diff --git a/src/main/scala/ee/hrzn/chryse/platform/ChryseTop.scala b/src/main/scala/ee/hrzn/chryse/platform/ChryseTop.scala
index a61517d..46b370d 100644
--- a/src/main/scala/ee/hrzn/chryse/platform/ChryseTop.scala
+++ b/src/main/scala/ee/hrzn/chryse/platform/ChryseTop.scala
@@ -2,6 +2,7 @@ package ee.hrzn.chryse.platform
 
 import chisel3._
 import chisel3.experimental.noPrefix
+import ee.hrzn.chryse.chisel.DirectionOf
 
 import scala.collection.mutable
 import scala.language.implicitConversions
@@ -16,6 +17,11 @@ trait ChryseTop extends RawModule {
       ConnectedResource(pin, None)
   }
 
+  protected def platformConnect(
+      name: String,
+      res: resource.ResourceData[_ <: Data],
+  ): Option[Data] = None
+
   protected def connectResources(
       platform: PlatformBoard[_ <: PlatformBoardResources],
       clock: Option[Clock],
@@ -41,20 +47,32 @@ trait ChryseTop extends RawModule {
           clock.get := noPrefix(IO(Input(Clock())).suggestName(name))
 
         case _ =>
-          if (platformConnect(name, res)) {
-            connected += name -> res.pinId.get
-          } else if (res.ioInst.isDefined) {
-            res.makeIoConnection()
-            connected += name -> res.pinId.get
+          val topIo: Option[Data] = platformConnect(name, res) match {
+            case Some(t) =>
+              connected += name -> res.pinId.get
+              Some(t)
+            case None =>
+              if (res.ioInst.isDefined) {
+                connected += name -> res.pinId.get
+                Some(res.makeIoConnection())
+              } else None
+          }
+          topIo match {
+            case None =>
+            case Some(t) =>
+              val port = IO(res.makeIo()).suggestName(name)
+              DirectionOf(port) match {
+                case SpecifiedDirection.Input =>
+                  t := port
+                case SpecifiedDirection.Output =>
+                  port := t
+                case dir =>
+                  throw new Exception(s"unhandled direction: $dir")
+              }
           }
       }
     }
 
     connected.to(Map)
   }
-
-  protected def platformConnect(
-      name: String,
-      res: resource.ResourceData[_ <: Data],
-  ): Boolean = false
 }
diff --git a/src/main/scala/ee/hrzn/chryse/platform/PlatformBoardResources.scala b/src/main/scala/ee/hrzn/chryse/platform/PlatformBoardResources.scala
index 8930f90..de7a6fd 100644
--- a/src/main/scala/ee/hrzn/chryse/platform/PlatformBoardResources.scala
+++ b/src/main/scala/ee/hrzn/chryse/platform/PlatformBoardResources.scala
@@ -1,12 +1,15 @@
 package ee.hrzn.chryse.platform
 
 import chisel3._
+import chisel3.experimental.Param
 import ee.hrzn.chryse.platform.resource.ResourceBase
 import ee.hrzn.chryse.platform.resource.ResourceData
 
 import scala.collection.mutable.ArrayBuffer
 
 abstract class PlatformBoardResources {
+  val defaultAttributes = Map[String, Param]()
+
   private[chryse] def setNames() =
     for { f <- this.getClass().getDeclaredFields() } {
       f.setAccessible(true)
diff --git a/src/main/scala/ee/hrzn/chryse/platform/ice40/ICE40Top.scala b/src/main/scala/ee/hrzn/chryse/platform/ice40/ICE40Top.scala
index cc03b96..30224bf 100644
--- a/src/main/scala/ee/hrzn/chryse/platform/ice40/ICE40Top.scala
+++ b/src/main/scala/ee/hrzn/chryse/platform/ice40/ICE40Top.scala
@@ -16,9 +16,24 @@ class ICE40Top[Top <: Module](
     genTop: => Top,
 ) extends RawModule
     with ChryseTop {
-  var lastPCF: Option[PCF] = None
+  override protected def platformConnect(
+      name: String,
+      res: resource.ResourceData[_ <: Data],
+  ): Option[Data] = {
+    if (name == "ubtn" && ubtn_reset.isDefined) {
+      if (res.ioInst.isDefined)
+        throw new Exception("ubtnReset requested but ubtn used in design")
 
-  // TODO (iCE40): SB_GBs between a lot more things.
+      // ubtn_reset.get := IO(res.makeIo()).suggestName("ubtn")
+      val topIo = Wire(res.makeIo())
+      ubtn_reset.get := topIo
+      return Some(topIo)
+    }
+
+    None
+  }
+
+  // TODO (iCE40): actually create IO buffers.
 
   private val clki = Wire(Clock())
 
@@ -58,22 +73,7 @@ class ICE40Top[Top <: Module](
   private val connectedResources =
     connectResources(platform, Some(clki))
 
-  override protected def platformConnect(
-      name: String,
-      res: resource.ResourceData[_ <: Data],
-  ): Boolean = {
-    if (name == "ubtn" && ubtn_reset.isDefined) {
-      if (res.ioInst.isDefined)
-        throw new Exception("ubtnReset requested but ubtn used in design")
-
-      ubtn_reset.get := IO(res.makeIo()).suggestName("ubtn")
-      return true
-    }
-
-    false
-  }
-
-  lastPCF = Some(
+  val lastPCF = Some(
     PCF(
       connectedResources
         .map { case (name, cr) => (name, cr.pin) }
diff --git a/src/main/scala/ee/hrzn/chryse/platform/ice40/IOStandard.scala b/src/main/scala/ee/hrzn/chryse/platform/ice40/IOStandard.scala
index 2be88ea..3f208f6 100644
--- a/src/main/scala/ee/hrzn/chryse/platform/ice40/IOStandard.scala
+++ b/src/main/scala/ee/hrzn/chryse/platform/ice40/IOStandard.scala
@@ -1,5 +1,6 @@
 package ee.hrzn.chryse.platform.ice40
 
 object IOStandard {
-  val LV_CMOS = "SB_LVCMOS"
+  val LVCMOS = "SB_LVCMOS"
+  val LVTTL  = "SB_LVTTL"
 }
diff --git a/src/main/scala/ee/hrzn/chryse/platform/ice40/IceBreakerPlatform.scala b/src/main/scala/ee/hrzn/chryse/platform/ice40/IceBreakerPlatform.scala
index 71643ae..24e1bec 100644
--- a/src/main/scala/ee/hrzn/chryse/platform/ice40/IceBreakerPlatform.scala
+++ b/src/main/scala/ee/hrzn/chryse/platform/ice40/IceBreakerPlatform.scala
@@ -1,6 +1,7 @@
 package ee.hrzn.chryse.platform.ice40
 
 import chisel3._
+import chisel3.experimental.Param
 import ee.hrzn.chryse.platform.PlatformBoard
 import ee.hrzn.chryse.platform.PlatformBoardResources
 import ee.hrzn.chryse.platform.resource
@@ -24,12 +25,16 @@ final case class IceBreakerPlatform(ubtnReset: Boolean = false)
 }
 
 class IceBreakerPlatformResources extends PlatformBoardResources {
-  // TODO: IO_STANDARD=SB_LVCMOS needs to be set on most SB_IOs.
+  override val defaultAttributes = Map("IO_STANDARD" -> IOStandard.LVCMOS)
+
   val clock = resource.ClockSource(12_000_000).onPin(35)
 
   val ubtn = resource.Button().inverted.onPin(10)
 
-  val uart = resource.UART().onPins(rx = 6, tx = 9)
+  val uart = resource
+    .UART()
+    .onPins(rx = 6, tx = 9)
+    .withAttributes("IO_STANDARD" -> IOStandard.LVTTL, "PULLUP" -> 1)
 
   val ledg = resource.LED().inverted.onPin(37)
   val ledr = resource.LED().inverted.onPin(11)
diff --git a/src/main/scala/ee/hrzn/chryse/platform/ice40/SB_GB_IO.scala b/src/main/scala/ee/hrzn/chryse/platform/ice40/SB_GB_IO.scala
index 2cb0797..e103f14 100644
--- a/src/main/scala/ee/hrzn/chryse/platform/ice40/SB_GB_IO.scala
+++ b/src/main/scala/ee/hrzn/chryse/platform/ice40/SB_GB_IO.scala
@@ -6,7 +6,7 @@ import chisel3.experimental.ExtModule
 class SB_GB_IO(pinType: Int = (PinType.PIN_INPUT | PinType.PIN_NO_OUTPUT))
     extends ExtModule(
       Map(
-        "IO_STANDARD" -> IOStandard.LV_CMOS,
+        "IO_STANDARD" -> IOStandard.LVCMOS,
         "PIN_TYPE"    -> pinType,
       ),
     ) {
diff --git a/src/main/scala/ee/hrzn/chryse/platform/ice40/SB_IO.scala b/src/main/scala/ee/hrzn/chryse/platform/ice40/SB_IO.scala
index 60743f4..92dd249 100644
--- a/src/main/scala/ee/hrzn/chryse/platform/ice40/SB_IO.scala
+++ b/src/main/scala/ee/hrzn/chryse/platform/ice40/SB_IO.scala
@@ -6,7 +6,7 @@ import chisel3.experimental.ExtModule
 
 class SB_IO(
     pinType: Int,
-    ioStandard: String = IOStandard.LV_CMOS,
+    ioStandard: String = IOStandard.LVCMOS,
     pullup: Boolean = false,
 ) extends ExtModule(
       Map(
diff --git a/src/main/scala/ee/hrzn/chryse/platform/resource/InOut.scala b/src/main/scala/ee/hrzn/chryse/platform/resource/InOut.scala
index 96712aa..df72976 100644
--- a/src/main/scala/ee/hrzn/chryse/platform/resource/InOut.scala
+++ b/src/main/scala/ee/hrzn/chryse/platform/resource/InOut.scala
@@ -1,6 +1,7 @@
 package ee.hrzn.chryse.platform.resource
 
 import chisel3._
+import chisel3.experimental.Param
 
 // TODO: it's an error to use both "i" and "o" (tristate is a different kettle
 // of fish entirely) — this'll currently throw an obscure Chisel error (since
@@ -20,6 +21,12 @@ class InOut extends ResourceBase with ResourceSinglePin {
     this
   }
 
+  def withAttributes(attribs: (String, Param)*): this.type = {
+    i.withAttributes(attribs: _*)
+    o.withAttributes(attribs: _*)
+    this
+  }
+
   def data: Seq[ResourceData[_ <: Data]] = Seq(i, o)
 }
 
diff --git a/src/main/scala/ee/hrzn/chryse/platform/resource/ResourceData.scala b/src/main/scala/ee/hrzn/chryse/platform/resource/ResourceData.scala
index e06f8e8..b9581d4 100644
--- a/src/main/scala/ee/hrzn/chryse/platform/resource/ResourceData.scala
+++ b/src/main/scala/ee/hrzn/chryse/platform/resource/ResourceData.scala
@@ -1,6 +1,7 @@
 package ee.hrzn.chryse.platform.resource
 
 import chisel3._
+import chisel3.experimental.Param
 import chisel3.experimental.dataview._
 import ee.hrzn.chryse.chisel.DirectionOf
 
@@ -18,6 +19,7 @@ abstract class ResourceData[HW <: Data](gen: => HW, invert: Boolean = false)
   final private[chryse] var pinId: Option[Pin] = None
   final var name: Option[String]               = None
   final protected var _invert                  = invert
+  final protected var _attribs                 = Map[String, Param]()
 
   // Should return Chisel datatype with Input/Output attached.
   def makeIo(): HW = gen
@@ -38,12 +40,14 @@ abstract class ResourceData[HW <: Data](gen: => HW, invert: Boolean = false)
     }
   }
 
-  final def makeIoConnection(): Unit = {
+  final def makeIoConnection(): HW = {
     if (topIoInst.isDefined)
       throw new IllegalStateException("topIoInst already defined")
-    val topIo = IO(makeIo()).suggestName(name.get)
+    // val topIo = IO(makeIo()).suggestName(name.get)
+    val topIo = Wire(makeIo()) // .suggestName(name.get)
     topIoInst = Some(topIo)
     connectIo(ioInst.get, topIo)
+    topIo
   }
 
   protected def connectIo(user: HW, top: HW): Unit = {
@@ -64,6 +68,11 @@ abstract class ResourceData[HW <: Data](gen: => HW, invert: Boolean = false)
     this
   }
 
+  def withAttributes(attribs: (String, Param)*): this.type = {
+    _attribs = attribs.to(Map)
+    this
+  }
+
   def data: Seq[ResourceData[_ <: Data]] = Seq(this)
 }
 
diff --git a/src/main/scala/ee/hrzn/chryse/platform/resource/ResourceSinglePin.scala b/src/main/scala/ee/hrzn/chryse/platform/resource/ResourceSinglePin.scala
index 31c84c3..77d0858 100644
--- a/src/main/scala/ee/hrzn/chryse/platform/resource/ResourceSinglePin.scala
+++ b/src/main/scala/ee/hrzn/chryse/platform/resource/ResourceSinglePin.scala
@@ -1,5 +1,8 @@
 package ee.hrzn.chryse.platform.resource
 
+import chisel3.experimental.Param
+
 trait ResourceSinglePin extends ResourceBase {
   def onPin(id: Pin): this.type
+  def withAttributes(attribs: (String, Param)*): this.type
 }
diff --git a/src/main/scala/ee/hrzn/chryse/platform/resource/SPIFlash.scala b/src/main/scala/ee/hrzn/chryse/platform/resource/SPIFlash.scala
index d4b3131..8e850c0 100644
--- a/src/main/scala/ee/hrzn/chryse/platform/resource/SPIFlash.scala
+++ b/src/main/scala/ee/hrzn/chryse/platform/resource/SPIFlash.scala
@@ -3,6 +3,8 @@ package ee.hrzn.chryse.platform.resource
 import chisel3._
 
 class SPIFlash extends ResourceBase {
+  // TODO: DSPI, QSPI
+
   val cs    = ResourceData(Output(Bool()), invert = true)
   val clock = ResourceData(Output(Clock()))
   val copi  = ResourceData(Output(Bool()))
diff --git a/src/main/scala/ee/hrzn/chryse/platform/resource/UART.scala b/src/main/scala/ee/hrzn/chryse/platform/resource/UART.scala
index 383bbf4..a888623 100644
--- a/src/main/scala/ee/hrzn/chryse/platform/resource/UART.scala
+++ b/src/main/scala/ee/hrzn/chryse/platform/resource/UART.scala
@@ -1,10 +1,9 @@
 package ee.hrzn.chryse.platform.resource
 
 import chisel3._
+import chisel3.experimental.Param
 
 class UART extends ResourceBase {
-  // TODO (iCE40): lower IO_STANDARD=SB_LVTTL and PULLUP=1.
-  // TODO: these will differ per-platform so need to come in from outside.
   val rx = ResourceData(Input(Bool()))
   val tx = ResourceData(Output(Bool()))
 
@@ -19,6 +18,12 @@ class UART extends ResourceBase {
     this
   }
 
+  def withAttributes(attribs: (String, Param)*): this.type = {
+    rx.withAttributes(attribs: _*)
+    tx.withAttributes(attribs: _*)
+    this
+  }
+
   def data: Seq[ResourceData[_ <: Data]] = Seq(rx, tx)
 }