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dvisampler: software controlled phase detector
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Sebastien Bourdeauducq committed Mar 20, 2013
1 parent 28cb970 commit 0a14c37
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Showing 4 changed files with 86 additions and 59 deletions.
4 changes: 2 additions & 2 deletions build.py
View file
Expand Up @@ -46,10 +46,10 @@ def main():
NET "{dviclk0}" TNM_NET = "GRPdviclk0";
NET "{dviclk0}" CLOCK_DEDICATED_ROUTE = FALSE;
TIMESPEC "TSdviclk0" = PERIOD "GRPdviclk0" 22 ns HIGH 50%;
TIMESPEC "TSdviclk0" = PERIOD "GRPdviclk0" 26.7 ns HIGH 50%;
NET "{dviclk1}" TNM_NET = "GRPdviclk1";
NET "{dviclk1}" CLOCK_DEDICATED_ROUTE = FALSE;
TIMESPEC "TSdviclk1" = PERIOD "GRPdviclk1" 22 ns HIGH 50%;
TIMESPEC "TSdviclk1" = PERIOD "GRPdviclk1" 26.7 ns HIGH 50%;
""",
clk50=soc.crg.clk50_pad,
phy_rx_clk=soc.crg.eth_rx_clk_pad,
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4 changes: 2 additions & 2 deletions milkymist/dvisampler/__init__.py
View file
Expand Up @@ -7,7 +7,7 @@
from milkymist.dvisampler.datacapture import DataCapture

class DVISampler(Module, AutoReg):
def __init__(self, inversions="", debug_data_capture=True):
def __init__(self, inversions=""):
self.submodules.edid = EDID()
self.sda = self.edid.sda
self.scl = self.edid.scl
Expand All @@ -17,7 +17,7 @@ def __init__(self, inversions="", debug_data_capture=True):

for datan in "012":
name = "data" + str(datan)
cap = DataCapture(8, debug_data_capture)
cap = DataCapture(8)
setattr(self.submodules, name + "_cap", cap)
if datan in inversions:
name += "_n"
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9 changes: 8 additions & 1 deletion milkymist/dvisampler/clocking.py
View file
Expand Up @@ -15,6 +15,7 @@ def __init__(self):
self.serdesstrobe = Signal()
self.clock_domains._cd_pix = ClockDomain()
self.clock_domains._cd_pix5x = ClockDomain()
self.clock_domains._cd_pix10x = ClockDomain()
self.clock_domains._cd_pix20x = ClockDomain()

###
Expand All @@ -24,18 +25,22 @@ def __init__(self):
pll_clk0 = Signal()
pll_clk1 = Signal()
pll_clk2 = Signal()
pll_clk3 = Signal()
self.specials += Instance("PLL_BASE",
Instance.Parameter("CLKIN_PERIOD", 22.0),
Instance.Parameter("CLKIN_PERIOD", 26.7),
Instance.Parameter("CLKFBOUT_MULT", 20),
Instance.Parameter("CLKOUT0_DIVIDE", 1), # pix20x
Instance.Parameter("CLKOUT1_DIVIDE", 4), # pix5x
Instance.Parameter("CLKOUT2_DIVIDE", 20), # pix
Instance.Parameter("CLKOUT3_DIVIDE", 2), # pix10x
Instance.Parameter("COMPENSATION", "INTERNAL"),

Instance.Output("CLKFBOUT", clkfbout),
# WARNING: Do not touch the order of those clocks, or PAR fails.
Instance.Output("CLKOUT0", pll_clk0),
Instance.Output("CLKOUT1", pll_clk1),
Instance.Output("CLKOUT2", pll_clk2),
Instance.Output("CLKOUT3", pll_clk3),
Instance.Output("LOCKED", pll_locked),
Instance.Input("CLKFBIN", clkfbout),
Instance.Input("CLKIN", self.clkin),
Expand All @@ -56,6 +61,8 @@ def __init__(self):
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 += Instance("BUFG",
Instance.Input("I", pll_clk3), Instance.Output("O", self._cd_pix10x.clk))
self.specials += MultiReg(locked_async, self.locked, "sys")
self.comb += self._r_locked.field.w.eq(self.locked)

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128 changes: 74 additions & 54 deletions milkymist/dvisampler/datacapture.py
View file
Expand Up @@ -5,34 +5,40 @@
from migen.bank.description import *

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

if debug:
self._r_current_tap = RegisterField(8, READ_ONLY, WRITE_ONLY)
self._r_dly_ctl = RegisterRaw(4)
self._r_dly_busy = RegisterField(1, READ_ONLY, WRITE_ONLY)
self._r_phase = RegisterField(2, READ_ONLY, WRITE_ONLY)
self._r_phase_reset = RegisterRaw()

###

# IO
pad_delayed = Signal()
delay_inc = Signal()
delay_ce = Signal()
delay_cal = Signal()
delay_rst = Signal()
delay_busy = Signal()
self.specials += Instance("IODELAY2",
Instance.Parameter("DELAY_SRC", "IDATAIN"),
Instance.Parameter("IDELAY_TYPE", "VARIABLE_FROM_ZERO"),
Instance.Parameter("IDELAY_TYPE", "VARIABLE_FROM_HALF_MAX"),
Instance.Parameter("COUNTER_WRAPAROUND", "STAY_AT_LIMIT"),
Instance.Parameter("DATA_RATE", "SDR"),
Instance.Input("IDATAIN", self.pad),
Instance.Output("DATAOUT", pad_delayed),
Instance.Input("CLK", ClockSignal("pix5x")),
Instance.Input("IOCLK0", ClockSignal("pix10x")),
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("CAL", delay_cal),
Instance.Input("RST", delay_rst),
Instance.Output("BUSY", delay_busy),
Instance.Input("T", 1)
)

Expand All @@ -57,23 +63,19 @@ def __init__(self, ntbits, debug=False):
Instance.Input("RST", 0)
)

# Transition counter
transitions = Signal(ntbits)
lateness = Signal((ntbits + 1, True))
pulse_inc = Signal()
pulse_dec = Signal()
# Phase detector
lateness = Signal(ntbits, reset=2**(ntbits - 1))
too_late = Signal()
too_early = Signal()
reset_lateness = Signal()
self.comb += [
too_late.eq(lateness == (2**ntbits - 1)),
too_early.eq(lateness == 0)
]
self.sync.pix5x += [
pulse_inc.eq(0),
pulse_dec.eq(0),
If(transitions == 2**ntbits - 1,
If(lateness[ntbits],
pulse_inc.eq(1)
).Else(
pulse_dec.eq(1)
),
lateness.eq(0),
transitions.eq(0)
).Elif(self.d0 != self.d1,
If(reset_lateness,
lateness.eq(2**(ntbits - 1))
).Elif(~delay_busy & ~too_late & ~too_early & (self.d0 != self.d1),
If(self.d0,
# 1 -----> 0
# d0p
Expand All @@ -90,39 +92,57 @@ def __init__(self, ntbits, debug=False):
).Else(
lateness.eq(lateness - 1)
)
),
transitions.eq(transitions + 1)
)
)
]

# Delay control
self.submodules.delay_done = PulseSynchronizer("pix5x", "sys")
delay_pending = Signal()
self.sync.pix5x += [
self.delay_done.i.eq(0),
If(~delay_pending,
If(delay_cal | delay_ce, delay_pending.eq(1))
).Else(
If(~delay_busy,
self.delay_done.i.eq(1),
delay_pending.eq(0)
)
)
]

# 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.submodules.do_delay_cal = PulseSynchronizer("sys", "pix5x")
self.submodules.do_delay_rst = PulseSynchronizer("sys", "pix5x")
self.submodules.do_delay_inc = PulseSynchronizer("sys", "pix5x")
self.submodules.do_delay_dec = PulseSynchronizer("sys", "pix5x")
self.comb += [
delay_ce.eq(delay_init | pulse_inc | pulse_dec),
delay_inc.eq(delay_init | pulse_inc)
delay_cal.eq(self.do_delay_cal.o),
delay_rst.eq(self.do_delay_rst.o),
delay_inc.eq(self.do_delay_inc.o),
delay_ce.eq(self.do_delay_inc.o | self.do_delay_dec.o),
]

# Debug
if debug:
# 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)
)
sys_delay_pending = Signal()
self.sync += [
If(self.do_delay_cal.i | self.do_delay_inc.i | self.do_delay_dec.i,
sys_delay_pending.eq(1)
).Elif(self.delay_done.o,
sys_delay_pending.eq(0)
)
]

self.comb += [
self.do_delay_cal.i.eq(self._r_dly_ctl.re & self._r_dly_ctl.r[0]),
self.do_delay_rst.i.eq(self._r_dly_ctl.re & self._r_dly_ctl.r[1]),
self.do_delay_inc.i.eq(self._r_dly_ctl.re & self._r_dly_ctl.r[2]),
self.do_delay_dec.i.eq(self._r_dly_ctl.re & self._r_dly_ctl.r[3]),
self._r_dly_busy.field.w.eq(sys_delay_pending)
]

# Phase detector control
self.specials += MultiReg(Cat(too_late, too_early), self._r_phase.field.w)
self.submodules.do_reset_lateness = PulseSynchronizer("sys", "pix5x")
self.comb += [
reset_lateness.eq(self.do_reset_lateness.o),
self.do_reset_lateness.i.eq(self._r_phase_reset.re)
]

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