diff --git a/litex_boards/community/platforms/ecp5_evn.py b/litex_boards/community/platforms/ecp5_evn.py
index ddf5cdc..61db93d 100644
--- a/litex_boards/community/platforms/ecp5_evn.py
+++ b/litex_boards/community/platforms/ecp5_evn.py
@@ -1,8 +1,6 @@
 # This file is Copyright (c) 2019 Arnaud Durand <arnaud.durand@unifr.ch>
 # License: BSD
 
-import warnings
-
 from litex.build.generic_platform import *
 from litex.build.lattice import LatticePlatform
 from litex.build.lattice.programmer import LatticeProgrammer
@@ -33,10 +31,6 @@ _io = [
     ("user_dip_btn", 8, Pins("A16"), IOStandard("LVCMOS25")),
 
     ("serial", 0,
-        Subsignal("rx", Pins("P18"), IOStandard("LVCMOS33")),
-        Subsignal("tx", Pins("N20"), IOStandard("LVCMOS33")),
-    ),
-    ("serial", 1,
         Subsignal("rx", Pins("P2"), IOStandard("LVCMOS33")),
         Subsignal("tx", Pins("P3"), IOStandard("LVCMOS33")),
     ),
@@ -47,6 +41,7 @@ _io = [
         IOStandard("LVDS")
     ),
     ("ext_clk50", 0, Pins("B11"), IOStandard("LVCMOS33")),
+    ("ext_clk50_en", 0, Pins("C11"), IOStandard("LVCMOS33")),
 ]
 
 # Connectors ---------------------------------------------------------------------------------------
@@ -117,16 +112,18 @@ _connectors = [
 
 class Platform(LatticePlatform):
     default_clk_name = "clk12"
-    default_clk_period = 83.33
+    default_clk_period = 1e9/12e6
 
     def __init__(self, **kwargs):
         LatticePlatform.__init__(self, "LFE5UM5G-85F-8BG381", _io, _connectors, **kwargs)
 
     def request(self, *args, **kwargs):
         if "serial" in args:
-            warnings.warn("two 0 Ω resistors shoud be populated on R34 and R35")
+            print("two 0 Ω resistors shoud be populated on R34 and R35 and "
+            "the FT2232H should be configured to UART with virtual COM on "
+            "port B")
         if "ext_clk50" in args:
-            warnings.warn("an oscillator must be populated on X5")
+            print("an oscillator must be populated on X5")
             
         return LatticePlatform.request(self, *args, **kwargs)
 
diff --git a/litex_boards/community/targets/ecp5_evn.py b/litex_boards/community/targets/ecp5_evn.py
index f548627..bd365b4 100755
--- a/litex_boards/community/targets/ecp5_evn.py
+++ b/litex_boards/community/targets/ecp5_evn.py
@@ -4,7 +4,6 @@
 # License: BSD
 
 import argparse
-from warnings import warn
 
 from migen import *
 from migen.genlib.resetsync import AsyncResetSynchronizer
@@ -18,7 +17,7 @@ from litex.soc.integration.builder import *
 # CRG ----------------------------------------------------------------------------------------------
 
 class _CRG(Module):
-    def __init__(self, platform, sys_clk_freq):
+    def __init__(self, platform, sys_clk_freq, x5_clk_freq):
         self.clock_domains.cd_sys = ClockDomain()
 
         # # #
@@ -26,29 +25,33 @@ class _CRG(Module):
         self.cd_sys.clk.attr.add("keep")
 
         # clk / rst
-        clk12 = platform.request("clk12")
+        clk = clk12 = platform.request("clk12")
         rst_n = platform.request("rst_n")
-        platform.add_period_constraint(clk12, 83.33)
+        platform.add_period_constraint(clk12, 1e9/12e6)
+        if x5_clk_freq is not None:
+            clk = clk50 = platform.request("ext_clk50")
+            self.comb += platform.request("ext_clk50_en").eq(1)
+            platform.add_period_constraint(clk50, 1e9/x5_clk_freq)
 
         # pll
-        # self.submodules.pll = pll = ECP5PLL()
-        # self.comb += pll.reset.eq(~rst_n)
-        # pll.register_clkin(clk12, 12e6)
-        # pll.create_clkout(self.cd_sys, sys_clk_freq)
-        # self.specials += AsyncResetSynchronizer(self.cd_sys, ~rst_n)
-        self.comb += self.cd_sys.clk.eq(clk12)
+        self.submodules.pll = pll = ECP5PLL()
+        self.comb += pll.reset.eq(~rst_n)
+        pll.register_clkin(clk, x5_clk_freq or 12e6)
+        pll.create_clkout(self.cd_sys, sys_clk_freq)
+        self.specials += AsyncResetSynchronizer(self.cd_sys, ~rst_n)
+        self.comb += self.cd_sys.clk.eq(clk)
 
 # BaseSoC ------------------------------------------------------------------------------------------
 
 class BaseSoC(SoCCore):
-    def __init__(self, sys_clk_freq=int(12e6), toolchain="diamond", **kwargs):
+    def __init__(self, sys_clk_freq=int(50e6), x5_clk_freq=None, toolchain="diamond", **kwargs):
         platform = ecp5_evn.Platform(toolchain=toolchain)
         SoCCore.__init__(self, platform, clk_freq=sys_clk_freq,
                           integrated_rom_size=0x8000,
                           **kwargs)
 
         # crg
-        crg = _CRG(platform, sys_clk_freq)
+        crg = _CRG(platform, sys_clk_freq, x5_clk_freq)
         self.submodules.crg = crg
 
 # Build --------------------------------------------------------------------------------------------
@@ -59,12 +62,17 @@ def main():
         help='gateware toolchain to use, diamond (default) or  trellis')
     builder_args(parser)
     soc_core_args(parser)
-    parser.add_argument("--sys-clk-freq", default=12e6,
+    parser.add_argument("--sys-clk-freq", default=50e6,
                         help="system clock frequency (default=50MHz)")
+    parser.add_argument("--x5-clk-freq", type=int,
+                        help="use X5 oscillator as system clock at the specified frequency")
     args = parser.parse_args()
 
     cls = BaseSoC
-    soc = cls(toolchain=args.toolchain, sys_clk_freq=int(float(args.sys_clk_freq)), **soc_core_argdict(args))
+    soc = cls(toolchain=args.toolchain,
+        sys_clk_freq=int(float(args.sys_clk_freq)),
+        x5_clk_freq=args.x5_clk_freq,
+        **soc_core_argdict(args))
     builder = Builder(soc, **builder_argdict(args))
     builder.build()