diff --git a/aht20/aht20.go b/aht20/aht20.go
index 8bab0d9..5d6cf3c 100644
--- a/aht20/aht20.go
+++ b/aht20/aht20.go
@@ -70,10 +70,10 @@ func NewI2C(b i2c.Bus, opts *Opts) (*Dev, error) {
 		d.opts.MeasurementWaitInterval = 10 * time.Millisecond
 	}
 
-	if err, initialized := d.isInitialized(); err != nil {
+	if err, initialized := d.IsInitialized(); err != nil {
 		return nil, fmt.Errorf("%w; could read sensor status", err)
 	} else if !initialized {
-		if err := d.initialize(); err != nil {
+		if err := d.Initialize(); err != nil {
 			return nil, fmt.Errorf("%w; could not calibrate sensor", err)
 		}
 	}
@@ -191,15 +191,17 @@ func (d *Dev) Halt() error {
 	return nil
 }
 
-func (d *Dev) isInitialized() (error, bool) {
-	var data byte
-	if err := d.d.Tx([]byte{cmdStatus}, []byte{data}); err != nil {
+// IsInitialized returns true if the sensor is initialized (calibrated)
+func (d *Dev) IsInitialized() (error, bool) {
+	data := make([]byte, 1)
+	if err := d.d.Tx([]byte{cmdStatus}, data); err != nil {
 		return err, false
 	}
-	return nil, data&bitInitialized == 1
+	return nil, (data[0] & bitInitialized) != 0
 }
 
-func (d *Dev) initialize() error {
+// Initialize calibrates the sensor. It takes 10ms.
+func (d *Dev) Initialize() error {
 	if err := d.d.Tx(argsInitialize, nil); err != nil {
 		return err
 	}
diff --git a/aht20/aht20_test.go b/aht20/aht20_test.go
new file mode 100644
index 0000000..3ef3a79
--- /dev/null
+++ b/aht20/aht20_test.go
@@ -0,0 +1,176 @@
+// Copyright 2024 The Periph Authors. All rights reserved.
+// Use of this source code is governed under the Apache License, Version 2.0
+// that can be found in the LICENSE file.
+
+package aht20
+
+import (
+	"periph.io/x/conn/v3/i2c"
+	"periph.io/x/conn/v3/i2c/i2ctest"
+	"periph.io/x/conn/v3/physic"
+	"testing"
+)
+
+const byteStatusInitialized = bitInitialized | 0x10
+
+func TestNewI2C(t *testing.T) {
+	type TestCase struct {
+		name string
+		ops  []i2ctest.IO
+	}
+
+	testCases := []TestCase{
+		{
+			name: "device already initialized",
+			ops: []i2ctest.IO{
+				// Read status
+				{Addr: deviceAddress, W: []byte{cmdStatus}, R: []byte{byteStatusInitialized}},
+			},
+		},
+		{
+			name: "device not initialized",
+			ops: []i2ctest.IO{
+				// Read status
+				{Addr: deviceAddress, W: []byte{cmdStatus}, R: []byte{0x00}},
+				// Initialize
+				{Addr: deviceAddress, W: argsInitialize},
+			},
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			bus := i2ctest.Playback{Ops: tc.ops}
+			if dev, err := NewI2C(&bus, nil); err != nil {
+				t.Fatal(err)
+			} else if dev == nil {
+				t.Fatal("expected device")
+			}
+		})
+	}
+}
+
+func TestDev_IsInitialized_true(t *testing.T) {
+	bus := i2ctest.Playback{
+		Ops: []i2ctest.IO{
+			// Read status
+			{Addr: deviceAddress, W: []byte{cmdStatus}, R: []byte{byteStatusInitialized}},
+		},
+	}
+	dev := Dev{d: &i2c.Dev{Bus: &bus, Addr: deviceAddress}, opts: DefaultOpts}
+	if err, initialized := dev.IsInitialized(); err != nil {
+		t.Fatal(err)
+	} else if !initialized {
+		t.Fatal("expected initialized")
+	}
+}
+
+func TestDev_IsInitialized_false(t *testing.T) {
+	bus := i2ctest.Playback{
+		Ops: []i2ctest.IO{
+			// Read status
+			{Addr: deviceAddress, W: []byte{cmdStatus}, R: []byte{0x00}},
+		},
+	}
+	dev := Dev{d: &i2c.Dev{Bus: &bus, Addr: deviceAddress}, opts: DefaultOpts}
+	if err, initialized := dev.IsInitialized(); err != nil {
+		t.Fatal(err)
+	} else if initialized {
+		t.Fatal("expected not initialized")
+	}
+}
+
+func TestDev_Initialize(t *testing.T) {
+	bus := i2ctest.Playback{
+		Ops: []i2ctest.IO{
+			// Initialize
+			{Addr: deviceAddress, W: argsInitialize},
+		},
+	}
+	dev := Dev{d: &i2c.Dev{Bus: &bus, Addr: deviceAddress}, opts: DefaultOpts}
+	if err := dev.Initialize(); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestDev_Sense_successful(t *testing.T) {
+	bus := i2ctest.Playback{
+		Ops: []i2ctest.IO{
+			// Trigger measurement
+			{Addr: deviceAddress, W: argsMeasure},
+			// Read measurement
+			{Addr: deviceAddress, R: []byte{byteStatusInitialized, 0x75, 0x52, 0x05, 0x8E, 0x40, 0x7F}},
+		},
+	}
+	dev := Dev{d: &i2c.Dev{Bus: &bus, Addr: deviceAddress}, opts: DefaultOpts}
+	e := physic.Env{}
+	if err := dev.Sense(&e); err != nil {
+		t.Fatal(err)
+	}
+	if expected := 19445800781*physic.NanoKelvin + physic.ZeroCelsius; e.Temperature != expected {
+		t.Fatalf("temperature %s(%d) != %s(%d)", expected, expected, e.Temperature, e.Temperature)
+	}
+	if expected := 4582824 * physic.TenthMicroRH; e.Humidity != expected {
+		t.Fatalf("humidity %s(%d) != %s(%d)", expected, expected, e.Humidity, e.Humidity)
+	}
+	if expected := 0 * physic.Pascal; e.Pressure != expected {
+		t.Fatalf("pressure %s(%d) != %s(%d)", expected, expected, e.Pressure, e.Pressure)
+	}
+	if err := bus.Close(); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestDev_Sense_error(t *testing.T) {
+	type TestCase struct {
+		name  string
+		data  []byte
+		error error
+	}
+
+	testCases := []TestCase{
+		{
+			name:  "data corrupt",
+			data:  []byte{byteStatusInitialized, 0x75, 0x52, 0x05, 0x8E, 0x40, 0x7E},
+			error: &DataCorruptionError{0x7F, 0x7E},
+		},
+		{
+			name:  "not initialized",
+			data:  []byte{0x00, 0x75, 0x52, 0x05, 0x8E, 0x40, 0x20},
+			error: &NotInitializedError{},
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			bus := i2ctest.Playback{
+				Ops: []i2ctest.IO{
+					// Trigger measurement
+					{Addr: deviceAddress, W: argsMeasure},
+					// Read measurement
+					{Addr: deviceAddress, R: tc.data},
+				},
+			}
+			dev := Dev{d: &i2c.Dev{Bus: &bus, Addr: deviceAddress}, opts: DefaultOpts}
+			e := physic.Env{}
+			if err := dev.Sense(&e); err == nil {
+				t.Fatal("expected error")
+			} else if err.Error() != tc.error.Error() {
+				t.Fatalf("expected error %s, got %s", tc.error, err)
+			}
+		})
+	}
+}
+
+func TestDev_SoftReset(t *testing.T) {
+	bus := i2ctest.Playback{
+		Ops: []i2ctest.IO{
+			// Soft reset
+			{Addr: deviceAddress, W: []byte{cmdSoftReset}},
+		},
+	}
+	dev := Dev{d: &i2c.Dev{Bus: &bus, Addr: deviceAddress}, opts: DefaultOpts}
+	if err := dev.SoftReset(); err != nil {
+		t.Fatal(err)
+	}
+}