diff --git a/devices/ds18b20/ds18b20_test.go b/devices/ds18b20/ds18b20_test.go
index 9f87312..a434d95 100644
--- a/devices/ds18b20/ds18b20_test.go
+++ b/devices/ds18b20/ds18b20_test.go
@@ -5,20 +5,28 @@
 package ds18b20
 
 import (
-	"os"
 	"testing"
 	"time"
 
 	"periph.io/x/periph/conn/onewire"
 	"periph.io/x/periph/conn/onewire/onewiretest"
 	"periph.io/x/periph/devices"
-	"periph.io/x/periph/host"
 )
 
-// TestMain lets periph load all drivers and then runs the tests.
-func TestMain(m *testing.M) {
-	host.Init()
-	os.Exit(m.Run())
+func TestNew_resolution(t *testing.T) {
+	bus := &onewiretest.Playback{}
+	var addr onewire.Address = 0x740000070e41ac28
+	if d, err := New(bus, addr, 1); d != nil || err == nil {
+		t.Fatal("invalid resolution")
+	}
+}
+
+func TestNew_read(t *testing.T) {
+	bus := &onewiretest.Playback{DontPanic: true}
+	var addr onewire.Address = 0x740000070e41ac28
+	if d, err := New(bus, addr, 9); d != nil || err == nil {
+		t.Fatal("invalid resolution")
+	}
 }
 
 // TestTemperature tests a temperature conversion on a ds18b20 using
@@ -27,20 +35,26 @@ func TestTemperature(t *testing.T) {
 	// set-up playback using the recording output.
 	ops := []onewiretest.IO{
 		// Match ROM + Read Scratchpad (init)
-		{Write: []uint8{0x55, 0x28, 0xac, 0x41, 0xe, 0x7, 0x0, 0x0, 0x74, 0xbe},
-			Read: []uint8{0xe0, 0x1, 0x0, 0x0, 0x3f, 0xff, 0x10, 0x10, 0x3f}, Pull: false},
+		{
+			Write: []uint8{0x55, 0x28, 0xac, 0x41, 0xe, 0x7, 0x0, 0x0, 0x74, 0xbe},
+			Read:  []uint8{0xe0, 0x1, 0x0, 0x0, 0x3f, 0xff, 0x10, 0x10, 0x3f},
+		},
 		// Match ROM + Convert
-		{Write: []uint8{0x55, 0x28, 0xac, 0x41, 0xe, 0x7, 0x0, 0x0, 0x74, 0x44},
-			Read: []uint8(nil), Pull: true},
+		{
+			Write: []uint8{0x55, 0x28, 0xac, 0x41, 0xe, 0x7, 0x0, 0x0, 0x74, 0x44},
+			Pull:  true,
+		},
 		// Match ROM + Read Scratchpad (read temp)
-		{Write: []uint8{0x55, 0x28, 0xac, 0x41, 0xe, 0x7, 0x0, 0x0, 0x74, 0xbe},
-			Read: []uint8{0xe0, 0x1, 0x0, 0x0, 0x3f, 0xff, 0x10, 0x10, 0x3f}, Pull: false},
+		{
+			Write: []uint8{0x55, 0x28, 0xac, 0x41, 0xe, 0x7, 0x0, 0x0, 0x74, 0xbe},
+			Read:  []uint8{0xe0, 0x1, 0x0, 0x0, 0x3f, 0xff, 0x10, 0x10, 0x3f},
+		},
 	}
 	var addr onewire.Address = 0x740000070e41ac28
 	var temp devices.Celsius = 30000 // 30.000°C
-	owBus := &onewiretest.Playback{Ops: ops}
+	bus := onewiretest.Playback{Ops: ops}
 	// Init the ds18b20.
-	ds18b20, err := New(owBus, addr, 10)
+	ds18b20, err := New(&bus, addr, 10)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -59,6 +73,9 @@ func TestTemperature(t *testing.T) {
 	if dt < 188*time.Millisecond {
 		t.Errorf("expected conversion to take >187ms, took %s", dt)
 	}
+	if err := bus.Close(); err != nil {
+		t.Fatal(err)
+	}
 }
 
 // TestConvertAll tests a temperature conversion on all ds18b20 using
@@ -69,16 +86,33 @@ func TestConvertAll(t *testing.T) {
 		// Skip ROM + Convert
 		{Write: []uint8{0xcc, 0x44}, Read: []uint8(nil), Pull: true},
 	}
-	owBus := &onewiretest.Playback{Ops: ops}
+	bus := onewiretest.Playback{Ops: ops}
 	// Perform the conversion
 	t0 := time.Now()
-	if err := ConvertAll(owBus, 9); err != nil {
+	if err := ConvertAll(&bus, 9); err != nil {
 		t.Fatal(err)
 	}
 	// Expect it to take >93ms
 	if dt := time.Since(t0); dt < 94*time.Millisecond {
 		t.Errorf("expected conversion to take >93ms, took %s", dt)
 	}
+	if err := bus.Close(); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestConvertAll_resolution(t *testing.T) {
+	bus := &onewiretest.Playback{}
+	if err := ConvertAll(bus, 1); err == nil {
+		t.Fatal("invalid resolution")
+	}
+}
+
+func TestConvertAll_fail(t *testing.T) {
+	bus := &onewiretest.Playback{DontPanic: true}
+	if err := ConvertAll(bus, 9); err == nil {
+		t.Fatal("invalid resolution")
+	}
 }
 
 /* Commented out in order not to import periph/host, need to move to smoke test
diff --git a/devices/ds248x/dev.go b/devices/ds248x/dev.go
index 7ccb246..926371d 100644
--- a/devices/ds248x/dev.go
+++ b/devices/ds248x/dev.go
@@ -13,15 +13,18 @@ import (
 	"periph.io/x/periph/conn/onewire"
 )
 
-// Dev is a handle to a ds248x device and it implements the onewire.Bus interface.
+// Dev is a handle to a ds248x device and it implements the onewire.Bus
+// interface.
 //
-// Dev implements a persistent error model: if a fatal error is encountered it places
-// itself into an error state and immediately returns the last error on all subsequent
-// calls. A fresh Dev, which reinitializes the hardware, must be created to proceed.
+// Dev implements a persistent error model: if a fatal error is encountered it
+// places itself into an error state and immediately returns the last error on
+// all subsequent calls. A fresh Dev, which reinitializes the hardware, must be
+// created to proceed.
 //
-// A persistent error is only set when there is a problem with the ds248x device itself
-// (or the I²C bus used to access it). Errors on the 1-wire bus do not cause persistent
-// errors and implement the onewire.BusError interface to indicate this fact.
+// A persistent error is only set when there is a problem with the ds248x
+// device itself (or the I²C bus used to access it). Errors on the 1-wire bus
+// do not cause persistent errors and implement the onewire.BusError interface
+// to indicate this fact.
 type Dev struct {
 	sync.Mutex               // lock for the bus while a transaction is in progress
 	i2c        conn.Conn     // i2c device handle for the ds248x
@@ -32,24 +35,16 @@ type Dev struct {
 	err        error         // persistent error, device will no longer operate
 }
 
-// String
 func (d *Dev) String() string {
-	return fmt.Sprintf("ds248x")
+	return "ds248x"
 }
 
-// Close drops the I²C bus handle and sets a persistent error.
-func (d *Dev) Close() error {
-	d.i2c = nil
-	d.err = fmt.Errorf("ds248x: invalid operation on closed bus")
-	return nil
-}
-
-// Tx performs a bus transaction, sending and receiving bytes, and
-// ending by pulling the bus high either weakly or strongly depending
-// on the value of power.
+// Tx performs a bus transaction, sending and receiving bytes, and ending by
+// pulling the bus high either weakly or strongly depending on the value of
+// power.
 //
-// A strong pull-up is typically required to power temperature conversion
-// or EEPROM writes.
+// A strong pull-up is typically required to power temperature conversion or
+// EEPROM writes.
 func (d *Dev) Tx(w, r []byte, power onewire.Pullup) error {
 	d.Lock()
 	defer d.Unlock()
@@ -85,9 +80,9 @@ func (d *Dev) Tx(w, r []byte, power onewire.Pullup) error {
 	return d.err
 }
 
-// Search performs a "search" cycle on the 1-wire bus and returns the
-// addresses of all devices on the bus if alarmOnly is false and of all
-// devices in alarm state if alarmOnly is true.
+// Search performs a "search" cycle on the 1-wire bus and returns the addresses
+// of all devices on the bus if alarmOnly is false and of all devices in alarm
+// state if alarmOnly is true.
 //
 // If an error occurs during the search the already-discovered devices are
 // returned with the error.
@@ -95,8 +90,8 @@ func (d *Dev) Search(alarmOnly bool) ([]onewire.Address, error) {
 	return onewire.Search(d, alarmOnly)
 }
 
-// SearchTriplet performs a single bit search triplet command on the bus,
-// waits for it to complete and returs the outcome.
+// SearchTriplet performs a single bit search triplet command on the bus, waits
+// for it to complete and returs the outcome.
 //
 // SearchTriplet should not be used directly, use Search instead.
 func (d *Dev) SearchTriplet(direction byte) (onewire.TripletResult, error) {
@@ -136,7 +131,8 @@ func (d *Dev) reset() (bool, error) {
 	return (status & 2) != 0, nil
 }
 
-// i2cTx is a helper function to call i2c.Tx and handle the error by persisting it.
+// i2cTx is a helper function to call i2c.Tx and handle the error by persisting
+// it.
 func (d *Dev) i2cTx(w, r []byte) {
 	if d.err != nil {
 		return
@@ -147,11 +143,11 @@ func (d *Dev) i2cTx(w, r []byte) {
 // waitIdle waits for the one wire bus to be idle.
 //
 // It initially sleeps for the delay and then polls the status register and
-// sleeps for a tenth of the delay each time the status register indicates
-// that the bus is still busy. The last read status byte is returned.
+// sleeps for a tenth of the delay each time the status register indicates that
+// the bus is still busy. The last read status byte is returned.
 //
-// An overall timeout of 3ms is applied to the whole procedure. waitIdle
-// uses the persistent error model and returns 0 if there is an error.
+// An overall timeout of 3ms is applied to the whole procedure. waitIdle uses
+// the persistent error model and returns 0 if there is an error.
 func (d *Dev) waitIdle(delay time.Duration) byte {
 	if d.err != nil {
 		return 0
diff --git a/devices/ds248x/ds248x_test.go b/devices/ds248x/ds248x_test.go
index cd446b7..a5a34b3 100644
--- a/devices/ds248x/ds248x_test.go
+++ b/devices/ds248x/ds248x_test.go
@@ -6,56 +6,79 @@ package ds248x
 
 import (
 	"fmt"
+	"log"
 	"testing"
 
 	"periph.io/x/periph/conn/i2c/i2creg"
 	"periph.io/x/periph/conn/i2c/i2ctest"
 )
 
-// TestInit tests the initialization of a ds2483 using a recording.
-func TestInit(t *testing.T) {
-	var ops = []i2ctest.IO{
-		{Addr: 0x18, Write: []byte{0xf0}, Read: []byte(nil)},
-		{Addr: 0x18, Write: []byte{0xe1, 0xf0}, Read: []byte{0x18}},
-		{Addr: 0x18, Write: []byte{0xd2, 0xe1}, Read: []byte{0x1}},
-		{Addr: 0x18, Write: []byte{0xe1, 0xb4}, Read: []byte(nil)},
-		{Addr: 0x18, Write: []byte{0xc3, 0x6, 0x26, 0x46, 0x66, 0x86}, Read: []byte(nil)},
-		{Addr: 0x18, Write: []byte{0x78, 0x0}, Read: []byte(nil)},
-		{Addr: 0x18, Write: []byte{}, Read: []byte{0xe8}},
-	}
-
-	bus := &i2ctest.Playback{Ops: ops}
-	if _, err := New(bus, nil); err != nil {
-		t.Fatal(err)
-	}
-}
-
 func Example() {
 	// Open the I²C bus to which the DS248x is connected.
 	i2cBus, err := i2creg.Open("")
 	if err != nil {
-		fmt.Println(err)
-		return
+		log.Fatal(err)
 	}
 	defer i2cBus.Close()
 
 	// Open the DS248x to get a 1-wire bus.
 	owBus, err := New(i2cBus, nil)
 	if err != nil {
-		fmt.Println(err)
-		return
+		log.Fatal(err)
 	}
 	// Search devices on the bus
 	devices, err := owBus.Search(false)
 	if err != nil {
-		fmt.Println(err)
-		return
+		log.Fatal(err)
 	}
 	fmt.Printf("Found %d 1-wire devices: ", len(devices))
 	for _, d := range devices {
 		fmt.Printf(" %#16x", uint64(d))
 	}
-	fmt.Print('\n')
+	fmt.Print("\n")
+}
+
+//
+
+func TestNew(t *testing.T) {
+	bus := i2ctest.Playback{
+		Ops: []i2ctest.IO{
+			{Addr: 0x18, Write: []byte{0xf0}},
+			{Addr: 0x18, Write: []byte{0xe1, 0xf0}, Read: []byte{0x18}},
+			{Addr: 0x18, Write: []byte{0xd2, 0xe1}, Read: []byte{0x1}},
+			{Addr: 0x18, Write: []byte{0xe1, 0xb4}},
+			{Addr: 0x18, Write: []byte{0xc3, 0x6, 0x26, 0x46, 0x66, 0x86}},
+		},
+	}
+	d, err := New(&bus, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if s := d.String(); s != "ds248x" {
+		t.Fatal(s)
+	}
+	if err := bus.Close(); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestNew_opts(t *testing.T) {
+	bus := i2ctest.Playback{
+		Ops: []i2ctest.IO{
+			{Addr: 0x18, Write: []byte{0xf0}},
+			{Addr: 0x18, Write: []byte{0xe1, 0xf0}, Read: []byte{0x18}},
+			{Addr: 0x18, Write: []byte{0xd2, 0xe1}, Read: []byte{0x1}},
+			{Addr: 0x18, Write: []byte{0xe1, 0xb4}},
+			{Addr: 0x18, Write: []byte{0xc3, 0x6, 0x26, 0x46, 0x66, 0x86}},
+		},
+	}
+	opts := &Opts{Addr: 0x18}
+	if _, err := New(&bus, opts); err != nil {
+		t.Fatal(err)
+	}
+	if err := bus.Close(); err != nil {
+		t.Fatal(err)
+	}
 }
 
 /* Commented out in order not to import periph/host, need to move to smoke test