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dvisampler: use pix5x as IODELAY clock
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Sebastien Bourdeauducq committed Mar 18, 2013
1 parent 48aae9b commit 5126f61
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Showing 3 changed files with 39 additions and 49 deletions.
3 changes: 1 addition & 2 deletions milkymist/dvisampler/__init__.py
View file
Expand Up @@ -25,6 +25,5 @@ def __init__(self, inversions="", debug_data_capture=True):
setattr(self, name, s)
self.comb += [
cap.pad.eq(s),
cap.serdesstrobe.eq(self.clocking.serdesstrobe),
cap.delay_rst.eq(~self.clocking.locked)
cap.serdesstrobe.eq(self.clocking.serdesstrobe)
]
9 changes: 5 additions & 4 deletions milkymist/dvisampler/clocking.py
View file
Expand Up @@ -8,7 +8,7 @@ class Clocking(Module, AutoReg):
def __init__(self):
self.clkin = Signal()

self._r_pll_reset = RegisterField(reset=1)
self._r_pll_reset = RegisterField()
self._r_locked = RegisterField(1, READ_ONLY, WRITE_ONLY)

self.locked = Signal()
Expand Down Expand Up @@ -46,15 +46,16 @@ def __init__(self):
self.specials += Instance("BUFPLL",
Instance.Parameter("DIVIDE", 4),
Instance.Input("PLLIN", pll_clk0),
Instance.ClockPort("GCLK", "pix5x"),
Instance.Input("GCLK", ClockSignal("pix5x")),
Instance.Input("LOCKED", pll_locked),
Instance.Output("IOCLK", self._cd_pix20x.clk),
Instance.Output("LOCK", locked_async),
Instance.Output("SERDESSTROBE", self.serdesstrobe)
)
self.specials += MultiReg(locked_async, self.locked, "sys")
self.comb += self._r_locked.field.w.eq(self.locked)
self.specials += Instance("BUFG",
Instance.Input("I", pll_clk1), Instance.Output("O", self._cd_pix5x.clk))
self.specials += Instance("BUFG",
Instance.Input("I", pll_clk2), Instance.Output("O", self._cd_pix.clk))
self.specials += MultiReg(locked_async, self.locked, "sys")
self.specials += MultiReg(~locked_async, self._cd_pix5x.rst, "pix5x")
self.comb += self._r_locked.field.w.eq(self.locked)
76 changes: 33 additions & 43 deletions milkymist/dvisampler/datacapture.py
View file
@@ -1,19 +1,17 @@
from migen.fhdl.structure import *
from migen.fhdl.module import Module
from migen.fhdl.specials import Instance
from migen.genlib.cdc import PulseSynchronizer
from migen.genlib.cdc import MultiReg, PulseSynchronizer
from migen.bank.description import *

class DataCapture(Module, AutoReg):
def __init__(self, ntbits, debug=False):
self.pad = Signal()
self.serdesstrobe = Signal()
self.delay_rst = Signal() # system clock domain
self.d0 = Signal() # pix5x clock domain
self.d1 = Signal() # pix5x clock domain

if debug:
self._r_delay_rst = RegisterRaw()
self._r_current_tap = RegisterField(8, READ_ONLY, WRITE_ONLY)

###
Expand All @@ -22,31 +20,21 @@ def __init__(self, ntbits, debug=False):
pad_delayed = Signal()
delay_inc = Signal()
delay_ce = Signal()
delay_rst = Signal()
delay_init = Signal()
self.specials += Instance("IODELAY2",
Instance.Parameter("DELAY_SRC", "IDATAIN"),
Instance.Parameter("IDELAY_TYPE", "VARIABLE_FROM_ZERO"),
Instance.Parameter("COUNTER_WRAPAROUND", "STAY_AT_LIMIT"),
Instance.Parameter("DATA_RATE", "SDR"),
Instance.Input("IDATAIN", self.pad),
Instance.Output("DATAOUT", pad_delayed),
Instance.Input("INC", delay_inc | delay_init),
Instance.Input("CE", delay_ce | delay_init),
Instance.Input("RST", delay_rst),
Instance.ClockPort("CLK"),
Instance.ClockPort("IOCLK0", "pix20x"),
Instance.Input("INC", delay_inc),
Instance.Input("CE", delay_ce),
Instance.Input("RST", ResetSignal("pix5x")),
Instance.Input("CLK", ClockSignal("pix5x")),
Instance.Input("IOCLK0", ClockSignal("pix20x")),
Instance.Input("CAL", 0),
Instance.Input("T", 1)
)
# initialize delay to 127 taps
delay_init_count = Signal(7, reset=127)
self.comb += delay_init.eq(delay_init_count != 0)
self.sync += If(delay_rst,
delay_init_count.eq(127)
).Elif(delay_init,
delay_init_count.eq(delay_init_count - 1)
)

d0p = Signal()
d1p = Signal()
Expand All @@ -62,8 +50,8 @@ def __init__(self, ntbits, debug=False):
Instance.Output("Q1", d1p),
Instance.Input("BITSLIP", 0),
Instance.Input("CE0", 1),
Instance.ClockPort("CLK0", "pix20x"),
Instance.ClockPort("CLKDIV", "pix5x"),
Instance.Input("CLK0", ClockSignal("pix20x")),
Instance.Input("CLKDIV", ClockSignal("pix5x")),
Instance.Input("D", pad_delayed),
Instance.Input("IOCE", self.serdesstrobe),
Instance.Input("RST", 0)
Expand Down Expand Up @@ -107,32 +95,34 @@ def __init__(self, ntbits, debug=False):
)
]

# Send delay update commands to system (IDELAY) clock domain
self.submodules.xf_inc = PulseSynchronizer("pix5x", "sys")
self.submodules.xf_dec = PulseSynchronizer("pix5x", "sys")
# Drive IODELAY controls
delay_init = Signal()
delay_init_count = Signal(7, reset=127)
self.comb += delay_init.eq(delay_init_count != 0)
self.sync.pix5x += If(delay_init, delay_init_count.eq(delay_init_count - 1))
self.comb += [
self.xf_inc.i.eq(pulse_inc),
delay_inc.eq(self.xf_inc.o),
self.xf_dec.i.eq(pulse_dec),
delay_ce.eq(self.xf_inc.o | self.xf_dec.o)
delay_ce.eq(delay_init | pulse_inc | pulse_dec),
delay_inc.eq(delay_init | pulse_inc)
]

# Debug
if debug:
self.comb += delay_rst.eq(self.delay_rst | self._r_delay_rst.re)
current_tap = self._r_current_tap.field.w
self.sync += If(delay_rst,
current_tap.eq(0)
).Elif(delay_ce,
If(delay_inc,
If(current_tap != 0xff,
current_tap.eq(current_tap + 1)
)
).Else(
If(current_tap != 0,
current_tap.eq(current_tap - 1)
)
# Transfer delay update commands to system clock domain
pix5x_reset_sys = Signal()
self.specials += MultiReg(ResetSignal("pix5x"), pix5x_reset_sys, "sys")
self.submodules.xf_inc = PulseSynchronizer("pix5x", "sys")
self.submodules.xf_dec = PulseSynchronizer("pix5x", "sys")
self.comb += [
self.xf_inc.i.eq(pulse_inc),
self.xf_dec.i.eq(pulse_dec)
]
# Update tap count in system clock domain
current_tap = Signal(8, reset=127)
self.comb += self._r_current_tap.field.w.eq(current_tap)
self.sync += If(pix5x_reset_sys,
current_tap.eq(127)
).Elif(self.xf_inc.o & (current_tap != 0xff),
current_tap.eq(current_tap + 1)
).Elif(self.xf_dec.o & (current_tap != 0),
current_tap.eq(current_tap - 1)
)
)
else:
self.comb += delay_rst.eq(self.delay_rst)

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