diff --git a/Makefile b/Makefile
index 185374b..75c45a9 100644
--- a/Makefile
+++ b/Makefile
@@ -63,6 +63,8 @@ smoke-test:
 	@md5sum ./build/test.hex
 	tinygo build -size short -o ./build/test.hex -target=arduino-nano33 ./examples/hd44780i2c/main.go
 	@md5sum ./build/test.hex
+	tinygo build -size short -o ./build/test.hex -target=nano-33-ble ./examples/hts221/main.go
+	@md5sum ./build/test.hex
 	tinygo build -size short -o ./build/test.hex -target=microbit ./examples/hub75/main.go
 	@md5sum ./build/test.hex
 	tinygo build -size short -o ./build/test.hex -target=pyportal ./examples/ili9341/basic
@@ -212,7 +214,7 @@ DRIVERS = $(wildcard */)
 NOTESTS = build examples flash semihosting pcd8544 shiftregister st7789 microphone mcp3008 gps microbitmatrix \
 		hcsr04 ssd1331 ws2812 thermistor apa102 easystepper ssd1351 ili9341 wifinina shifter hub75 \
 		hd44780 buzzer ssd1306 espat l9110x st7735 bmi160 l293x dht keypad4x4 max72xx p1am tone tm1637 \
-		pcf8563 mcp2515 servo sdcard rtl8720dn image cmd i2csoft
+		pcf8563 mcp2515 servo sdcard rtl8720dn image cmd i2csoft hts221
 TESTS = $(filter-out $(addsuffix /%,$(NOTESTS)),$(DRIVERS))
 
 unit-test:
diff --git a/examples/hts221/main.go b/examples/hts221/main.go
new file mode 100644
index 0000000..0b48295
--- /dev/null
+++ b/examples/hts221/main.go
@@ -0,0 +1,36 @@
+package main
+
+import (
+	"machine"
+	"time"
+
+	"tinygo.org/x/drivers/hts221"
+)
+
+func main() {
+
+	machine.I2C1.Configure(machine.I2CConfig{
+		SCL:       machine.P0_15, // SCL1 on Nano 33 BLE Sense
+		SDA:       machine.P0_14, // SDA1 on Nano 33 BLE Sense
+		Frequency: machine.TWI_FREQ_400KHZ,
+	})
+
+	sensor := hts221.New(machine.I2C1)
+
+	if !sensor.Connected() {
+		println("HTS221 not connected!")
+		return
+	}
+
+	sensor.Configure() // power on and calibrate
+
+	for {
+
+		h, _ := sensor.ReadHumidity()
+		t, _ := sensor.ReadTemperature()
+		println("h =", float32(h)/100.0, "% / t =", float32(t)/1000.0, "*C")
+		time.Sleep(time.Second)
+
+	}
+
+}
diff --git a/hts221/hts221.go b/hts221/hts221.go
new file mode 100644
index 0000000..63f4385
--- /dev/null
+++ b/hts221/hts221.go
@@ -0,0 +1,178 @@
+// Package hts221 implements a driver for HTS221,
+// a capacitive digital sensor for relative humidity and temperature.
+//
+// Datasheet: https://www.st.com/resource/en/datasheet/hts221.pdf
+//
+package hts221
+
+import (
+	"errors"
+
+	"tinygo.org/x/drivers"
+)
+
+// Device wraps an I2C connection to a HTS221 device.
+type Device struct {
+	bus              drivers.I2C
+	Address          uint8
+	humiditySlope    float32
+	humidityZero     float32
+	temperatureSlope float32
+	temperatureZero  float32
+}
+
+// Connected returns whether HTS221 has been found.
+// It does a "who am I" request and checks the response.
+func (d *Device) Connected() bool {
+	data := []byte{0}
+	d.bus.ReadRegister(d.Address, HTS221_WHO_AM_I_REG, data)
+	return data[0] == 0xBC
+}
+
+// Configure sets up the HTS221 device for communication.
+func (d *Device) Configure() {
+	// read calibration data
+	d.calibration()
+	// activate device and use block data update mode
+	d.Power(true)
+}
+
+// Power is for turn on/off the HTS221 device
+func (d *Device) Power(status bool) {
+	data := []byte{0}
+	if status {
+		data[0] = 0x84
+	}
+	d.bus.WriteRegister(d.Address, HTS221_CTRL1_REG, data)
+}
+
+// ReadHumidity returns the relative humidity in percent * 100.
+// Returns an error if the device is not turned on.
+func (d *Device) ReadHumidity() (humidity int32, err error) {
+	err = d.waitForOneShot(0x02)
+	if err != nil {
+		return
+	}
+
+	// read data and calibrate
+	data := []byte{0, 0}
+	d.bus.ReadRegister(d.Address, HTS221_HUMID_OUT_REG, data[:1])
+	d.bus.ReadRegister(d.Address, HTS221_HUMID_OUT_REG+1, data[1:])
+	hValue := readInt(data[1], data[0])
+	hValueCalib := float32(hValue)*d.humiditySlope + d.humidityZero
+
+	return int32(hValueCalib * 100), nil
+}
+
+// ReadTemperature returns the temperature in celsius milli degrees (°C/1000).
+// Returns an error if the device is not turned on.
+func (d *Device) ReadTemperature() (temperature int32, err error) {
+	err = d.waitForOneShot(0x01)
+	if err != nil {
+		return
+	}
+
+	// read data and calibrate
+	data := []byte{0, 0}
+	d.bus.ReadRegister(d.Address, HTS221_TEMP_OUT_REG, data[:1])
+	d.bus.ReadRegister(d.Address, HTS221_TEMP_OUT_REG+1, data[1:])
+	tValue := readInt(data[1], data[0])
+	tValueCalib := float32(tValue)*d.temperatureSlope + d.temperatureZero
+
+	return int32(tValueCalib * 1000), nil
+}
+
+// Resolution sets the HTS221's resolution mode.
+// The higher resolutions are more accurate but comsume more power (see datasheet).
+// The number of averaged samples will be (h + 2) ^ 2, (t + 1) ^ 2
+//
+func (d *Device) Resolution(h uint8, t uint8) {
+	if h > 7 {
+		h = 3 // default
+	}
+	if t > 7 {
+		t = 3 // default
+	}
+	d.bus.WriteRegister(d.Address, HTS221_AV_CONF_REG, []byte{h<<3 | t})
+}
+
+// private functions
+
+// read factory calibration data
+func (d *Device) calibration() {
+	h0rH, h1rH := []byte{0}, []byte{0}
+	t0degC, t1degC := []byte{0}, []byte{0}
+	t1t0msb := []byte{0}
+	h0t0Out, h1t0Out := []byte{0, 0}, []byte{0, 0}
+	t0Out, t1Out := []byte{0, 0}, []byte{0, 0}
+
+	d.bus.ReadRegister(d.Address, HTS221_H0_rH_x2_REG, h0rH)
+	d.bus.ReadRegister(d.Address, HTS221_H1_rH_x2_REG, h1rH)
+	d.bus.ReadRegister(d.Address, HTS221_T0_degC_x8_REG, t0degC)
+	d.bus.ReadRegister(d.Address, HTS221_T1_degC_x8_REG, t1degC)
+	d.bus.ReadRegister(d.Address, HTS221_T1_T0_MSB_REG, t1t0msb)
+	d.bus.ReadRegister(d.Address, HTS221_H0_T0_OUT_REG, h0t0Out[:1])
+	d.bus.ReadRegister(d.Address, HTS221_H0_T0_OUT_REG+1, h0t0Out[1:])
+	d.bus.ReadRegister(d.Address, HTS221_H1_T0_OUT_REG, h1t0Out[:1])
+	d.bus.ReadRegister(d.Address, HTS221_H1_T0_OUT_REG+1, h1t0Out[1:])
+	d.bus.ReadRegister(d.Address, HTS221_T0_OUT_REG, t0Out[:1])
+	d.bus.ReadRegister(d.Address, HTS221_T0_OUT_REG+1, t0Out[1:])
+	d.bus.ReadRegister(d.Address, HTS221_T1_OUT_REG, t1Out[:1])
+	d.bus.ReadRegister(d.Address, HTS221_T1_OUT_REG+1, t1Out[1:])
+
+	h0rH_v := float32(h0rH[0]) / 2.0
+	h1rH_v := float32(h1rH[0]) / 2.0
+	t0degC_v := float32(readUint(t1t0msb[0]&0x03, t0degC[0])) / 8.0
+	t1degC_v := float32(readUint(t1t0msb[0]&0x0C>>2, t1degC[0])) / 8.0
+	h0t0Out_v := float32(readInt(h0t0Out[1], h0t0Out[0]))
+	h1t0Out_v := float32(readInt(h1t0Out[1], h1t0Out[0]))
+	t0Out_v := float32(readInt(t0Out[1], t0Out[0]))
+	t1Out_v := float32(readInt(t1Out[1], t1Out[0]))
+
+	d.humiditySlope = (h1rH_v - h0rH_v) / (h1t0Out_v - h0t0Out_v)
+	d.humidityZero = h0rH_v - d.humiditySlope*h0t0Out_v
+	d.temperatureSlope = (t1degC_v - t0degC_v) / (t1Out_v - t0Out_v)
+	d.temperatureZero = t0degC_v - d.temperatureSlope*t0Out_v
+}
+
+// wait and trigger one shot in block update
+func (d *Device) waitForOneShot(filter uint8) error {
+	data := []byte{0}
+
+	// check if the device is on
+	d.bus.ReadRegister(d.Address, HTS221_CTRL1_REG, data)
+	if data[0]&0x80 == 0 {
+		return errors.New("device is off, unable to query")
+	}
+
+	// wait until one shot (one conversion) is ready to go
+	data[0] = 1
+	for {
+		d.bus.ReadRegister(d.Address, HTS221_CTRL2_REG, data)
+		if data[0]&0x01 == 0 {
+			break
+		}
+	}
+
+	// trigger one shot
+	d.bus.WriteRegister(d.Address, HTS221_CTRL2_REG, []byte{0x01})
+
+	// wait until conversion completed
+	data[0] = 0
+	for {
+		d.bus.ReadRegister(d.Address, HTS221_STATUS_REG, data)
+		if data[0]&filter == filter {
+			break
+		}
+	}
+
+	return nil
+}
+
+func readUint(msb byte, lsb byte) uint16 {
+	return uint16(msb)<<8 | uint16(lsb)
+}
+
+func readInt(msb byte, lsb byte) int16 {
+	return int16(uint16(msb)<<8 | uint16(lsb))
+}
diff --git a/hts221/hts221_generic.go b/hts221/hts221_generic.go
new file mode 100644
index 0000000..c9a93cd
--- /dev/null
+++ b/hts221/hts221_generic.go
@@ -0,0 +1,13 @@
+// +build !nano_33_ble
+
+package hts221
+
+import "tinygo.org/x/drivers"
+
+// New creates a new HTS221 connection. The I2C bus must already be
+// configured.
+//
+// This function only creates the Device object, it does not touch the device.
+func New(bus drivers.I2C) Device {
+	return Device{bus: bus, Address: HTS221_ADDRESS}
+}
diff --git a/hts221/hts221_nano_33_ble.go b/hts221/hts221_nano_33_ble.go
new file mode 100644
index 0000000..7fb2e7b
--- /dev/null
+++ b/hts221/hts221_nano_33_ble.go
@@ -0,0 +1,28 @@
+// +build nano_33_ble
+
+package hts221
+
+import (
+	"machine"
+	"time"
+
+	"tinygo.org/x/drivers"
+)
+
+// New creates a new HTS221 connection. The I2C bus must already be
+// configured.
+//
+// This function only creates the Device object, it does not touch the device.
+func New(bus drivers.I2C) Device {
+	// turn on internal power pin (machine.P0_22) and I2C1 pullups power pin (machine.P1_00)
+	// and wait a moment.
+	ENV := machine.P0_22
+	ENV.Configure(machine.PinConfig{Mode: machine.PinOutput})
+	ENV.High()
+	R := machine.P1_00
+	R.Configure(machine.PinConfig{Mode: machine.PinOutput})
+	R.High()
+	time.Sleep(time.Millisecond * 10)
+
+	return Device{bus: bus, Address: HTS221_ADDRESS}
+}
diff --git a/hts221/registers.go b/hts221/registers.go
new file mode 100644
index 0000000..62a27a3
--- /dev/null
+++ b/hts221/registers.go
@@ -0,0 +1,27 @@
+package hts221
+
+const (
+
+	// I2C address
+	HTS221_ADDRESS = 0x5F
+
+	// control/status registers
+	HTS221_WHO_AM_I_REG  = 0x0F
+	HTS221_AV_CONF_REG   = 0x10
+	HTS221_CTRL1_REG     = 0x20
+	HTS221_CTRL2_REG     = 0x21
+	HTS221_STATUS_REG    = 0x27
+	HTS221_HUMID_OUT_REG = 0x28
+	HTS221_TEMP_OUT_REG  = 0x2A
+
+	// calibration registers
+	HTS221_H0_rH_x2_REG   = 0x30
+	HTS221_H1_rH_x2_REG   = 0x31
+	HTS221_T0_degC_x8_REG = 0x32
+	HTS221_T1_degC_x8_REG = 0x33
+	HTS221_T1_T0_MSB_REG  = 0x35
+	HTS221_H0_T0_OUT_REG  = 0x36
+	HTS221_H1_T0_OUT_REG  = 0x3A
+	HTS221_T0_OUT_REG     = 0x3C
+	HTS221_T1_OUT_REG     = 0x3E
+)