diff --git a/soc/artiqlib/rtio/__init__.py b/soc/artiqlib/rtio/__init__.py
index 1f1b4f691..9c20b7171 100644
--- a/soc/artiqlib/rtio/__init__.py
+++ b/soc/artiqlib/rtio/__init__.py
@@ -1,111 +1,2 @@
-from migen.fhdl.std import *
-from migen.bank.description import *
-from migen.genlib.fifo import SyncFIFOBuffered
-from migen.genlib.cdc import MultiReg
-
-from types import SimpleNamespace
-
 from artiqlib.rtio import phy
-
-class RTIOBankO(Module):
-	def __init__(self, channels, counter_width, fine_ts_width, fifo_depth):
-		self.sel = Signal(max=len(channels))
-		self.timestamp = Signal(counter_width+fine_ts_width)
-		self.value = Signal()
-		self.writable = Signal()
-		self.we = Signal()
-		self.underflow = Signal()
-		self.level = Signal(bits_for(fifo_depth))
-
-		###
-
-		counter = Signal(counter_width)
-		self.sync += [
-			counter.eq(counter + 1),
-			If(self.we & self.writable,
-				If(self.timestamp[fine_ts_width:] < counter + 2, self.underflow.eq(1))
-			)
-		]
-
-		fifos = []
-		for n, channel in enumerate(channels):
-			fifo = SyncFIFOBuffered([
-				("timestamp", counter_width+fine_ts_width), ("value", 2)],
-				fifo_depth)
-			self.submodules += fifo
-			fifos.append(fifo)
-
-			# FIFO write
-			self.comb += [
-				fifo.din.timestamp.eq(self.timestamp),
-				fifo.din.value.eq(self.value),
-				fifo.we.eq(self.we & (self.sel == n))
-			]
-
-			# FIFO read
-			self.comb += [
-				channel.hit.eq(fifo.readable &
-					(fifo.dout.timestamp[fine_ts_width:] == counter)),
-				channel.value.eq(fifo.dout.value),
-				fifo.re.eq(channel.hit)
-			]
-			if fine_ts_width:
-				self.comb += channel.fine_ts.eq(fifo.dout.timestamp[:fine_ts_width])
-
-		selfifo = Array(fifos)[self.sel]
-		self.comb += self.writable.eq(selfifo.writable), self.level.eq(selfifo.level)
-
-class RTIO(Module, AutoCSR):
-	def __init__(self, phy, counter_width=32, ofifo_depth=8, ififo_depth=8):
-		# Extract info from PHY
-		if hasattr(phy.interface[0], "o_fine_ts"):
-			fine_ts_width = flen(channels[0].o_fine_ts)
-		else:
-			fine_ts_width = 0
-		oes = [padif.oe for padif in phy.interface if hasattr(padif, "oe")]
-
-		# Submodules
-		self.submodules.bank_o = InsertReset(RTIOBankO(
-			[SimpleNamespace(hit=padif.o_set_value,
-					value=padif.o_value,
-					fine_ts=getattr(padif, "o_fine_ts", None))
-				for padif in phy.interface],
-			counter_width, fine_ts_width, ofifo_depth))
-
-		# CSRs
-		self._r_reset = CSRStorage(reset=1)
-		self._r_chan_sel = CSRStorage(flen(self.bank_o.sel))
-		
-		self._r_oe = CSR()
-
-		self._r_o_timestamp = CSRStorage(counter_width+fine_ts_width)
-		self._r_o_value = CSRStorage()
-		self._r_o_writable = CSRStatus()
-		self._r_o_we = CSR()
-		self._r_o_underflow = CSRStatus()
-		self._r_o_level = CSRStatus(bits_for(ofifo_depth))
-
-		# OE
-		oes = []
-		for n, padif in enumerate(phy.interface):
-			if hasattr(padif, "oe"):
-				self.sync += \
-					If(self._r_oe.re & (self._r_chan_sel.storage == n),
-						padif.oe.eq(self._r_oe.r)
-					)
-				oes.append(padif.oe)
-			else:
-				oes.append(1)
-		self.comb += self._r_oe.w.eq(Array(oes)[self._r_chan_sel.storage])
-
-		# Output/Gate
-		self.comb += [
-			self.bank_o.reset.eq(self._r_reset.storage),
-			self.bank_o.sel.eq(self._r_chan_sel.storage),
-			self.bank_o.timestamp.eq(self._r_o_timestamp.storage),
-			self.bank_o.value.eq(self._r_o_value.storage),
-			self._r_o_writable.status.eq(self.bank_o.writable),
-			self.bank_o.we.eq(self._r_o_we.re),
-			self._r_o_underflow.status.eq(self.bank_o.underflow),
-			self._r_o_level.status.eq(self.bank_o.level)
-		]
+from artiqlib.rtio.core import RTIO
diff --git a/soc/artiqlib/rtio/core.py b/soc/artiqlib/rtio/core.py
new file mode 100644
index 000000000..79ab4b77d
--- /dev/null
+++ b/soc/artiqlib/rtio/core.py
@@ -0,0 +1,183 @@
+from migen.fhdl.std import *
+from migen.bank.description import *
+from migen.genlib.fifo import SyncFIFOBuffered
+from migen.genlib.cdc import MultiReg
+
+from artiqlib.rtio.rbus import get_fine_ts_width
+
+class _RTIOBankO(Module):
+	def __init__(self, rbus, counter_width, fine_ts_width, fifo_depth, counter_init):
+		self.sel = Signal(max=len(rbus))
+		self.timestamp = Signal(counter_width+fine_ts_width)
+		self.value = Signal(2)
+		self.writable = Signal()
+		self.we = Signal()
+		self.underflow = Signal()
+		self.level = Signal(bits_for(fifo_depth))
+
+		###
+
+		counter = Signal(counter_width, reset=counter_init)
+		self.sync += [
+			counter.eq(counter + 1),
+			If(self.we & self.writable,
+				If(self.timestamp[fine_ts_width:] < counter + 2, self.underflow.eq(1))
+			)
+		]
+
+		fifos = []
+		for n, chif in enumerate(rbus):
+			fifo = SyncFIFOBuffered([
+				("timestamp", counter_width+fine_ts_width), ("value", 2)],
+				fifo_depth)
+			self.submodules += fifo
+			fifos.append(fifo)
+
+			# FIFO write
+			self.comb += [
+				fifo.din.timestamp.eq(self.timestamp),
+				fifo.din.value.eq(self.value),
+				fifo.we.eq(self.we & (self.sel == n))
+			]
+
+			# FIFO read
+			self.comb += [
+				chif.o_stb.eq(fifo.readable &
+					(fifo.dout.timestamp[fine_ts_width:] == counter)),
+				chif.o_value.eq(fifo.dout.value),
+				fifo.re.eq(chif.o_stb)
+			]
+			if fine_ts_width:
+				self.comb += chif.o_fine_ts.eq(fifo.dout.timestamp[:fine_ts_width])
+
+		selfifo = Array(fifos)[self.sel]
+		self.comb += self.writable.eq(selfifo.writable), self.level.eq(selfifo.level)
+
+class _RTIOBankI(Module):
+	def __init__(self, rbus, counter_width, fine_ts_width, fifo_depth):
+		self.sel = Signal(max=len(rbus))
+		self.timestamp = Signal(counter_width+fine_ts_width)
+		self.value = Signal()
+		self.readable = Signal()
+		self.re = Signal()
+		self.overflow = Signal()
+
+		###
+
+		counter = Signal(counter_width)
+		self.sync += counter.eq(counter + 1)
+
+		timestamps = []
+		values = []
+		readables = []
+		overflows = []
+		for n, chif in enumerate(rbus):
+			if hasattr(chif, "oe"):
+				sensitivity = Signal(2)
+				self.sync += If(~chif.oe & chif.o_stb,
+					sensitivity.eq(chif.o_value))
+
+				fifo = SyncFIFOBuffered([
+					("timestamp", counter_width+fine_ts_width), ("value", 1)],
+					fifo_depth)
+				self.submodules += fifo
+				
+				# FIFO write
+				if fine_ts_width:
+					full_ts = Cat(chif.i_fine_ts, counter)
+				else:
+					full_ts = counter
+				self.comb += [
+					fifo.din.timestamp.eq(full_ts),
+					fifo.din.value.eq(chif.i_value),
+					fifo.we.eq(~chif.oe & chif.i_stb &
+						((chif.i_value & sensitivity[0]) | (~chif.i_value & sensitivity[1])))
+				]
+
+				# FIFO read
+				timestamps.append(fifo.dout.timestamp)
+				values.append(fifo.dout.value)
+				readables.append(fifo.readable)
+				self.comb += fifo.re.eq(self.re & (self.sel == n))
+				
+				overflow = Signal()
+				self.sync += If(fifo.we & ~fifo.writable, overflow.eq(1))
+				overflows.append(overflow)
+			else:
+				timestamps.append(0)
+				values.append(0)
+				readables.append(0)
+				overflows.append(0)
+
+		self.comb += [
+			self.timestamp.eq(Array(timestamps)[self.sel]),
+			self.value.eq(Array(values)[self.sel]),
+			self.readable.eq(Array(readables)[self.sel]),
+			self.overflow.eq(Array(overflows)[self.sel])
+		]
+
+class RTIO(Module, AutoCSR):
+	def __init__(self, phy, counter_width=32, ofifo_depth=8, ififo_depth=8):
+		fine_ts_width = get_fine_ts_width(phy.rbus)
+
+		# Submodules
+		self.submodules.bank_o = InsertReset(_RTIOBankO(phy.rbus,
+			counter_width, fine_ts_width, ofifo_depth,
+			phy.loopback_latency))
+		self.submodules.bank_i = InsertReset(_RTIOBankI(phy.rbus,
+			counter_width, fine_ts_width, ofifo_depth))
+
+		# CSRs
+		self._r_reset = CSRStorage(reset=1)
+		self._r_chan_sel = CSRStorage(flen(self.bank_o.sel))
+		
+		self._r_oe = CSR()
+
+		self._r_o_timestamp = CSRStorage(counter_width+fine_ts_width)
+		self._r_o_value = CSRStorage(2)
+		self._r_o_writable = CSRStatus()
+		self._r_o_we = CSR()
+		self._r_o_underflow = CSRStatus()
+		self._r_o_level = CSRStatus(bits_for(ofifo_depth))
+
+		self._r_i_timestamp = CSRStatus(counter_width+fine_ts_width)
+		self._r_i_value = CSRStatus()
+		self._r_i_readable = CSRStatus()
+		self._r_i_re = CSR()
+		self._r_i_overflow = CSRStatus()
+
+		# OE
+		oes = []
+		for n, chif in enumerate(phy.rbus):
+			if hasattr(chif, "oe"):
+				self.sync += \
+					If(self._r_oe.re & (self._r_chan_sel.storage == n),
+						chif.oe.eq(self._r_oe.r)
+					)
+				oes.append(chif.oe)
+			else:
+				oes.append(1)
+		self.comb += self._r_oe.w.eq(Array(oes)[self._r_chan_sel.storage])
+
+		# Output/Gate
+		self.comb += [
+			self.bank_o.reset.eq(self._r_reset.storage),
+			self.bank_o.sel.eq(self._r_chan_sel.storage),
+			self.bank_o.timestamp.eq(self._r_o_timestamp.storage),
+			self.bank_o.value.eq(self._r_o_value.storage),
+			self._r_o_writable.status.eq(self.bank_o.writable),
+			self.bank_o.we.eq(self._r_o_we.re),
+			self._r_o_underflow.status.eq(self.bank_o.underflow),
+			self._r_o_level.status.eq(self.bank_o.level)
+		]
+
+		# Input
+		self.comb += [
+			self.bank_i.reset.eq(self._r_reset.storage),
+			self.bank_i.sel.eq(self._r_chan_sel.storage),
+			self._r_i_timestamp.status.eq(self.bank_i.timestamp),
+			self._r_i_value.status.eq(self.bank_i.value),
+			self._r_i_readable.status.eq(self.bank_i.readable),
+			self.bank_i.re.eq(self._r_i_re.re),
+			self._r_i_overflow.status.eq(self.bank_i.overflow)
+		]
diff --git a/soc/artiqlib/rtio/phy.py b/soc/artiqlib/rtio/phy.py
index 4e7f1de78..1cdfa96ba 100644
--- a/soc/artiqlib/rtio/phy.py
+++ b/soc/artiqlib/rtio/phy.py
@@ -1,50 +1,29 @@
 from migen.fhdl.std import *
 from migen.genlib.cdc import MultiReg
-from migen.genlib.record import Record
 
-class PHYBase(Module):
-	def __init__(self, fine_ts_bits, pads, output_only_pads):
-		self.interface = []
-		
-		for pad in pads:
-			layout = [
-				("o_set_value", 1),
-				("o_value", 1)
-			]
-			if fine_ts_bits:
-				layout.append(("o_fine_ts", fine_ts_bits))
-			if pad not in output_only_pads:
-				layout += [
-					("oe", 1),
-					("i_detect", 1),
-					("i_value", 1)
-				]
-				if fine_ts_bits:
-					layout.append(("i_fine_ts", fine_ts_bits))
-			self.interface.append(Record(layout))
+from artiqlib.rtio.rbus import create_rbus
 
-class SimplePHY(PHYBase):
+class SimplePHY(Module):
 	def __init__(self, pads, output_only_pads=set()):
-		PHYBase.__init__(self, 0, pads, output_only_pads)
+		self.rbus = create_rbus(0, pads, output_only_pads)
+		self.loopback_latency = 3
 
-		for pad, padif in zip(pads, self.interface):
-			o_pad_d1 = Signal()
+		###
+
+		for pad, chif in zip(pads, self.rbus):
 			o_pad = Signal()
-			self.sync += [
-				If(padif.o_set_value, o_pad_d1.eq(padif.o_value)),
-				o_pad.eq(o_pad_d1)
-			]
+			self.sync += If(chif.o_stb, o_pad.eq(chif.o_value))
 			if pad in output_only_pads:
 				self.comb += pad.eq(o_pad)
 			else:
 				ts = TSTriple()
 				i_pad = Signal()
-				self.sync += ts.oe.eq(padif.oe)
+				self.sync += ts.oe.eq(chif.oe)
 				self.comb += ts.o.eq(o_pad)
 				self.specials += MultiReg(ts.i, i_pad), \
 					ts.get_tristate(pad)
 
 				i_pad_d = Signal()
 				self.sync += i_pad_d.eq(i_pad)
-				self.comb += padif.i_detect.eq(i_pad ^ i_pad_d), \
-					padif.i_value.eq(i_pad)
+				self.comb += chif.i_stb.eq(i_pad ^ i_pad_d), \
+					chif.i_value.eq(i_pad)
diff --git a/soc/artiqlib/rtio/rbus.py b/soc/artiqlib/rtio/rbus.py
new file mode 100644
index 000000000..47e739b7e
--- /dev/null
+++ b/soc/artiqlib/rtio/rbus.py
@@ -0,0 +1,28 @@
+from migen.fhdl.std import *
+from migen.genlib.record import Record
+
+def create_rbus(fine_ts_bits, pads, output_only_pads):
+	rbus = []
+	for pad in pads:
+		layout = [
+			("o_stb", 1),
+			("o_value", 2)
+		]
+		if fine_ts_bits:
+			layout.append(("o_fine_ts", fine_ts_bits))
+		if pad not in output_only_pads:
+			layout += [
+				("oe", 1),
+				("i_stb", 1),
+				("i_value", 1)
+			]
+			if fine_ts_bits:
+				layout.append(("i_fine_ts", fine_ts_bits))
+		rbus.append(Record(layout))
+	return rbus
+
+def get_fine_ts_width(rbus):
+	if hasattr(rbus[0], "o_fine_ts"):
+		return flen(rbus[0].o_fine_ts)
+	else:
+		return 0