artiq-zynq/src/gateware/ddmtd.py

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from migen import *
from migen.genlib.cdc import PulseSynchronizer, MultiReg
from misoc.interconnect.csr import *
class DDMTDSampler(Module):
def __init__(self, cd_ref, main_clk_se):
self.ref_beating = Signal()
self.main_beating = Signal()
# # #
2024-04-25 11:02:19 +08:00
ref_clk = Signal()
self.specials +=[
# ISERDESE2 can only be driven from fabric via IDELAYE2 (see UG471)
Instance("IDELAYE2",
p_DELAY_SRC="DATAIN",
p_HIGH_PERFORMANCE_MODE="TRUE",
p_REFCLK_FREQUENCY=208.3, # REFCLK frequency from IDELAYCTRL
p_IDELAY_VALUE=0,
i_DATAIN=cd_ref.clk,
o_DATAOUT=ref_clk
),
Instance("ISERDESE2",
p_IOBDELAY="IFD", # use DDLY as input
p_DATA_RATE="SDR",
p_DATA_WIDTH=2, # min is 2
p_NUM_CE=1,
i_DDLY=ref_clk,
i_CE1=1,
i_CLK=ClockSignal("helper"),
i_CLKDIV=ClockSignal("helper"),
o_Q1=self.ref_beating
),
Instance("ISERDESE2",
p_DATA_RATE="SDR",
p_DATA_WIDTH=2, # min is 2
p_NUM_CE=1,
i_D=main_clk_se,
i_CE1=1,
i_CLK=ClockSignal("helper"),
i_CLKDIV=ClockSignal("helper"),
o_Q1=self.main_beating,
),
]
class DDMTDDeglitcherFirstEdge(Module):
def __init__(self, input_signal, blind_period=400):
self.detect = Signal()
rising = Signal()
input_signal_r = Signal()
# # #
self.sync.helper += [
input_signal_r.eq(input_signal),
rising.eq(input_signal & ~input_signal_r)
]
blind_counter = Signal(max=blind_period)
self.sync.helper += [
If(blind_counter != 0, blind_counter.eq(blind_counter - 1)),
If(input_signal_r, blind_counter.eq(blind_period - 1)),
self.detect.eq(rising & (blind_counter == 0))
]
class DDMTD(Module):
def __init__(self, counter, input_signal):
# in helper clock domain
self.h_tag = Signal(len(counter))
self.h_tag_update = Signal()
# # #
deglitcher = DDMTDDeglitcherFirstEdge(input_signal)
self.submodules += deglitcher
self.sync.helper += [
self.h_tag_update.eq(0),
If(deglitcher.detect,
self.h_tag_update.eq(1),
self.h_tag.eq(counter)
)
]