diff --git a/conn.go b/conn.go
index d260dca6..564f072f 100644
--- a/conn.go
+++ b/conn.go
@@ -3,6 +3,7 @@ package ble
 import (
 	"context"
 	"io"
+	"time"
 )
 
 // Conn implements a L2CAP connection.
@@ -36,6 +37,15 @@ type Conn interface {
 	// ReadRSSI retrieves the current RSSI value of remote peripheral. [Vol 2, Part E, 7.5.4]
 	ReadRSSI() int
 
+	// ReadPHY retrieves the current PHY settings of the connection.
+	ReadPHY() (txPhy int, rxPhy int, err error)
+
+	// SetPHY sets the PHY for the connection.
+	SetPHY(txPhy int, rxPhy int) error
+
+	// UpdateConnection updates the connection parameters.
+	UpdateConnection(intervalMin time.Duration, intervalMax time.Duration, latency int, supervisionTimeout time.Duration) error
+
 	// Disconnected returns a receiving channel, which is closed when the connection disconnects.
 	Disconnected() <-chan struct{}
 }
diff --git a/darwin/conn.go b/darwin/conn.go
index 9aaba428..7f26447b 100644
--- a/darwin/conn.go
+++ b/darwin/conn.go
@@ -2,9 +2,11 @@ package darwin
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"log"
 	"sync"
+	"time"
 
 	"github.com/JuulLabs-OSS/cbgo"
 	"github.com/go-ble/ble"
@@ -159,6 +161,24 @@ func (c *conn) ReadRSSI() int {
 	}
 }
 
+// ReadPHY retrieves the current PHY settings of the connection.
+func (c *conn) ReadPHY() (int, int, error) {
+	// Not implemented for darwin
+	return 0, 0, errors.New("Not supported")
+}
+
+// SetPHY sets the PHY for the connection.
+func (c *conn) SetPHY(txPhy int, rxPhy int) error {
+	// Not implemented for darwin
+	return errors.New("Not supported")
+}
+
+// UpdateConnection updates the connection parameters.
+func (c *conn) UpdateConnection(intervalMin time.Duration, intervalMax time.Duration, latency int, supervisionTimeout time.Duration) error {
+	// Not implemented for darwin
+	return errors.New("Not supported")
+}
+
 // processChrRead handles an incoming read response.  CoreBluetooth does not
 // distinguish explicit reads from unsolicited notifications.  This function
 // identifies which type the incoming message is.
diff --git a/darwin/device.go b/darwin/device.go
index 05996e42..3d3882ef 100644
--- a/darwin/device.go
+++ b/darwin/device.go
@@ -408,3 +408,9 @@ func (d *Device) AdvertiseIBeacon(ctx context.Context, u ble.UUID, major, minor
 	b[20] = uint8(pwr)                        // Measured Tx Power
 	return d.AdvertiseIBeaconData(ctx, b)
 }
+
+// SetDefaultPHY sets the default PHYs for future connections.
+func (d *Device) SetDefaultPHY(txPhy int, rxPhy int) error {
+	// Not implemented for darwin
+	return errors.New("Not supported")
+}
diff --git a/device.go b/device.go
index ced686eb..1b3dfd22 100644
--- a/device.go
+++ b/device.go
@@ -42,4 +42,7 @@ type Device interface {
 
 	// Dial ...
 	Dial(ctx context.Context, a Addr) (Client, error)
+
+	// SetDefaultPHY sets the default PHYs for future connections.
+	SetDefaultPHY(txPhy int, rxPhy int) error
 }
diff --git a/linux/device.go b/linux/device.go
index 4876c50c..4e79efd8 100644
--- a/linux/device.go
+++ b/linux/device.go
@@ -220,3 +220,8 @@ func (d *Device) Dial(ctx context.Context, a ble.Addr) (ble.Client, error) {
 func (d *Device) Address() ble.Addr {
 	return d.HCI.Addr()
 }
+
+// SetDefaultPHY sets the default PHYs for future connections.
+func (d *Device) SetDefaultPHY(txPhy int, rxPhy int) error {
+	return d.HCI.SetDefaultPHY(txPhy, rxPhy)
+}
diff --git a/linux/hci/cmd/phy.go b/linux/hci/cmd/phy.go
new file mode 100644
index 00000000..142f1533
--- /dev/null
+++ b/linux/hci/cmd/phy.go
@@ -0,0 +1,79 @@
+package cmd
+
+// LEReadPHY implements LE Read PHY (0x08|0x0030) [Vol 2, Part E, 7.8.47]
+type LEReadPHY struct {
+	ConnectionHandle uint16
+}
+
+func (c *LEReadPHY) String() string {
+	return "LE Read PHY (0x08|0x0030)"
+}
+
+func (c *LEReadPHY) OpCode() int { return 0x08<<10 | 0x0030 }
+
+func (c *LEReadPHY) Len() int { return 2 }
+
+func (c *LEReadPHY) Marshal(b []byte) error {
+	return marshal(c, b)
+}
+
+// LEReadPHYRP returns the return parameter of LE Read PHY
+type LEReadPHYRP struct {
+	Status           uint8
+	ConnectionHandle uint16
+	TXPHY            uint8
+	RXPHY            uint8
+}
+
+func (c *LEReadPHYRP) Unmarshal(b []byte) error {
+	return unmarshal(c, b)
+}
+
+// LESetDefaultPHY implements LE Set Default PHY (0x08|0x0031) [Vol 2, Part E, 7.8.48]
+type LESetDefaultPHY struct {
+	ALLPHYS uint8
+	TXPHYS  uint8
+	RXPHYS  uint8
+}
+
+func (c *LESetDefaultPHY) String() string {
+	return "LE Set Default PHY (0x08|0x0031)"
+}
+
+func (c *LESetDefaultPHY) OpCode() int { return 0x08<<10 | 0x0031 }
+
+func (c *LESetDefaultPHY) Len() int { return 3 }
+
+func (c *LESetDefaultPHY) Marshal(b []byte) error {
+	return marshal(c, b)
+}
+
+// LESetDefaultPHYRP returns the return parameter of LE Set Default PHY
+type LESetDefaultPHYRP struct {
+	Status uint8
+}
+
+func (c *LESetDefaultPHYRP) Unmarshal(b []byte) error {
+	return unmarshal(c, b)
+}
+
+// LESetPHY implements LE Set PHY (0x08|0x0032) [Vol 2, Part E, 7.8.49]
+type LESetPHY struct {
+	ConnectionHandle uint16
+	ALLPHYS          uint8
+	TXPHYS           uint8
+	RXPHYS           uint8
+	PHYOptions       uint16
+}
+
+func (c *LESetPHY) String() string {
+	return "LE Set PHY (0x08|0x0032)"
+}
+
+func (c *LESetPHY) OpCode() int { return 0x08<<10 | 0x0032 }
+
+func (c *LESetPHY) Len() int { return 7 }
+
+func (c *LESetPHY) Marshal(b []byte) error {
+	return marshal(c, b)
+}
diff --git a/linux/hci/conn.go b/linux/hci/conn.go
index 24ff0c5f..3fafb9b3 100644
--- a/linux/hci/conn.go
+++ b/linux/hci/conn.go
@@ -7,6 +7,7 @@ import (
 	"fmt"
 	"io"
 	"net"
+	"time"
 
 	"github.com/go-ble/ble"
 	"github.com/go-ble/ble/linux/hci/cmd"
@@ -306,6 +307,61 @@ func (c *Conn) ReadRSSI() int {
 	return int(rp.RSSI)
 }
 
+// ReadPHY retrieves the current PHY settings of the connection. [Vol 2, Part E, 7.8.47]
+func (c *Conn) ReadPHY() (int, int, error) {
+	rp := new(cmd.LEReadPHYRP)
+	err := c.hci.Send(&cmd.LEReadPHY{
+		ConnectionHandle: c.param.ConnectionHandle(),
+	}, rp)
+	return int(rp.TXPHY), int(rp.RXPHY), err
+}
+
+// SetPHY sets the PHY for the connection. [Vol 2, Part E, 7.8.49]
+func (c *Conn) SetPHY(txPhy int, rxPhy int) error {
+	return c.hci.Send(&cmd.LESetPHY{
+		ConnectionHandle: c.param.ConnectionHandle(),
+		ALLPHYS:          0,
+		TXPHYS:           uint8(txPhy),
+		RXPHYS:           uint8(rxPhy),
+		PHYOptions:       0,
+	}, nil)
+}
+
+// UpdateConnection updates the connection parameters. [Vol 2, Part E, 7.8.18]
+func (c *Conn) UpdateConnection(intervalMin time.Duration, intervalMax time.Duration, latency int, supervisionTimeout time.Duration) error {
+	min := uint16(intervalMin / (1250 * time.Microsecond))
+	max := uint16(intervalMax / (1250 * time.Microsecond))
+	timeout := uint16(supervisionTimeout / (10 * time.Millisecond))
+
+	if c.param.Role() != roleMaster {
+		// As a slave, we should use the L2CAP Connection Parameter Update Request
+		req := &ConnectionParameterUpdateRequest{
+			IntervalMin:       min,
+			IntervalMax:       max,
+			SlaveLatency:      uint16(latency),
+			TimeoutMultiplier: timeout,
+		}
+		rsp := &ConnectionParameterUpdateResponse{}
+		if err := c.Signal(req, rsp); err != nil {
+			return err
+		}
+		if rsp.Result != 0 {
+			return fmt.Errorf("connection parameter update rejected: 0x%04x", rsp.Result)
+		}
+		return nil
+	}
+
+	return c.hci.Send(&cmd.LEConnectionUpdate{
+		ConnectionHandle:   c.param.ConnectionHandle(),
+		ConnIntervalMin:    min,
+		ConnIntervalMax:    max,
+		ConnLatency:        uint16(latency),
+		SupervisionTimeout: timeout,
+		MinimumCELength:    0x0000,
+		MaximumCELength:    0x0000,
+	}, nil)
+}
+
 // Close disconnects the connection by sending hci disconnect command to the device.
 func (c *Conn) Close() error {
 	select {
diff --git a/linux/hci/evt/phy.go b/linux/hci/evt/phy.go
new file mode 100644
index 00000000..7a1520f8
--- /dev/null
+++ b/linux/hci/evt/phy.go
@@ -0,0 +1,20 @@
+package evt
+
+import "encoding/binary"
+
+const LEPHYUpdateCompleteSubCode = 0x0C
+
+// LEPHYUpdateComplete implements LE PHY Update Complete (0x3E:0x0C) [Vol 2, Part E, 7.7.65.12].
+type LEPHYUpdateComplete []byte
+
+func (r LEPHYUpdateComplete) SubeventCode() uint8 { return r[0] }
+
+func (r LEPHYUpdateComplete) Status() uint8 { return r[1] }
+
+func (r LEPHYUpdateComplete) ConnectionHandle() uint16 {
+	return binary.LittleEndian.Uint16(r[2:])
+}
+
+func (r LEPHYUpdateComplete) TXPHY() uint8 { return r[4] }
+
+func (r LEPHYUpdateComplete) RXPHY() uint8 { return r[5] }
diff --git a/linux/hci/hci.go b/linux/hci/hci.go
index bd9b3a80..c93295e9 100644
--- a/linux/hci/hci.go
+++ b/linux/hci/hci.go
@@ -133,6 +133,7 @@ func (h *HCI) Init() error {
 	h.subh[evt.LEConnectionCompleteSubCode] = h.handleLEConnectionComplete
 	h.subh[evt.LEConnectionUpdateCompleteSubCode] = h.handleLEConnectionUpdateComplete
 	h.subh[evt.LELongTermKeyRequestSubCode] = h.handleLELongTermKeyRequest
+	h.subh[evt.LEPHYUpdateCompleteSubCode] = h.handleLEPHYUpdateComplete
 	// evt.EncryptionChangeCode:                     todo),
 	// evt.ReadRemoteVersionInformationCompleteCode: todo),
 	// evt.HardwareErrorCode:                        todo),
@@ -230,6 +231,23 @@ func (h *HCI) init() error {
 	return h.err
 }
 
+// SetDefaultPHY sets the default PHYs for future connections. [Vol 2, Part E, 7.8.48]
+func (h *HCI) SetDefaultPHY(txPhy int, rxPhy int) error {
+	rp := new(cmd.LESetDefaultPHYRP)
+	err := h.Send(&cmd.LESetDefaultPHY{
+		ALLPHYS: 0,
+		TXPHYS:  uint8(txPhy),
+		RXPHYS:  uint8(rxPhy),
+	}, rp)
+	if err != nil {
+		return err
+	}
+	if rp.Status != 0 {
+		return fmt.Errorf("failed to set default PHY: status 0x%02x", rp.Status)
+	}
+	return nil
+}
+
 // Send ...
 func (h *HCI) Send(c Command, r CommandRP) error {
 	// Only allow one send after another to prevent race condition
@@ -527,6 +545,10 @@ func (h *HCI) handleLEConnectionUpdateComplete(b []byte) error {
 	return nil
 }
 
+func (h *HCI) handleLEPHYUpdateComplete(b []byte) error {
+	return nil
+}
+
 func (h *HCI) handleDisconnectionComplete(b []byte) error {
 	e := evt.DisconnectionComplete(b)
 	h.muConns.Lock()
diff --git a/linux/hci/signal.go b/linux/hci/signal.go
index 9a18745c..1ecbb211 100644
--- a/linux/hci/signal.go
+++ b/linux/hci/signal.go
@@ -64,7 +64,8 @@ func (c *Conn) Signal(req Signal, rsp Signal) error {
 		return errors.New("signaling request timed out")
 	}
 
-	if s.code() != req.Code() {
+	// The connection parameter update request will trigger an update response.
+	if s.code() != req.Code() && !(req.Code() == SignalConnectionParameterUpdateRequest && s.code() == SignalConnectionParameterUpdateResponse) {
 		return errors.New("mismatched signaling response")
 	}
 	if s.id() != c.sigID {