diff --git a/ecp5/arch.cc b/ecp5/arch.cc
index d887aa69..371dbb12 100644
--- a/ecp5/arch.cc
+++ b/ecp5/arch.cc
@@ -329,6 +329,44 @@ std::string Arch::getBelPackagePin(BelId bel) const
     return "";
 }
 
+int Arch::getPioBelBank(BelId bel) const
+{
+    for (int i = 0; i < chip_info->num_pios; i++) {
+        if (chip_info->pio_info[i].abs_loc == bel.location && chip_info->pio_info[i].bel_index == bel.index) {
+            return chip_info->pio_info[i].bank;
+        }
+    }
+    NPNR_ASSERT_FALSE("failed to find PIO");
+}
+
+std::string Arch::getPioFunctionName(BelId bel) const
+{
+    for (int i = 0; i < chip_info->num_pios; i++) {
+        if (chip_info->pio_info[i].abs_loc == bel.location && chip_info->pio_info[i].bel_index == bel.index) {
+            const char *func = chip_info->pio_info[i].function_name.get();
+            if (func == nullptr)
+                return "";
+            else
+                return func;
+        }
+    }
+    NPNR_ASSERT_FALSE("failed to find PIO");
+}
+
+BelId Arch::getPioByFunctionName(const std::string &name) const
+{
+    for (int i = 0; i < chip_info->num_pios; i++) {
+        const char *func = chip_info->pio_info[i].function_name.get();
+        if (func != nullptr && func == name) {
+            BelId bel;
+            bel.location = chip_info->pio_info[i].abs_loc;
+            bel.index = chip_info->pio_info[i].bel_index;
+            return bel;
+        }
+    }
+    return BelId();
+}
+
 std::vector<PortPin> Arch::getBelPins(BelId bel) const
 
 {
diff --git a/ecp5/arch.h b/ecp5/arch.h
index 38362d6b..c2efb2bd 100644
--- a/ecp5/arch.h
+++ b/ecp5/arch.h
@@ -733,6 +733,10 @@ struct Arch : BaseCtx
 
     BelId getPackagePinBel(const std::string &pin) const;
     std::string getBelPackagePin(BelId bel) const;
+    int getPioBelBank(BelId bel) const;
+    // For getting GCLK, PLL, Vref, etc, pins
+    std::string getPioFunctionName(BelId bel) const;
+    BelId getPioByFunctionName(const std::string &name) const;
 
     PortType getBelPinType(BelId bel, PortPin pin) const;
 
diff --git a/ecp5/io.cc b/ecp5/io.cc
new file mode 100644
index 00000000..e86c84f6
--- /dev/null
+++ b/ecp5/io.cc
@@ -0,0 +1,217 @@
+/*
+ *  nextpnr -- Next Generation Place and Route
+ *
+ *  Copyright (C) 2018  David Shah <david@symbioticeda.com>
+ *
+ *  Permission to use, copy, modify, and/or distribute this software for any
+ *  purpose with or without fee is hereby granted, provided that the above
+ *  copyright notice and this permission notice appear in all copies.
+ *
+ *  THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ *  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ *  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ *  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ *  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ *  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ *  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ *
+ */
+
+#include "io.h"
+
+NEXTPNR_NAMESPACE_BEGIN
+
+std::string iovoltage_to_str(IOVoltage v)
+{
+    switch (v) {
+    case IOVoltage::VCC_3V3:
+        return "3V3";
+    case IOVoltage::VCC_2V5:
+        return "2V5";
+    case IOVoltage::VCC_1V8:
+        return "1V8";
+    case IOVoltage::VCC_1V5:
+        return "1V5";
+    case IOVoltage::VCC_1V35:
+        return "1V35";
+    case IOVoltage::VCC_1V2:
+        return "1V2";
+    }
+    NPNR_ASSERT_FALSE("unknown IO voltage");
+}
+
+IOVoltage iovoltage_from_str(const std::string &name)
+{
+    if (name == "3V3")
+        return IOVoltage::VCC_3V3;
+    if (name == "2V5")
+        return IOVoltage::VCC_2V5;
+    if (name == "1V8")
+        return IOVoltage::VCC_1V8;
+    if (name == "1V5")
+        return IOVoltage::VCC_1V5;
+    if (name == "1V35")
+        return IOVoltage::VCC_1V35;
+    if (name == "1V2")
+        return IOVoltage::VCC_1V2;
+    NPNR_ASSERT_FALSE("unknown IO voltage");
+}
+
+std::string iotype_to_str(IOType type)
+{
+    if (type == IOType::TYPE_NONE)
+        return "NONE";
+#define X(t)                                                                                                           \
+    if (type == IOType::t)                                                                                             \
+        return #t;
+#include "iotypes.inc"
+#undef X
+    if (type == IOType::TYPE_UNKNOWN)
+        return "<unknown>";
+    NPNR_ASSERT_FALSE("unknown IO type");
+}
+
+IOType ioType_from_str(const std::string &name)
+{
+    if (name == "NONE")
+        return IOType::TYPE_NONE;
+#define X(t)                                                                                                           \
+    if (name == #t)                                                                                                    \
+        return IOType::t;
+#include "iotypes.inc"
+    return IOType::TYPE_UNKNOWN;
+}
+
+IOVoltage get_vccio(IOType type)
+{
+    switch (type) {
+    case IOType::LVTTL33:
+    case IOType::LVCMOS33:
+    case IOType::LVCMOS33D:
+    case IOType::LVPECL33:
+    case IOType::LVPECL33E:
+        return IOVoltage::VCC_3V3;
+    case IOType::LVCMOS25:
+    case IOType::LVCMOS25D:
+    case IOType::LVDS:
+    case IOType::SLVS:
+    case IOType::SUBLVDS:
+    case IOType::LVDS25E:
+    case IOType::MLVDS25:
+    case IOType::MLVDS25E:
+    case IOType::BLVDS25:
+        return IOVoltage::VCC_2V5;
+    case IOType::LVCMOS18:
+    case IOType::LVCMOS18D:
+    case IOType::SSTL18_I:
+    case IOType::SSTL18_II:
+    case IOType::SSTL18D_I:
+    case IOType::SSTL18D_II:
+        return IOVoltage::VCC_1V8;
+    case IOType::LVCMOS15:
+    case IOType::SSTL15_I:
+    case IOType::SSTL15_II:
+    case IOType::SSTL15D_I:
+    case IOType::SSTL15D_II:
+        return IOVoltage::VCC_1V5;
+    case IOType::SSTL135_I:
+    case IOType::SSTL135_II:
+    case IOType::SSTL135D_I:
+    case IOType::SSTL135D_II:
+        return IOVoltage::VCC_1V35;
+    case IOType::LVCMOS12:
+    case IOType::HSUL12:
+    case IOType::HSUL12D:
+        return IOVoltage::VCC_1V2;
+    default:
+        NPNR_ASSERT_FALSE("unknown IO type, unable to determine VccIO");
+    }
+}
+
+bool is_strong_vccio_constraint(IOType type, PortType dir, IOSide side)
+{
+    if (dir == PORT_OUT || dir == PORT_INOUT)
+        return true;
+    switch (type) {
+    case IOType::TYPE_NONE:
+    case IOType::LVCMOS33D:
+    case IOType::LVPECL33:
+    case IOType::LVDS:
+    case IOType::MLVDS25:
+    case IOType::BLVDS25:
+    case IOType::SLVS:
+    case IOType::SUBLVDS:
+    case IOType::LVCMOS12:
+    case IOType::HSUL12:
+    case IOType::HSUL12D:
+        return false;
+    case IOType::LVCMOS33:
+    case IOType::LVTTL33:
+    case IOType::LVCMOS25:
+        return (side == IOSide::LEFT || side == IOSide::RIGHT);
+    default:
+        return true;
+    }
+}
+
+bool is_differential(IOType type)
+{
+    switch (type) {
+    case IOType::LVCMOS33D:
+    case IOType::LVCMOS25D:
+    case IOType::LVPECL33:
+    case IOType::LVDS:
+    case IOType::MLVDS25:
+    case IOType::BLVDS25:
+    case IOType::SLVS:
+    case IOType::SUBLVDS:
+    case IOType::LVCMOS18D:
+    case IOType::SSTL18D_I:
+    case IOType::SSTL18D_II:
+    case IOType::SSTL15D_I:
+    case IOType::SSTL15D_II:
+    case IOType::SSTL135D_I:
+    case IOType::SSTL135D_II:
+    case IOType::HSUL12D:
+        return true;
+    default:
+        return false;
+    }
+}
+
+bool is_referenced(IOType type)
+{
+    switch (type) {
+    case IOType::SSTL18_I:
+    case IOType::SSTL18_II:
+    case IOType::SSTL18D_I:
+    case IOType::SSTL18D_II:
+    case IOType::SSTL15_I:
+    case IOType::SSTL15_II:
+    case IOType::SSTL15D_I:
+    case IOType::SSTL15D_II:
+    case IOType::SSTL135_I:
+    case IOType::SSTL135_II:
+    case IOType::SSTL135D_I:
+    case IOType::SSTL135D_II:
+    case IOType::HSUL12:
+    case IOType::HSUL12D:
+        return true;
+    default:
+        return false;
+    }
+}
+
+bool valid_loc_for_io(IOType type, PortType dir, IOSide side, int z)
+{
+    bool is_lr = side == IOSide::LEFT || side == IOSide::RIGHT;
+    if (is_referenced(type) && !is_lr)
+        return false;
+    if (is_differential(type) && (!is_lr || ((z % 2) == 1)))
+        return false;
+    if ((type == IOType::LVCMOS18D || type == IOType::LVDS) && (dir == PORT_OUT || PORT_INOUT) && z != 0)
+        return false;
+    return true;
+}
+
+NEXTPNR_NAMESPACE_END
diff --git a/ecp5/io.h b/ecp5/io.h
new file mode 100644
index 00000000..f0d941d9
--- /dev/null
+++ b/ecp5/io.h
@@ -0,0 +1,70 @@
+/*
+ *  nextpnr -- Next Generation Place and Route
+ *
+ *  Copyright (C) 2018  David Shah <david@symbioticeda.com>
+ *
+ *  Permission to use, copy, modify, and/or distribute this software for any
+ *  purpose with or without fee is hereby granted, provided that the above
+ *  copyright notice and this permission notice appear in all copies.
+ *
+ *  THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ *  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ *  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ *  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ *  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ *  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ *  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ *
+ */
+
+#ifndef IO_H
+#define IO_H
+
+#include "nextpnr.h"
+
+NEXTPNR_NAMESPACE_BEGIN
+
+enum class IOVoltage
+{
+    VCC_3V3,
+    VCC_2V5,
+    VCC_1V8,
+    VCC_1V5,
+    VCC_1V35,
+    VCC_1V2
+};
+
+std::string iovoltage_to_str(IOVoltage v);
+IOVoltage iovoltage_from_str(const std::string &name);
+
+enum class IOType
+{
+    TYPE_NONE,
+#define X(t) t,
+#include "iotypes.inc"
+#undef X
+    TYPE_UNKNOWN,
+};
+
+enum class IOSide
+{
+    LEFT,
+    RIGHT,
+    TOP,
+    BOTTOM,
+};
+
+std::string iotype_to_str(IOType type);
+IOType ioType_from_str(const std::string &name);
+
+// IO related functions
+IOVoltage get_vccio(IOType type);
+bool is_strong_vccio_constraint(IOType type, PortType dir, IOSide side);
+bool is_differential(IOType type);
+bool is_referenced(IOType type);
+
+bool valid_loc_for_io(IOType type, PortType dir, IOSide side, int z);
+
+NEXTPNR_NAMESPACE_END
+
+#endif
diff --git a/ecp5/iotypes.inc b/ecp5/iotypes.inc
new file mode 100644
index 00000000..5984e79e
--- /dev/null
+++ b/ecp5/iotypes.inc
@@ -0,0 +1,37 @@
+X(LVTTL33)
+X(LVCMOS33)
+X(LVCMOS25)
+X(LVCMOS18)
+X(LVCMOS15)
+X(LVCMOS12)
+
+X(SSTL18_I)
+X(SSTL18_II)
+X(SSTL15_I)
+X(SSTL15_II)
+X(SSTL135_I)
+X(SSTL135_II)
+X(HSUL12)
+
+X(SSTL18D_I)
+X(SSTL18D_II)
+X(SSTL135D_I)
+X(SSTL135D_II)
+X(SSTL15D_I)
+X(SSTL15D_II)
+X(HSUL12D)
+X(LVCMOS33D)
+X(LVCMOS25D)
+
+X(LVDS)
+X(BLVDS25)
+X(MLVDS25)
+X(LVPECL33)
+X(SLVS)
+X(SUBLVDS)
+X(LVCMOS18D)
+
+X(LVDS25E)
+X(BLVDS25E)
+X(MLVDS25E)
+X(LVPECL33E)
diff --git a/gui/designwidget.cc b/gui/designwidget.cc
index 91ec5163..e63ee937 100644
--- a/gui/designwidget.cc
+++ b/gui/designwidget.cc
@@ -229,6 +229,7 @@ void DesignWidget::addToHistory(QTreeWidgetItem *item)
 
 void DesignWidget::newContext(Context *ctx)
 {
+    highlightSelected.clear();
     treeWidget->clear();
     // reset pointers since they are not valid after clear
     nets_root = nullptr;
@@ -337,48 +338,78 @@ void DesignWidget::newContext(Context *ctx)
     for (auto pip : nameToItem[2].toStdMap()) {
         pip_root->addChild(pip.second);
     }
+
+    nets_root = new QTreeWidgetItem(treeWidget);
+    nets_root->setText(0, "Nets");
+    treeWidget->insertTopLevelItem(0, nets_root);
+
+    cells_root = new QTreeWidgetItem(treeWidget);
+    cells_root->setText(0, "Cells");
+    treeWidget->insertTopLevelItem(0, cells_root);
+
     updateTree();
 }
 
 void DesignWidget::updateTree()
 {
-    clearProperties();
-    delete nets_root;
-    delete cells_root;
-    nameToItem[3].clear();
-    nameToItem[4].clear();
+    if (!ctx)
+        return;
 
+    clearProperties();
+
+    // treeWidget->setSortingEnabled(false);
+
+    // Remove nets not existing any more
+    QMap<QString, QTreeWidgetItem *>::iterator i = nameToItem[3].begin();
+    while (i != nameToItem[3].end()) {
+        QMap<QString, QTreeWidgetItem *>::iterator prev = i;
+        ++i;
+        if (ctx->nets.find(ctx->id(prev.key().toStdString())) == ctx->nets.end()) {
+            if (treeWidget->currentItem() == prev.value())
+                treeWidget->setCurrentItem(nets_root);
+            if (highlightSelected.contains(prev.value()))
+                highlightSelected.remove(prev.value());
+            delete prev.value();
+            nameToItem[3].erase(prev);
+        }
+    }
     // Add nets to tree
-    nets_root = new QTreeWidgetItem(treeWidget);
-    nets_root->setText(0, "Nets");
-    treeWidget->insertTopLevelItem(0, nets_root);
-    if (ctx) {
-        for (auto &item : ctx->nets) {
-            auto id = item.first;
-            QString name = QString(id.c_str(ctx));
+    for (auto &item : ctx->nets) {
+        auto id = item.first;
+        QString name = QString(id.c_str(ctx));
+        if (!nameToItem[3].contains(name)) {
             IdStringTreeItem *newItem = new IdStringTreeItem(id, ElementType::NET, name, nullptr);
+            nets_root->addChild(newItem);
             nameToItem[3].insert(name, newItem);
         }
     }
-    for (auto item : nameToItem[3].toStdMap()) {
-        nets_root->addChild(item.second);
-    }
 
+    // Remove cells not existing any more
+    i = nameToItem[4].begin();
+    while (i != nameToItem[4].end()) {
+        QMap<QString, QTreeWidgetItem *>::iterator prev = i;
+        ++i;
+        if (ctx->cells.find(ctx->id(prev.key().toStdString())) == ctx->cells.end()) {
+            if (treeWidget->currentItem() == prev.value())
+                treeWidget->setCurrentItem(cells_root);
+            if (highlightSelected.contains(prev.value()))
+                highlightSelected.remove(prev.value());
+            delete prev.value();
+            nameToItem[4].erase(prev);
+        }
+    }
     // Add cells to tree
-    cells_root = new QTreeWidgetItem(treeWidget);
-    cells_root->setText(0, "Cells");
-    treeWidget->insertTopLevelItem(0, cells_root);
-    if (ctx) {
-        for (auto &item : ctx->cells) {
-            auto id = item.first;
-            QString name = QString(id.c_str(ctx));
+    for (auto &item : ctx->cells) {
+        auto id = item.first;
+        QString name = QString(id.c_str(ctx));
+        if (!nameToItem[4].contains(name)) {
             IdStringTreeItem *newItem = new IdStringTreeItem(id, ElementType::CELL, name, nullptr);
+            cells_root->addChild(newItem);
             nameToItem[4].insert(name, newItem);
         }
     }
-    for (auto item : nameToItem[4].toStdMap()) {
-        cells_root->addChild(item.second);
-    }
+    // treeWidget->sortByColumn(0, Qt::AscendingOrder);
+    // treeWidget->setSortingEnabled(true);
 }
 QtProperty *DesignWidget::addTopLevelProperty(const QString &id)
 {
diff --git a/gui/fpgaviewwidget.cc b/gui/fpgaviewwidget.cc
index 9343419b..e21af678 100644
--- a/gui/fpgaviewwidget.cc
+++ b/gui/fpgaviewwidget.cc
@@ -289,6 +289,9 @@ FPGAViewWidget::~FPGAViewWidget() {}
 void FPGAViewWidget::newContext(Context *ctx)
 {
     ctx_ = ctx;
+    onSelectedArchItem(std::vector<DecalXY>());
+    for (int i = 0; i < 8; i++)
+        onHighlightGroupChanged(std::vector<DecalXY>(), i);
     pokeRenderer();
 }
 
diff --git a/gui/ice40/worker.cc b/gui/ice40/worker.cc
index 09093ec8..fd46ecad 100644
--- a/gui/ice40/worker.cc
+++ b/gui/ice40/worker.cc
@@ -109,7 +109,6 @@ void Worker::budget(double freq)
     Q_EMIT taskStarted();
     try {
         ctx->target_freq = freq;
-        assign_budget(ctx);
         Q_EMIT budget_finish(true);
     } catch (WorkerInterruptionRequested) {
         Q_EMIT taskCanceled();
@@ -121,6 +120,8 @@ void Worker::place(bool timing_driven)
     Q_EMIT taskStarted();
     try {
         ctx->timing_driven = timing_driven;
+        log_info("Assigned budget %0.2f MHz", ctx->target_freq / 1e6);
+        assign_budget(ctx);
         Q_EMIT place_finished(ctx->place());
     } catch (WorkerInterruptionRequested) {
         Q_EMIT taskCanceled();