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sayma_amc: fix JDCGPattern data for 1Gsps

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Harry Ho 2020-12-15 17:56:05 +08:00 committed by Sébastien Bourdeauducq
parent 400af2c582
commit d74cd24d89
1 changed files with 13 additions and 5 deletions
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18
artiq/gateware/targets/sayma_amc.py
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@ -224,15 +224,23 @@ class JDCGPattern(Module, AutoCSR):
samples[0][i][:-4].eq(0x7ff if i % 2 else 0x800) samples[0][i][:-4].eq(0x7ff if i % 2 else 0x800)
] ]
# ch1: 50 MHz # ch1: 50 MHz
# - Formulae:
# target cosine wave frequency: f = 50e6
# DAC sampling frequency: fs = 1000e6
# number of samples per coarse RTIO period: P = 8
# number of samples needed per wave period: M = (1/f) / (1/fs)) = 20
# number of repeating samples needed: N = LCM(P, M) = 40
# number of RTIO periods needed for repeating: k = N/P = 5
# discretized value of the wave: y[i] = cos(i/M * 2pi)
from math import pi, cos from math import pi, cos
data = [int(round(cos(i/24*2*pi)*((1 << 15) - 1))) data = [int(round(cos(i/20*2*pi)*((1 << 15) - 1)))
for i in range(24)] for i in range(40)]
k = Signal(2) k = Signal(max=5)
self.sync.rtio += If(k == 2, k.eq(0)).Else(k.eq(k + 1)) self.sync.rtio += If(k == 4, k.eq(0)).Else(k.eq(k + 1))
self.comb += [ self.comb += [
Case(k, { Case(k, {
i: [samples[1][j].eq(data[i*8 + j]) for j in range(8)] i: [samples[1][j].eq(data[i*8 + j]) for j in range(8)]
for i in range(3) for i in range(5)
}) })
] ]
# ch2: ch0, ch3: ch1 # ch2: ch0, ch3: ch1