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wrpll: DDMTD sampler double latching

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This commit is contained in:
Sebastien Bourdeauducq 2020-01-22 19:16:26 +08:00
parent f4d8f77268
commit dee16edb78
1 changed files with 31 additions and 8 deletions
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39
artiq/gateware/drtio/wrpll/ddmtd.py
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@ -6,21 +6,34 @@ from misoc.interconnect.csr import *
class DDMTDSamplerExtFF(Module):
def __init__(self, ddmtd_inputs):
self.rec_clk = Signal()
self.main_xo = Signal()
# # #
# TODO: s/h timing at FPGA pads
if hasattr(ddmtd_inputs, "rec_clk"):
self.rec_clk = ddmtd_inputs.rec_clk
rec_clk_1 = ddmtd_inputs.rec_clk
else:
self.rec_clk = Signal()
rec_clk_1 = Signal()
self.specials += Instance("IBUFDS",
i_I=ddmtd_inputs.rec_clk_p, i_IB=ddmtd_inputs.rec_clk_n,
o_O=self.rec_clk)
o_O=rec_clk_1)
if hasattr(ddmtd_inputs, "main_xo"):
self.main_xo = ddmtd_inputs.main_xo
main_xo_1 = ddmtd_inputs.main_xo
else:
self.main_xo = Signal()
main_xo_1 = Signal()
self.specials += Instance("IBUFDS",
i_I=ddmtd_inputs.main_xo_p, i_IB=ddmtd_inputs.main_xo_n,
o_O=self.main_xo)
o_O=main_xo_1)
self.specials += [
Instance("FD", i_C=ClockSignal("helper"),
i_D=rec_clk_1, o_Q=self.rec_clk,
attr={("IOB", "TRUE")}),
Instance("FD", i_C=ClockSignal("helper"),
i_D=main_xo_1, o_Q=self.main_xo,
attr={("IOB", "TRUE")}),
]
class DDMTDSamplerGTP(Module):
@ -28,20 +41,30 @@ class DDMTDSamplerGTP(Module):
self.rec_clk = Signal()
self.main_xo = Signal()
# # #
# Getting the main XO signal from IBUFDS_GTE2 is problematic because
# the transceiver PLL craps out if an improper clock signal is applied,
# so we are disabling the buffer until the clock is stable.
main_xo_se = Signal()
rec_clk_1 = Signal()
main_xo_1 = Signal()
self.specials += [
Instance("IBUFDS",
i_I=main_xo_pads.p, i_IB=main_xo_pads.n,
o_O=main_xo_se),
Instance("FD", i_C=ClockSignal("helper"),
i_D=gtp.cd_rtio_rx0.clk, o_Q=self.rec_clk,
i_D=gtp.cd_rtio_rx0.clk, o_Q=rec_clk_1,
attr={("DONT_TOUCH", "TRUE")}),
Instance("FD", i_C=ClockSignal("helper"),
i_D=main_xo_se, o_Q=self.main_xo,
i_D=rec_clk_1, o_Q=self.rec_clk,
attr={("DONT_TOUCH", "TRUE")}),
Instance("FD", i_C=ClockSignal("helper"),
i_D=main_xo_se, o_Q=main_xo_1,
attr={("IOB", "TRUE")}),
Instance("FD", i_C=ClockSignal("helper"),
i_D=main_xo_1, o_Q=self.main_xo,
attr={("DONT_TOUCH", "TRUE")}),
]