diff --git a/tb/lasmicon/lasmicon_df.py b/tb/lasmicon/lasmicon_df.py
new file mode 100644
index 000000000..054e1b660
--- /dev/null
+++ b/tb/lasmicon/lasmicon_df.py
@@ -0,0 +1,43 @@
+from migen.fhdl.std import *
+from migen.bus import lasmibus
+from migen.actorlib import dma_lasmi
+from migen.sim.generic import Simulator, TopLevel, Proxy
+
+from milkymist.lasmicon import *
+
+from common import sdram_phy, sdram_geom, sdram_timing, DFILogger
+
+class TB(Module):
+	def __init__(self):
+		self.submodules.ctler = LASMIcon(sdram_phy, sdram_geom, sdram_timing)
+		# FIXME: remove dummy master
+		self.submodules.xbar = lasmibus.Crossbar([self.ctler.lasmic], 2, self.ctler.nrowbits)
+		self.submodules.logger = DFILogger(self.ctler.dfi)
+		self.submodules.writer = dma_lasmi.Writer(self.xbar.masters[0])
+
+		self.comb += self.writer.address_data.stb.eq(1)
+		pl = self.writer.address_data.payload
+		pl.a.reset = 255
+		pl.d.reset = pl.a.reset*2
+		self.sync += If(self.writer.address_data.ack,
+			pl.a.eq(pl.a + 1),
+			pl.d.eq(pl.d + 2)
+		)
+		self.open_row = None
+
+	def do_simulation(self, s):
+		dfip = Proxy(s, self.ctler.dfi)
+		for p in dfip.phases:
+			if p.ras_n and not p.cas_n and not p.we_n: # write
+				d = dfip.phases[0].wrdata | (dfip.phases[1].wrdata << 64)
+				print(d)
+				if d != p.address//2 + p.bank*512 + self.open_row*2048:
+					print("**** ERROR ****")
+			elif not p.ras_n and p.cas_n and p.we_n: # activate
+				self.open_row = p.address
+
+def main():
+	sim = Simulator(TB(), TopLevel("my.vcd"))
+	sim.run(3500)
+
+main()