align master/slave pair

single_serdes_loopback.py

@@ -24,7 +24,9 @@ class SingleSerDesLoopBack(Module):
         
         self.submodules.tx = SingleLineTX()
         self.submodules.rx = SingleLineRX()
-        self.submodules.phase_reader = PhaseReader()
+        self.submodules.bitslip_reader = BitSlipReader()
+        self.submodules.slave_aligner = SlaveAligner()
+        self.submodules.post_align_reader = BitSlipReader()
         # self.submodules.delay_optimizer = DelayOptimizer()
 
         # The actual channel
@@ -51,17 +53,21 @@ class SingleSerDesLoopBack(Module):
         # Route deserializer to phase_reader & the delay tap optimizer
         self.comb += [
             # Start the reader initially
-            self.phase_reader.start.eq(1),
+            self.bitslip_reader.start.eq(1),
             # Delay tap optimizer will start after the reader is done
             # self.delay_optimizer.start.eq(0),
+            self.slave_aligner.start.eq(0),
+            self.post_align_reader.start.eq(0),
 
             # RXDATA for both reader and optimzer
-            self.phase_reader.loopback_rxdata.eq(self.rx.rxdata),
+            self.bitslip_reader.loopback_rxdata.eq(self.rx.rxdata),
             # TODO: Reconnet
             # self.delay_optimizer.loopback_rxdata.eq(self.rx.rxdata),
+            self.slave_aligner.loopback_rxdata.eq(self.rx.rxdata),
+            self.post_align_reader.loopback_rxdata.eq(self.rx.rxdata),
 
             # Delay tap value
-            self.phase_reader.delay_tap.eq(self.rx.cnt_out),
+            # self.phase_reader.delay_tap.eq(self.rx.cnt_out),
             # TODO: Reconnet
             # self.delay_optimizer.delay_tap.eq(self.rx.cnt_out),
 
@@ -73,54 +79,104 @@ class SingleSerDesLoopBack(Module):
             # ).Else(
             #     self.rx.ce.eq(self.phase_reader.inc_en),
             # )
-            self.rx.ce.eq(self.phase_reader.inc_en),
+            # self.rx.ce.eq(self.phase_reader.inc_en),
+            self.rx.master_bitslip.eq(
+                self.bitslip_reader.bitslip |
+                self.slave_aligner.master_bitslip |
+                self.post_align_reader.bitslip
+            ),
+            self.rx.slave_bitslip.eq(
+                self.bitslip_reader.bitslip |
+                self.slave_aligner.slave_bitslip |
+                self.post_align_reader.bitslip
+            ),
         ]
 
         # Show measured result on UART
         delay_tap = Signal(6)
+        bitslip_count = Signal(3)
+        post_align_bitslip_count = Signal(3)
 
         fsm = FSM(reset_state="WAIT_DONE")
         self.submodules += fsm
 
         fsm.act("WAIT_DONE",
-            If(self.phase_reader.done,
+            If(self.bitslip_reader.done,
                 NextState("WRITE_UPPER"),
             ),
         )
 
         fsm.act("WRITE_UPPER",
             # Exist state if all results are sent
-            If(delay_tap == 32,
+            If(bitslip_count == 5,
-                NextState("TERMINATE"),
+                NextState("FIND_OPT_DELAY"),
             ).Elif(self.tx_fifo.writable,
                 self.tx_fifo.we.eq(1),
-                self.tx_fifo.din.eq(self.phase_reader.data_result[delay_tap][8:]),
+                self.tx_fifo.din.eq(self.bitslip_reader.data_result[bitslip_count][8:]),
                 NextState("WRITE_LOWER"),
             ),
         )
 
         fsm.act("WRITE_LOWER",
             self.tx_fifo.we.eq(1),
-            self.tx_fifo.din.eq(self.phase_reader.data_result[delay_tap][:8]),
+            self.tx_fifo.din.eq(self.bitslip_reader.data_result[bitslip_count][:8]),
-            NextValue(delay_tap, delay_tap + 1),
+            NextValue(bitslip_count, bitslip_count + 1),
             NextState("WRITE_UPPER"),
         )
 
-        # fsm.act("FIND_OPT_DELAY",
+        fsm.act("FIND_OPT_DELAY",
-        #     self.delay_optimizer.start.eq(1),
+            self.slave_aligner.start.eq(1),
-        #     self.rx.ce.eq(self.delay_optimizer.inc_en),
+            # self.rx.ce.eq(self.delay_optimizer.inc_en),
-        #     If(self.delay_optimizer.done,
+            If(self.slave_aligner.done,
-        #         NextState("WRITE_OPT"),
+                NextState("WRITE_DONE_UPPER"),
-        #     ).Else(
+            ).Else(
-        #         NextState("FIND_OPT_DELAY")
+                NextState("FIND_OPT_DELAY")
-        #     )
+            )
-        # )
+        )
 
-        # fsm.act("WRITE_OPT",
+        fsm.act("WRITE_DONE_UPPER",
-        #     self.tx_fifo.we.eq(1),
+            self.post_align_reader.start.eq(1),
-        #     self.tx_fifo.din.eq(self.delay_optimizer.opt_delay_tap),
+            If(self.tx_fifo.writable,
-        #     NextState("TERMINATE")
+                self.tx_fifo.we.eq(1),
-        # )
+                self.tx_fifo.din.eq(0xFF),
+                NextState("WRITE_DONE_LOWER")
+            )
+        )
+
+        fsm.act("WRITE_DONE_LOWER",
+            self.post_align_reader.start.eq(1),
+            If(self.tx_fifo.writable,
+                self.tx_fifo.we.eq(1),
+                self.tx_fifo.din.eq(0xFF),
+                NextState("REREAD_BITSLIP")
+            )
+        )
+
+        fsm.act("REREAD_BITSLIP",
+            If(self.post_align_reader.done,
+                NextState("REWRITE_UPPER"),
+            ).Else(
+                NextState("REREAD_BITSLIP"),
+            ),
+        )
+
+        fsm.act("REWRITE_UPPER",
+            # Exist state if all results are sent
+            If(post_align_bitslip_count == 5,
+                NextState("TERMINATE"),
+            ).Elif(self.tx_fifo.writable,
+                self.tx_fifo.we.eq(1),
+                self.tx_fifo.din.eq(self.post_align_reader.data_result[post_align_bitslip_count][8:]),
+                NextState("REWRITE_LOWER"),
+            ),
+        )
+
+        fsm.act("REWRITE_LOWER",
+            self.tx_fifo.we.eq(1),
+            self.tx_fifo.din.eq(self.post_align_reader.data_result[post_align_bitslip_count][:8]),
+            NextValue(post_align_bitslip_count, post_align_bitslip_count + 1),
+            NextState("REWRITE_UPPER"),
+        )
 
         fsm.act("TERMINATE",
             NextState("TERMINATE"),

sync_serdes.py

@@ -35,6 +35,8 @@ class SingleLineRX(Module):
         self.ce = Signal()
         self.cnt_out = Signal(5)
         self.opt_delay = Signal(5)
+        self.master_bitslip = Signal()
+        self.slave_bitslip = Signal()
 
         ser_in = Signal()
         shifts = Signal(2)
@@ -59,7 +61,7 @@ class SingleLineRX(Module):
                 o_SHIFTOUT1=shifts[0],
                 o_SHIFTOUT2=shifts[1],
                 i_DDLY=ser_in,
-                i_BITSLIP=0,
+                i_BITSLIP=self.master_bitslip,
                 i_CLK=ClockSignal("rx_sys5x"),
                 i_CLKB=~ClockSignal("rx_sys5x"),
                 i_CE1=1,
@@ -77,7 +79,7 @@ class SingleLineRX(Module):
                 o_Q3=self.rxdata[1],
                 o_Q4=self.rxdata[0],
                 # i_DDLY=ser_in,
-                i_BITSLIP=0,
+                i_BITSLIP=self.slave_bitslip,
                 i_CLK=ClockSignal("rx_sys5x"),
                 i_CLKB=~ClockSignal("rx_sys5x"),
                 i_CE1=1,
@@ -189,6 +191,129 @@ class BitSlipReader(Module):
         )
 
 
+class SlaveAligner(Module):
+    def __init__(self):
+        # IN
+        self.loopback_rxdata = Signal(10)
+        self.start = Signal()
+
+        # Wait for stabilization after bitslip
+        self.submodules.stab_timer = WaitTimer(511)
+
+        # OUT
+        self.done = Signal()
+        self.master_bitslip = Signal()
+        self.slave_bitslip = Signal()
+        # self.data_result = Array(Signal(10) for _ in range(5))
+
+        self.slip_count = Signal(3)
+
+        check_odd = Signal()
+        check_even = Signal()
+
+        fsm = FSM(reset_state="WAIT_START")
+        self.submodules += fsm
+
+        fsm.act("WAIT_START",
+            If(self.start,
+                NextState("WAIT_TIMER"),
+            ).Else(
+                NextState("WAIT_START"),
+            )
+        )
+
+        fsm.act("WAIT_TIMER",
+            self.stab_timer.wait.eq(1),
+            If(self.stab_timer.done,
+                NextState("SAMPLE"),
+            )
+        )
+
+        fsm.act("SAMPLE",
+            # Wait is reset now
+            # Explicit assignment is unnecessary, as combinatorial statement
+            # falls back to he default value when not driven
+
+            # Detect the last 2 bits
+            # If signal is received, detune the master bitslip if necessary
+            If(self.loopback_rxdata[0] | self.loopback_rxdata[1],
+                NextValue(check_odd, self.loopback_rxdata[1]),
+                NextValue(check_even, self.loopback_rxdata[0]),
+                NextState("CHECK_MASTER_BITSLIP"),
+            ).Else(
+                NextValue(self.slip_count, self.slip_count + 1),
+                NextState("HIGH_BITSLIP_FIRST"),
+            )
+        )
+
+        # Pulsing BITSLIP alternate between 1 right shift and 3 left shifts
+        # We are trying to figure out which 2-bits are the slave copying from
+        # Hence, we only want shifts by 2. Pulsing twice does exactly that.
+        fsm.act("HIGH_BITSLIP_FIRST",
+            self.master_bitslip.eq(1),
+            self.slave_bitslip.eq(1),
+            NextState("LOW_BITSLIP"),
+        )
+
+        fsm.act("LOW_BITSLIP",
+            # bitslip signal is auto-reset
+            NextState("HIGH_BITSLIP_SECOND"),
+        )
+
+        fsm.act("HIGH_BITSLIP_SECOND",
+            self.master_bitslip.eq(1),
+            self.slave_bitslip.eq(1),
+            If(self.slip_count == 5,
+                NextState("TERMINATE"),
+            ).Else(
+                NextState("WAIT_TIMER"),
+            )
+        )
+
+        odd_master_rxdata = self.loopback_rxdata[3::2]
+        even_master_rxdata = self.loopback_rxdata[2::2]
+
+        # Alternatively, we align the master with the slave
+        fsm.act("CHECK_MASTER_BITSLIP",
+            # At any point if the odd and/or even bits from the master reads 0
+            # It implies the detuning is completed
+            NextState("TERMINATE"),
+            If(check_odd & (odd_master_rxdata != 0),
+                NextState("MASTER_HIGH_BITSLIP_FIRST"),
+            ),
+            If(check_even & (even_master_rxdata != 0),
+                NextState("MASTER_HIGH_BITSLIP_FIRST"),
+            ),
+        )
+
+        fsm.act("MASTER_HIGH_BITSLIP_FIRST",
+            self.master_bitslip.eq(1),
+            NextState("MASTER_LOW_BITSLIP"),
+        )
+
+        fsm.act("MASTER_LOW_BITSLIP",
+            # bitslip signal is auto-reset
+            NextState("MASTER_HIGH_BITSLIP_SECOND"),
+        )
+
+        fsm.act("MASTER_HIGH_BITSLIP_SECOND",
+            self.master_bitslip.eq(1),
+            NextState("MASTER_WAIT_TIMER"),
+        )
+
+        fsm.act("MASTER_WAIT_TIMER",
+            self.stab_timer.wait.eq(1),
+            If(self.stab_timer.done,
+                NextState("CHECK_MASTER_BITSLIP"),
+            )
+        )
+
+        fsm.act("TERMINATE",
+            self.done.eq(1),
+            NextState("TERMINATE"),
+        )
+
+
 
 class PhaseReader(Module):
     def __init__(self):

test_aligner.py

@@ -1,5 +1,5 @@
 from migen import *
-from sync_serdes import PhaseReader, DelayOptimizer, BitSlipReader
+from sync_serdes import PhaseReader, DelayOptimizer, BitSlipReader, SlaveAligner
 import random
 
 
@@ -131,6 +131,73 @@ def bitslip_reader_tb(dut, rxdata_list):
     yield
 
 
+def bitslip_aligner_tb(dut, rxdata_list, adjust_list):
+    # Start the module
+    yield dut.start.eq(1)
+    assert (yield dut.stab_timer.wait) == 0
+
+    for i in range(len(rxdata_list)):
+        yield dut.loopback_rxdata.eq(rxdata_list[i])
+        yield
+        yield
+        assert (yield dut.stab_timer.wait) == 1
+
+        # Wait until the timer runs out
+        while (yield dut.stab_timer.done) == 0:
+            yield
+
+        # There will not be unnecessary pulses
+        if i == (len(rxdata_list) - 1):
+            break
+
+        # Keep yielding until the DUT gives BITSLIP signal
+        while (((yield dut.master_bitslip) == 0) and ((yield dut.slave_bitslip) == 0)):
+            yield
+        
+        # There will be 2 BITSLIP pulses
+        # Both BITSLIP pulses should last for 1 cycle
+        assert (yield dut.master_bitslip) == 1
+        assert (yield dut.slave_bitslip) == 1
+        yield
+        assert (yield dut.master_bitslip) == 0
+        assert (yield dut.slave_bitslip) == 0
+        yield
+        assert (yield dut.master_bitslip) == 1
+        assert (yield dut.slave_bitslip) == 1
+        yield
+        assert (yield dut.master_bitslip) == 0
+        assert (yield dut.slave_bitslip) == 0
+    
+    # Skip ahead 2 cycles for state transitions
+    yield
+    yield
+    
+    for i in range(len(adjust_list)):
+        # Eventually the master bitslip signal will be pulled up
+        while (yield dut.master_bitslip) == 0:
+            yield
+        
+        assert (yield dut.master_bitslip) == 1
+        assert (yield dut.slave_bitslip) == 0
+        yield
+        assert (yield dut.master_bitslip) == 0
+        assert (yield dut.slave_bitslip) == 0
+        yield
+        assert (yield dut.master_bitslip) == 1
+        assert (yield dut.slave_bitslip) == 0
+        yield 
+        assert (yield dut.master_bitslip) == 0
+        assert (yield dut.slave_bitslip) == 0
+
+        # Give the new rxdata
+        yield dut.loopback_rxdata.eq(adjust_list[i])
+        while (yield dut.stab_timer.done) == 0:
+            yield
+
+    yield
+    yield
+    assert (yield dut.done) == 1
+
 # # Random testing for delay reader
 # for _ in range(32):
 #     rxdata_list = [ random.getrandbits(10) for _ in range(32) ]
@@ -191,8 +258,75 @@ def bitslip_reader_tb(dut, rxdata_list):
 #     vcd_name="delay_opt.vcd"
 # )
 
-# Random test for bitslip reader
+# # Random test for bitslip reader
-for _ in range(32):
+# for _ in range(32):
-    rxdata_list = [ random.getrandbits(10) for _ in range(5) ]
+#     rxdata_list = [ random.getrandbits(10) for _ in range(5) ]
-    dut = BitSlipReader()
+#     dut = BitSlipReader()
-    run_simulation(dut, bitslip_reader_tb(dut, rxdata_list), vcd_name="bitslip_reader.vcd")
+#     run_simulation(dut, bitslip_reader_tb(dut, rxdata_list), vcd_name="bitslip_reader.vcd")
+
+# Test for bitslip alignment
+def generate_aligner_tb_list(mocked_pair, start_pair):
+    print("Mocked pair", str(mocked_pair))
+    print("Start pair", str(start_pair))
+    double_bit_pattern = bool(random.randint(0, 1))
+    pulsed_indices = [ random.randint(0, 9) ]
+    print("Pulsed indices", str(pulsed_indices))
+
+    if double_bit_pattern:
+        pulsed_indices.append((pulsed_indices[0] + 1) % 10)
+
+    def generate_rxdata(pair_shift):
+        mocked_data = 0
+
+        rxdata = 0
+        for index in pulsed_indices:
+            rxdata |= (1 << ((index + 2*pair_shift) % 10))
+
+        mocking_mask = (1 << (2*mocked_pair)) | (1 << ((2*mocked_pair) + 1))
+        mocked_data = ((rxdata & mocking_mask) >> (2*mocked_pair))
+
+        # Wipe out the 2 lsb
+        rxdata &= 0x3FC
+        # Copy the mocked data to the 2 lsb
+        rxdata |= mocked_data
+        return mocked_data, rxdata
+    
+    rxdata_list = []
+    for i in range(5):
+        mocked_data, rxdata = generate_rxdata((start_pair + i) % 5)
+        rxdata_list.append(rxdata)
+        if mocked_data:
+            break
+
+    print("Mocked data", str(mocked_data))
+    
+    def is_mocking(original):
+        if original == 0:
+            return False
+        if (original & 0b11) == mocked_data:
+            return True
+        return is_mocking(original >> 2)
+
+    adjust_list = []
+    master_rxdata = rxdata_list[-1] & 0x3FC
+    if mocked_data and is_mocking(master_rxdata):
+        # Keep adding shifted variant to the adjust_list
+        # Until the 2 lsb is not mocking other pairs
+        while True:
+            master_rxdata <<= 2
+            master_rxdata &= 0x3FF
+            adjust_list.append(master_rxdata | mocked_data)
+            if not is_mocking(master_rxdata):
+                break
+    
+    return rxdata_list, adjust_list
+
+for mocked_pair in range(5):
+    for start_pair in range(5):
+        for _ in range(12):
+            rxdata_list, adjust_list = generate_aligner_tb_list(mocked_pair, start_pair)
+            print(rxdata_list)
+            print(adjust_list)
+            dut = SlaveAligner()
+            run_simulation(dut, bitslip_aligner_tb(dut, rxdata_list, adjust_list), vcd_name="bitslip_aligner.vcd")
+            print(mocked_pair, start_pair)