimitedTriangle(maxPhase, numberPartials, length=256):
+    wave = [0]*length
+    sign = 1.0
+    for k in range(1, numberPartials*2, 2):
+        phases = phaseSteps(maxPhase*k, length)
+        for i in range(length):
+            wave[i] += sign * math.sin(phases[i]) / k**2
+        sign = sign * -1
+    return(wave)
+
+
+
+if __name__ == "__main__":
+    
+    ## Full-waves, full 256 bytes, 0-255 range
+    writeHeader("fullSine.h", 'fullSine', scaleAndRound(makeSin(360)))
+
+    triangleWave = range(0,64)
+    triangleWave.extend(range(64, -64, -1))
+    triangleWave.extend(range(-64, 0, 1))
+    triangleWave = scaleAndRound(triangleWave)
+    writeHeader("fullTriangle.h", 'fullTriangle', triangleWave)
+
+    for numberFrequencies in [3,7,15]:
+        saw = scaleAndRound(bandlimitedSawtooth(360, numberFrequencies))
+        writeHeader("fullSaw{}.h".format(numberFrequencies), 
+                    'fullSaw{}'.format(numberFrequencies), saw)
+        tri = scaleAndRound(bandlimitedTriangle(360, numberFrequencies))
+        writeHeader("fullTri{}.h".format(numberFrequencies), 
+                    'fullTri{}'.format(numberFrequencies), tri)
+        square = scaleAndRound(bandlimitedSquare(360, numberFrequencies))
+        writeHeader("fullSquare{}.h".format(numberFrequencies), 
+                    'fullSquare{}'.format(numberFrequencies), square)
+
+    ## Note that if you define / use too many different waveforms, 
+    ## and you don't store them in PROGMEM in your AVR C routines,
+    ## you might run the chip out of RAM, which causes strange and
+    ## nearly impossible-to-diagnose glitches.
+    
+    ## So here we're breaking each waveform up into its own include file.
+    ## There are ways of storing them all in program memory, and we'll
+    ##  see examples of that in later chapters.
+