forked from M-Labs/artiq
coredevice: adf5355: more general PLL parameters calculation
Signed-off-by: Etienne Wodey <wodey@iqo.uni-hannover.de>
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@ -474,6 +474,18 @@ class ADF5355:
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return int32(r)
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@portable
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def gcd(a, b):
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while b:
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a, b = b, a % b
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return a
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@portable
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def split_msb_lsb_28b(v):
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return int32((v >> 14) & 0x3FFF), int32(v & 0x3FFF)
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@portable
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def calculate_pll(f_vco: TInt64, f_pfd: TInt64):
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"""
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@ -489,20 +501,21 @@ def calculate_pll(f_vco: TInt64, f_pfd: TInt64):
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f_vco = int64(f_vco)
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# integral part
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n = int32(f_vco / f_pfd)
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r = f_vco / f_pfd - n
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n, r = int32(f_vco // f_pfd), f_vco % f_pfd
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# main fractional part
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frac1 = int32(ADF5355_MODULUS1 * r)
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r = r * ADF5355_MODULUS1 - frac1
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r *= ADF5355_MODULUS1
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frac1, frac2 = int32(r // f_pfd), r % f_pfd
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# auxiliary fractional part
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# FIXME: calculate optimal MOD2
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mod2 = ADF5355_MAX_MODULUS2
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frac2 = int32(r * mod2)
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mod2 = f_pfd
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# split frac2, mod2
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frac2_msb, frac2_lsb = (frac2 >> 14) & 0x3FFF, frac2 & 0x3FFF
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mod2_msb, mod2_lsb = (mod2 >> 14) & 0x3FFF, mod2 & 0x3FFF
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while mod2 > ADF5355_MAX_MODULUS2:
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mod2 >>= 1
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frac2 >>= 1
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return n, frac1, (frac2_msb, frac2_lsb), (mod2_msb, mod2_lsb)
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gcd_div = gcd(frac2, mod2)
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mod2 //= gcd_div
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frac2 //= gcd_div
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return n, frac1, split_msb_lsb_28b(frac2), split_msb_lsb_28b(mod2)
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