Add TI HDC302x Sensor Support (#83)

* Fix race conditions in test SenseContinuous()

Fixes #84

hdc302x/example_test.go

@@ -0,0 +1,41 @@
+// 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 hdc302x_test
+
+import (
+	"fmt"
+	"log"
+
+	"periph.io/x/conn/v3/i2c/i2creg"
+	"periph.io/x/conn/v3/physic"
+	"periph.io/x/devices/v3/hdc302x"
+	"periph.io/x/host/v3"
+)
+
+func Example() {
+	// Make sure periph is initialized.
+	if _, err := host.Init(); err != nil {
+		log.Fatal(err)
+	}
+	// Open default I²C bus.
+	bus, err := i2creg.Open("")
+	if err != nil {
+		log.Fatalf("failed to open I²C: %v", err)
+	}
+	defer bus.Close()
+
+	// Create the Sensor
+	sensor, err := hdc302x.NewI2C(bus, hdc302x.DefaultSensorAddress, hdc302x.RateFourHertz)
+	if err != nil {
+		log.Fatal(err)
+	}
+	// Take a reading
+	env := physic.Env{}
+	err = sensor.Sense(&env)
+	if err != nil {
+		log.Fatal(err)
+	}
+	fmt.Printf("Sensor Output: %s\n", env)
+}

hdc302x/hdc302x.go

@@ -0,0 +1,679 @@
+// 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.
+
+// This package provides a driver for the Texas Instruments HDC3021/3022
+// I2C Temperature/Humidity Sensors. This is a high accuracy sensor with
+// very good resolution.
+//
+// Datasheet
+//
+//	https://www.ti.com/lit/ds/symlink/hdc3022.pdf
+package hdc302x
+
+import (
+	"errors"
+	"fmt"
+	"math"
+	"sync"
+	"time"
+
+	"periph.io/x/conn/v3"
+	"periph.io/x/conn/v3/i2c"
+	"periph.io/x/conn/v3/physic"
+)
+
+type SampleRate uint16
+
+const (
+	// Constants for the sample rate to use for the measurements. The datasheet
+	// recommends not sampling more often than once per second to avoid self-heating
+	// of the sensor.
+	//
+	// Every other second
+	RateHalfHertz SampleRate = iota
+	// Sample 1x Second.
+	RateHertz
+	RateTwoHertz
+	RateFourHertz
+	Rate10Hertz
+)
+
+// Dev represents a hdc302x sensor.
+type Dev struct {
+	d          *i2c.Dev
+	shutdown   chan struct{}
+	mu         sync.Mutex
+	sampleRate SampleRate
+	halted     bool
+}
+
+// The alert function works with pairs of values Temperature/Humidity. A
+// Threshold is a set of humidity/temperature values defining an upper or
+// lower limit for alerts.
+type Threshold struct {
+	Humidity    physic.RelativeHumidity
+	Temperature physic.Temperature
+}
+
+// For alert and clear, there is a pair of temperatures. For example,
+// a low alert value, and a clear low alert value. There's a value
+// for each measurement parameter.
+type ThresholdPair struct {
+	Low  Threshold
+	High Threshold
+}
+
+type StatusWord uint16
+
+const (
+	// Status flags returned by ReadStatus()
+	StatusActiveAlerts  StatusWord = 1 << 15
+	StatusHeaterEnabled StatusWord = 1 << 13
+	// Mirrored on the alert pin.
+	StatusRHTrackingAlert StatusWord = 1 << 11
+	// Also reflected on alert pin
+	StatusTempTrackingAlert     StatusWord = 1 << 10
+	StatusRHHighTrackingAlert   StatusWord = 1 << 9
+	StatusRHLowTrackingAlert    StatusWord = 1 << 8
+	StatusTempHighTrackingAlert StatusWord = 1 << 7
+	StatusTempLowTrackingAlert  StatusWord = 1 << 6
+	StatusDeviceReset           StatusWord = 1 << 4
+	// Set if there was a CRC error on the last write command.
+	StatusLastWriteCRCFailure StatusWord = 1 << 0
+)
+
+// Configuration provides information about the running device's config.
+type Configuration struct {
+	// Device unique ID. Read-Only
+	SerialNumber int64
+	// Numeric vendor ID. Read-Only
+	VendorID uint16
+	// Status Word. Refer to the Status* constants above, and the datasheet for
+	// usage.
+	Status StatusWord
+	// refer to the Rate constants. Read-Only
+	SampleRate SampleRate
+	// Offset for RH calculation. Note that these offsets are approximate,
+	// so a request to set the offset to -5%rH may result in an offset of
+	// -4.8%rH. This is an artifact of the device's offset implementation.
+	// Refer to the datasheet for more information.
+	HumidityOffset physic.RelativeHumidity
+	// Offset for Temp result. Note that the data sheet states this is not
+	// used in the RH calculation.
+	TemperatureOffset physic.Temperature
+
+	// High/Low thresholds for triggering alerts. As with the offsets,
+	// written values are not precise.
+	AlertThresholds ThresholdPair
+	// High/Low threshold for clearing alerts.
+	ClearThresholds ThresholdPair
+}
+
+const (
+	// The default i2c bus address for this device.
+	DefaultSensorAddress uint16 = 0x44
+)
+
+type HeaterPower uint16
+
+const (
+	// Constants for setting the heater's power setting.
+	PowerFull    HeaterPower = 0x3fff
+	PowerHalf    HeaterPower = 0x03ff
+	PowerQuarter HeaterPower = 0x9f
+	PowerOff     HeaterPower = 0
+)
+
+type devCommand []byte
+
+// Sample Rate commands
+var measure2Seconds = devCommand{0x20, 0x32}
+var measureSecond = devCommand{0x21, 0x30}
+var measure2xSecond = devCommand{0x22, 0x36}
+var measure4xSecond = devCommand{0x23, 0x34}
+var measure10xSecond = devCommand{0x27, 0x37}
+
+var sampleRateCommands = []devCommand{measure2Seconds, measureSecond, measure2xSecond, measure4xSecond, measure10xSecond}
+var sampleRateDurations = []time.Duration{2 * time.Second, time.Second, 500 * time.Millisecond, 250 * time.Millisecond, 100 * time.Millisecond}
+
+// Other device commands
+var clearStatus = devCommand{0x30, 0x41}
+var disableHeater = devCommand{0x30, 0x66}
+var enableHeater = devCommand{0x30, 0x6d}
+var read = devCommand{0xe0, 0x0}
+var readSetHeater = devCommand{0x30, 0x6e}
+var readSetOffsets = devCommand{0xa0, 0x04}
+var readStatus = devCommand{0xf3, 0x2d}
+var readVendorID = devCommand{0x37, 0x81}
+var reset = devCommand{0x30, 0xa2}
+var stopContinuousReadings = devCommand{0x30, 0x93}
+
+// read/write alert threshold commands.
+var readLowAlertThresholds = devCommand{0xe1, 0x02}
+var readHighAlertThresholds = devCommand{0xe1, 0x1f}
+var readLowClearThresholds = devCommand{0xe1, 0x09}
+var readHighClearThresholds = devCommand{0xe1, 0x14}
+var writeLowAlertThresholds = devCommand{0x61, 0x00}
+var writeHighAlertThresholds = devCommand{0x61, 0x1d}
+var writeLowClearThresholds = devCommand{0x61, 0x0b}
+var writeHighClearThresholds = devCommand{0x61, 0x16}
+
+var errInvalidCRC = errors.New("hdc302x: invalid crc")
+
+const (
+	// Magic numbers for count to value conversions.
+	temperatureOffset float64 = -45.0
+	temperatureScalar float64 = 175.0
+	humidityScalar    float64 = 100.0
+	scaleDivisor      float64 = 65535.0
+)
+
+// NewI2C returns a new HDC302x sensor using the specified bus, address, and
+// sample rate.
+func NewI2C(b i2c.Bus, addr uint16, sampleRate SampleRate) (*Dev, error) {
+	dev := &Dev{d: &i2c.Dev{Bus: b, Addr: addr}, shutdown: nil, sampleRate: sampleRate}
+	return dev, dev.start()
+}
+
+// send continuous measurement start command.
+func (dev *Dev) start() error {
+	if err := dev.d.Tx(sampleRateCommands[dev.sampleRate], nil); err != nil {
+		return fmt.Errorf("hdc302x: init %w", err)
+	}
+	// Sleep for a minimum of one sample acquisition period. If you
+	// read before a sample has acquired, you get remote I/O error.
+	time.Sleep(sampleRateDurations[dev.sampleRate])
+	dev.halted = false
+	return nil
+}
+
+// Convert the raw count to a temperature.
+func countToTemperature(bytes []byte) physic.Temperature {
+	count := (uint16(bytes[0]) << 8) | uint16(bytes[1])
+	f := float64(count)/float64(scaleDivisor)*temperatureScalar + temperatureOffset
+	t := physic.ZeroCelsius + physic.Temperature(f*float64(physic.Celsius))
+	return t
+}
+
+// convert the raw count to a humidity value.
+func countToHumidity(bytes []byte) physic.RelativeHumidity {
+	count := (uint16(bytes[0]) << 8) | uint16(bytes[1])
+	f := float64(count) / float64(scaleDivisor) * humidityScalar
+	return physic.RelativeHumidity(f * float64(physic.PercentRH))
+}
+
+func crc8(bytes []byte) byte {
+	var crc byte = 0xff
+	for _, val := range bytes {
+		crc ^= val
+		for range 8 {
+			if (crc & 0x80) == 0 {
+				crc <<= 1
+			} else {
+				crc = (byte)((crc << 1) ^ 0x31)
+			}
+		}
+	}
+	return crc
+}
+
+// Halt shuts down the device. If a SenseContinuous operation is in progress,
+// its aborted. Implements conn.Resource
+func (dev *Dev) Halt() error {
+	dev.mu.Lock()
+	defer dev.mu.Unlock()
+	if dev.shutdown != nil {
+		close(dev.shutdown)
+	}
+	var err error
+	if !dev.halted {
+		dev.halted = true
+		err = dev.d.Tx(stopContinuousReadings, nil)
+	}
+	return err
+}
+
+// Sense reads temperature and humidity from the device and writes the value to
+// the specified env variable. Implements physic.SenseEnv.
+func (dev *Dev) Sense(env *physic.Env) error {
+	env.Temperature = 0
+	env.Pressure = 0
+	env.Humidity = 0
+	res := make([]byte, 6)
+	dev.mu.Lock()
+	defer dev.mu.Unlock()
+	if dev.halted {
+		if err := dev.start(); err != nil {
+			return err
+		}
+	}
+	if err := dev.d.Tx(read, res); err != nil {
+		return fmt.Errorf("hdc302x: %w", err)
+	}
+	if crc8(res[:2]) != res[2] || crc8(res[3:5]) != res[5] {
+		return errInvalidCRC
+	}
+	env.Temperature = countToTemperature(res)
+	env.Humidity = countToHumidity(res[3:])
+	return nil
+}
+
+func temperatureToFloat64(temp physic.Temperature) float64 {
+	return float64(temp) / float64(physic.Celsius)
+}
+
+func humidityToFloat64(humidity physic.RelativeHumidity) float64 {
+	return float64(humidity) / float64(physic.PercentRH)
+}
+
+// SenseContinuous continuously reads from the device and writes the value to
+// the returned channel. Implements physic.SenseEnv. To terminate the
+// continuous read, call Halt().
+//
+// If interval is less than the device sample period, an error is returned.
+func (dev *Dev) SenseContinuous(interval time.Duration) (<-chan physic.Env, error) {
+
+	if dev.shutdown != nil {
+		return nil, errors.New("hdc302x: SenseContinuous already running")
+	}
+
+	if interval < sampleRateDurations[dev.sampleRate] {
+		return nil, errors.New("hdc302x: sample interval is < device sample rate")
+	}
+
+	dev.shutdown = make(chan struct{})
+	chResult := make(chan physic.Env, 16)
+	go func(ch chan physic.Env) {
+		ticker := time.NewTicker(interval)
+		defer ticker.Stop()
+		defer close(ch)
+		for {
+			select {
+			case <-dev.shutdown:
+				dev.shutdown = nil
+				return
+			case <-ticker.C:
+				env := physic.Env{}
+				if err := dev.Sense(&env); err == nil {
+					ch <- env
+				}
+			}
+		}
+	}(chResult)
+	return chResult, nil
+}
+
+// Precision returns the sensor's precision, or minimum value between steps the
+// device can measure. Refer to the datasheet for information on limits and
+// accuracy.
+func (dev *Dev) Precision(env *physic.Env) {
+	env.Temperature = physic.Temperature(math.Round(temperatureScalar / scaleDivisor * float64(physic.Celsius)))
+	env.Humidity = physic.RelativeHumidity(math.Round((float64(physic.PercentRH) * humidityScalar) / float64(scaleDivisor)))
+	env.Pressure = 0
+}
+
+func (dev *Dev) readSerialNumber() int64 {
+	var result int64
+	cmd := []byte{0x36, 0x83}
+	r := make([]byte, 3)
+	// this is a 6 byte value read in 3 parts
+	for range 3 {
+		err := dev.d.Tx(cmd, r)
+		if err != nil || (crc8(r[:2]) != r[2]) {
+			return result
+		}
+		result = result<<16 | (int64(r[0])<<8 | int64(r[1]))
+		cmd[1] += 1 // Increment the register to the next one.
+	}
+	return result
+}
+
+// read the alert / clear threshold values from the device.
+func (dev *Dev) readAlertValues(cfg *Configuration) error {
+
+	// Pair
+	// 	Low
+	//		Temp
+	//		Humidity
+	//	High
+	//		Temp
+	//		Humidity
+
+	var cmds = []devCommand{readLowAlertThresholds, readHighAlertThresholds, readLowClearThresholds, readHighClearThresholds}
+	var pairs = [2]*ThresholdPair{&cfg.AlertThresholds, &cfg.ClearThresholds}
+	var threshold *Threshold
+
+	r := make([]byte, 3)
+
+	for ix, cmd := range cmds {
+		pair := pairs[ix>>1]
+		if ix%2 == 0 {
+			threshold = &pair.Low
+		} else {
+			threshold = &pair.High
+		}
+
+		err := dev.d.Tx(cmd, r)
+		if err != nil {
+			return err
+		}
+		if crc8(r[:2]) != r[2] {
+			return errInvalidCRC
+		}
+		wValue := uint16(r[0])<<8 | uint16(r[1])
+		// The alert value is returned as a 16 bit words, where bits 0-8 are the
+		// Temperature value, and bits 9-15 are the Humidity. The temperature
+		// bits correspond to bits 7-15 of the temperature, and bits 9-15 of the
+		// humidity. Refer to the datasheet.
+		temp := &threshold.Temperature
+		humidity := &threshold.Humidity
+		*temp = physic.Temperature(((float64(uint16(wValue<<7)) * temperatureScalar) / scaleDivisor) * float64(physic.Celsius))
+		*humidity = physic.RelativeHumidity(((float64(wValue&0xfe00) * humidityScalar) / scaleDivisor) * float64(physic.PercentRH))
+	}
+
+	return nil
+}
+
+// readOffsets returns temperature/humidity offset values stored to the device.
+func (dev *Dev) readOffsets(cfg *Configuration) error {
+	r := make([]byte, 3)
+	if err := dev.d.Tx(readSetOffsets, r); err != nil {
+		return fmt.Errorf("hdc302x: %w", err)
+	}
+	if crc8(r[:2]) != r[2] {
+		return errInvalidCRC
+	}
+
+	// The result comes back as the humidity offset, followed by
+	// the temperature offset. The offsets are computed by summing
+	// the bits and applying the partial algorithm.
+
+	h := uint16((r[0] & 0x7f)) << 7
+	t := uint16((r[1] & 0x7f)) << 6
+	rh := float64(h) / scaleDivisor * humidityScalar
+	temp := (float64(t) * temperatureScalar) / scaleDivisor
+
+	if r[0]&0x80 == 0x00 {
+		rh *= -1.0
+	}
+	cfg.HumidityOffset = physic.RelativeHumidity(rh * float64(physic.PercentRH))
+
+	if r[1]&0x80 == 0x00 {
+		temp *= -1.0
+	}
+	cfg.TemperatureOffset = physic.Temperature(temp * float64(physic.Celsius))
+
+	return nil
+}
+
+func (dev *Dev) readVendorID() (uint16, error) {
+	r := make([]byte, 3)
+	err := dev.d.Tx(readVendorID, r)
+	if err == nil {
+		vid := uint16(r[0])<<8 | uint16(r[1])
+		return vid, nil
+	}
+	return 0, err
+}
+
+// ReadStatus returns the device's status word, and if successful, clears the
+// status. Refer to the Status* constants and the datasheet for interpretation.
+func (dev *Dev) ReadStatus() (StatusWord, error) {
+	r := make([]byte, 3)
+	if err := dev.d.Tx(readStatus, r); err != nil {
+		return 0, err
+	}
+	if crc8(r[:2]) != r[2] {
+		return 0, errInvalidCRC
+	}
+	_ = dev.d.Tx(clearStatus, nil)
+	return StatusWord(r[0])<<8 | StatusWord(r[1]), nil
+}
+
+// Return the device's configuration settings. Includes alert values, offset
+// values, and other information about the device.
+func (dev *Dev) Configuration() (*Configuration, error) {
+	cfg := &Configuration{SampleRate: dev.sampleRate}
+	cfg.SerialNumber = dev.readSerialNumber()
+	err := dev.readOffsets(cfg)
+	if err != nil {
+		return cfg, err
+	}
+	if cfg.VendorID, err = dev.readVendorID(); err != nil {
+		return cfg, err
+	}
+	if cfg.Status, err = dev.ReadStatus(); err != nil {
+		return cfg, err
+	}
+
+	err = dev.readAlertValues(cfg)
+
+	return cfg, err
+}
+
+// setOffsets writes temperature and humidity offsets to the device.
+// Refer to the datasheet for information on offsets. The critical
+// thing to know is that the smallest offsets are ~0.2%RH, and ~
+// 0.2 degrees C.
+func (dev *Dev) setOffsets(cfg *Configuration) error {
+	var w = []byte{readSetOffsets[0],
+		readSetOffsets[1],
+		computeHumidityOffsetByte(cfg.HumidityOffset),
+		computeTemperatureOffsetByte(cfg.TemperatureOffset),
+		0,
+	}
+	w[4] = crc8(w[2:4])
+	return dev.d.Tx(w, nil)
+}
+
+// Refer to the datasheet. Essentially, the offsets are only a specific set of
+// bit ranges.
+func computeTemperatureOffsetByte(temp physic.Temperature) byte {
+	var res byte
+	fTemp := temperatureToFloat64(temp)
+	if fTemp >= 0 {
+		res |= 0x80
+	} else {
+		fTemp *= -1.0
+	}
+	for bit := 12; bit > 5; bit-- {
+		offset := (float64(int64(1)<<bit) * temperatureScalar) / scaleDivisor
+		if fTemp >= offset {
+			fTemp -= offset
+			res |= (1 << (bit - 6))
+		}
+	}
+	return res
+}
+
+func computeHumidityOffsetByte(humidity physic.RelativeHumidity) byte {
+	var res byte
+	fHumidity := humidityToFloat64(humidity)
+	if fHumidity >= 0 {
+		res |= 0x80
+	} else {
+		fHumidity *= -1.0
+	}
+	for bit := 13; bit > 6; bit-- {
+		offset := (float64(int64(1)<<bit) * humidityScalar) / scaleDivisor
+		if fHumidity >= offset {
+			fHumidity -= offset
+			res |= (1 << (bit - 7))
+		}
+	}
+	return res
+}
+
+// Reset performs a soft-reset of the device.
+func (dev *Dev) Reset() error {
+	dev.mu.Lock()
+	defer dev.mu.Unlock()
+	err := dev.d.Tx(reset, nil)
+	time.Sleep(time.Second)
+	return err
+}
+
+// setThreshold sets a threshold pair for either alert, or clear alert.
+// if typeAlert is true, it indicates the pair type is alert, otherwise
+// it's clear alert.
+func (dev *Dev) setThresholds(typeAlert bool, tp *ThresholdPair) error {
+	var cmds = [][]devCommand{{writeLowAlertThresholds, writeHighAlertThresholds},
+		{writeLowClearThresholds, writeHighClearThresholds}}
+
+	pair := 1
+	if typeAlert {
+		pair = 0
+	}
+	var th *Threshold
+	for ix := range 2 {
+		if ix == 0 {
+			th = &tp.Low
+		} else {
+			th = &tp.High
+		}
+		temp := temperatureToFloat64(th.Temperature)
+		tempBits := uint16(0)
+		for bit := 15; bit >= 0; bit-- {
+			bitVal := (float64(uint16(1<<bit)) * temperatureScalar) / scaleDivisor
+			if temp >= bitVal {
+				temp -= bitVal
+				tempBits |= (1 << bit)
+			}
+		}
+		humidity := humidityToFloat64(th.Humidity)
+		humBits := uint16(0)
+		for bit := 15; bit >= 0; bit-- {
+			bitVal := (float64(uint16(1<<bit)) * humidityScalar) / scaleDivisor
+			if humidity >= bitVal {
+				humidity -= bitVal
+				humBits |= (1 << bit)
+			}
+		}
+		wval := uint16(0)
+		wval = (humBits & 0xfe00) | tempBits>>7
+		w := []byte{cmds[pair][ix][0], cmds[pair][ix][1], byte(wval >> 8), byte(wval & 0xff), 0}
+		w[4] = crc8(w[2:4])
+		err := dev.d.Tx(w, nil)
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+// SetConfiguration takes a modified configuration struct and
+// applies it to the device.
+func (dev *Dev) SetConfiguration(cfg *Configuration) error {
+	_ = dev.Halt()
+	dev.mu.Lock()
+	defer dev.mu.Unlock()
+	current, err := dev.Configuration()
+	if err != nil {
+		return err
+	}
+	if current.HumidityOffset != cfg.HumidityOffset || current.TemperatureOffset != cfg.TemperatureOffset {
+		if err := dev.setOffsets(cfg); err != nil {
+			return err
+		}
+	}
+
+	if !current.AlertThresholds.Equals(&cfg.AlertThresholds) {
+		if err := dev.setThresholds(true, &cfg.AlertThresholds); err != nil {
+			return err
+		}
+	}
+
+	if !current.ClearThresholds.Equals(&cfg.ClearThresholds) {
+		if err := dev.setThresholds(false, &cfg.ClearThresholds); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// The hdc302x sensors have a built in heater element for operating in environments
+// where the humidity/temperature level is condensing. SetHeater allows you to turn
+// the heater element on and off at specified power levels.  Refer to the datasheet
+// for instructions on how the heater can be used in those environments.
+func (dev *Dev) SetHeater(powerLevel HeaterPower) error {
+	if powerLevel > PowerFull {
+		return fmt.Errorf("hdc302x: invalid value for powerLevel: 0x%x", powerLevel)
+	}
+	if powerLevel == PowerOff {
+		return dev.d.Tx(disableHeater, nil)
+	}
+	var setValue = []byte{readSetHeater[0],
+		readSetHeater[1],
+		byte((powerLevel >> 8) & 0xff),
+		byte(powerLevel & 0xff),
+		0}
+	setValue[4] = crc8(setValue[2:4])
+	err := dev.d.Tx(setValue, nil)
+	if err != nil {
+		return err
+	}
+	return dev.d.Tx(enableHeater, nil)
+}
+
+func (dev *Dev) String() string {
+	return fmt.Sprintf("hdc302x: %s", dev.d.String())
+}
+
+func (cfg *Configuration) String() string {
+	return fmt.Sprintf(`{
+		SerialNumber: 0x%x, 
+		VendorID: 0x%x,
+		Status: 0x%x,
+		SampleRate: %d,
+		HumidityOffset: %s,
+		TemperatureOffset: %s,
+		AlertThresholds: %s,
+		ClearThresholds: %s
+		}`,
+		cfg.SerialNumber,
+		cfg.VendorID,
+		cfg.Status,
+		cfg.SampleRate,
+		cfg.HumidityOffset,
+		cfg.TemperatureOffset+physic.ZeroCelsius,
+		&cfg.AlertThresholds,
+		&cfg.ClearThresholds)
+}
+
+func (t *Threshold) String() string {
+	return fmt.Sprintf("{ Humidity: %s, Temperature: %s }", t.Humidity, t.Temperature+physic.ZeroCelsius)
+}
+
+func (tp *ThresholdPair) String() string {
+	return fmt.Sprintf("{ Low: %s, High: %s }",
+		&tp.Low,
+		&tp.High)
+}
+
+func (t *Threshold) Equals(tCompare *Threshold) bool {
+	return t.Temperature == tCompare.Temperature && t.Humidity == tCompare.Humidity
+}
+
+// For thresholds, you can only set a truncated value. For temperature, that means
+// the 9 high bits, and for humidity, the 7 high bits. This means a comparison of
+// a written value with the resulting value can be off. This method encapsulates
+// the comparison of a threshold pair to make sure they're approximately equal.
+func (t *Threshold) ApproximatelyEquals(tCompare *Threshold) bool {
+	t1 := temperatureToFloat64(t.Temperature)
+	h1 := humidityToFloat64(t.Humidity)
+	t2 := temperatureToFloat64(tCompare.Temperature)
+	h2 := humidityToFloat64(tCompare.Humidity)
+	tLimit := float64(uint16(1<<8)) * temperatureScalar / scaleDivisor
+	hLimit := float64(uint16(1<<9)) * humidityScalar / scaleDivisor
+	return math.Abs(t1-t2) < tLimit &&
+		math.Abs(h1-h2) < hLimit
+}
+
+func (tp *ThresholdPair) Equals(tpCompare *ThresholdPair) bool {
+	return tp.Low.Equals(&tpCompare.Low) && tp.High.Equals(&tpCompare.High)
+}
+
+var _ conn.Resource = &Dev{}
+var _ physic.SenseEnv = &Dev{}

hdc302x/hdc302x_test.go

@@ -0,0 +1,620 @@
+// 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 hdc302x
+
+import (
+	"fmt"
+	"math"
+	"os"
+	"sync"
+	"sync/atomic"
+	"testing"
+	"time"
+
+	"periph.io/x/conn/v3/i2c"
+	"periph.io/x/conn/v3/i2c/i2creg"
+	"periph.io/x/conn/v3/i2c/i2ctest"
+	"periph.io/x/conn/v3/physic"
+	"periph.io/x/host/v3"
+)
+
+var bus i2c.Bus
+var liveDevice bool
+
+// Playback values for a single sense operation.
+var pbSense = []i2ctest.IO{
+	{Addr: DefaultSensorAddress, W: []uint8{0x23, 0x34}},
+	// 26.621 C, 23.2%RH
+	{Addr: DefaultSensorAddress, W: []uint8{0xe0, 0x0}, R: []uint8{0x68, 0xc5, 0x51, 0x3b, 0x82, 0x31}},
+}
+
+// Playback for heater testing.
+var pbHeater = []i2ctest.IO{
+	{Addr: DefaultSensorAddress, W: []uint8{0x23, 0x34}},
+	{Addr: DefaultSensorAddress, W: []uint8{0xe0, 0x0}, R: []uint8{0x64, 0x93, 0x3d, 0x45, 0x3a, 0x61}},
+	{Addr: DefaultSensorAddress, W: []uint8{0x30, 0x6e, 0x3f, 0xff, 0x6}},
+	{Addr: DefaultSensorAddress, W: []uint8{0x30, 0x6d}},
+	{Addr: DefaultSensorAddress, W: []uint8{0xe0, 0x0}, R: []uint8{0x9d, 0xb1, 0x2, 0x9, 0xc6, 0xa3}},
+	{Addr: DefaultSensorAddress, W: []uint8{0x30, 0x66}}}
+
+// Playback for modifying configuration.
+var pbConfiguration = []i2ctest.IO{
+	{Addr: DefaultSensorAddress, W: []uint8{0x23, 0x34}},
+	{Addr: DefaultSensorAddress, W: []uint8{0x36, 0x83}, R: []uint8{0xc2, 0x95, 0x3e}},
+	{Addr: DefaultSensorAddress, W: []uint8{0x36, 0x84}, R: []uint8{0xb1, 0x49, 0x51}},
+	{Addr: DefaultSensorAddress, W: []uint8{0x36, 0x85}, R: []uint8{0x15, 0x21, 0x2f}},
+	{Addr: DefaultSensorAddress, W: []uint8{0xa0, 0x4}, R: []uint8{0x80, 0x80, 0xd8}},
+	{Addr: DefaultSensorAddress, W: []uint8{0x37, 0x81}, R: []uint8{0x30, 0x0, 0x33}},
+	{Addr: DefaultSensorAddress, W: []uint8{0xf3, 0x2d}, R: []uint8{0x0, 0x0, 0x81}},
+	{Addr: DefaultSensorAddress, W: []uint8{0x30, 0x41}},
+	{Addr: DefaultSensorAddress, W: []uint8{0xe1, 0x2}, R: []uint8{0x34, 0x66, 0xad}},
+	{Addr: DefaultSensorAddress, W: []uint8{0xe1, 0x1f}, R: []uint8{0xcd, 0x33, 0xfd}},
+	{Addr: DefaultSensorAddress, W: []uint8{0xe1, 0x9}, R: []uint8{0x38, 0x69, 0x37}},
+	{Addr: DefaultSensorAddress, W: []uint8{0xe1, 0x14}, R: []uint8{0xc9, 0x2d, 0x22}}}
+
+// playback for offset modification
+var pbOffsets = []i2ctest.IO{
+	{Addr: DefaultSensorAddress, W: []uint8{0x23, 0x34}},
+	{Addr: DefaultSensorAddress, W: []uint8{0xe0, 0x0}, R: []uint8{0x70, 0x90, 0x83, 0x42, 0x10, 0x92}},
+	{Addr: DefaultSensorAddress, W: []uint8{0x36, 0x83}, R: []uint8{0xc2, 0x95, 0x3e}},
+	{Addr: DefaultSensorAddress, W: []uint8{0x36, 0x84}, R: []uint8{0xb1, 0x49, 0x51}},
+	{Addr: DefaultSensorAddress, W: []uint8{0x36, 0x85}, R: []uint8{0x15, 0x21, 0x2f}},
+	{Addr: DefaultSensorAddress, W: []uint8{0xa0, 0x4}, R: []uint8{0x19, 0xba, 0x48}},
+	{Addr: DefaultSensorAddress, W: []uint8{0x37, 0x81}, R: []uint8{0x30, 0x0, 0x33}},
+	{Addr: DefaultSensorAddress, W: []uint8{0xf3, 0x2d}, R: []uint8{0x0, 0x0, 0x81}},
+	{Addr: DefaultSensorAddress, W: []uint8{0x30, 0x41}},
+	{Addr: DefaultSensorAddress, W: []uint8{0xe1, 0x2}, R: []uint8{0x34, 0x66, 0xad}},
+	{Addr: DefaultSensorAddress, W: []uint8{0xe1, 0x1f}, R: []uint8{0xcd, 0x33, 0xfd}},
+	{Addr: DefaultSensorAddress, W: []uint8{0xe1, 0x9}, R: []uint8{0x38, 0x69, 0x37}},
+	{Addr: DefaultSensorAddress, W: []uint8{0xe1, 0x14}, R: []uint8{0xc9, 0x2d, 0x22}},
+	{Addr: DefaultSensorAddress, W: []uint8{0x30, 0x93}},
+	{Addr: DefaultSensorAddress, W: []uint8{0x36, 0x83}, R: []uint8{0xc2, 0x95, 0x3e}},
+	{Addr: DefaultSensorAddress, W: []uint8{0x36, 0x84}, R: []uint8{0xb1, 0x49, 0x51}},
+	{Addr: DefaultSensorAddress, W: []uint8{0x36, 0x85}, R: []uint8{0x15, 0x21, 0x2f}},
+	{Addr: DefaultSensorAddress, W: []uint8{0xa0, 0x4}, R: []uint8{0x19, 0xba, 0x48}},
+	{Addr: DefaultSensorAddress, W: []uint8{0x37, 0x81}, R: []uint8{0x30, 0x0, 0x33}},
+	{Addr: DefaultSensorAddress, W: []uint8{0xf3, 0x2d}, R: []uint8{0x0, 0x0, 0x81}},
+	{Addr: DefaultSensorAddress, W: []uint8{0x30, 0x41}},
+	{Addr: DefaultSensorAddress, W: []uint8{0xe1, 0x2}, R: []uint8{0x34, 0x66, 0xad}},
+	{Addr: DefaultSensorAddress, W: []uint8{0xe1, 0x1f}, R: []uint8{0xcd, 0x33, 0xfd}},
+	{Addr: DefaultSensorAddress, W: []uint8{0xe1, 0x9}, R: []uint8{0x38, 0x69, 0x37}},
+	{Addr: DefaultSensorAddress, W: []uint8{0xe1, 0x14}, R: []uint8{0xc9, 0x2d, 0x22}},
+	{Addr: DefaultSensorAddress, W: []uint8{0xa0, 0x4, 0x32, 0xf4, 0xac}},
+	{Addr: DefaultSensorAddress, W: []uint8{0x36, 0x83}, R: []uint8{0xc2, 0x95, 0x3e}},
+	{Addr: DefaultSensorAddress, W: []uint8{0x36, 0x84}, R: []uint8{0xb1, 0x49, 0x51}},
+	{Addr: DefaultSensorAddress, W: []uint8{0x36, 0x85}, R: []uint8{0x15, 0x21, 0x2f}},
+	{Addr: DefaultSensorAddress, W: []uint8{0xa0, 0x4}, R: []uint8{0x32, 0xf4, 0xac}},
+	{Addr: DefaultSensorAddress, W: []uint8{0x37, 0x81}, R: []uint8{0x30, 0x0, 0x33}},
+	{Addr: DefaultSensorAddress, W: []uint8{0xf3, 0x2d}, R: []uint8{0x0, 0x0, 0x81}},
+	{Addr: DefaultSensorAddress, W: []uint8{0x30, 0x41}},
+	{Addr: DefaultSensorAddress, W: []uint8{0xe1, 0x2}, R: []uint8{0x34, 0x66, 0xad}},
+	{Addr: DefaultSensorAddress, W: []uint8{0xe1, 0x1f}, R: []uint8{0xcd, 0x33, 0xfd}},
+	{Addr: DefaultSensorAddress, W: []uint8{0xe1, 0x9}, R: []uint8{0x38, 0x69, 0x37}},
+	{Addr: DefaultSensorAddress, W: []uint8{0xe1, 0x14}, R: []uint8{0xc9, 0x2d, 0x22}},
+	{Addr: DefaultSensorAddress, W: []uint8{0x23, 0x34}},
+	{Addr: DefaultSensorAddress, W: []uint8{0xe0, 0x0}, R: []uint8{0x7f, 0x28, 0x1c, 0x37, 0x8d, 0xab}},
+	{Addr: DefaultSensorAddress, W: []uint8{0x30, 0xa2}}}
+
+var pbAlerts = []i2ctest.IO{
+	{Addr: DefaultSensorAddress, W: []uint8{0x23, 0x34}},
+	{Addr: DefaultSensorAddress, W: []uint8{0xe0, 0x0}, R: []uint8{0x70, 0xe0, 0x7b, 0x3f, 0xf7, 0xbf}},
+	{Addr: DefaultSensorAddress, W: []uint8{0x36, 0x83}, R: []uint8{0xc2, 0x95, 0x3e}},
+	{Addr: DefaultSensorAddress, W: []uint8{0x36, 0x84}, R: []uint8{0xb1, 0x49, 0x51}},
+	{Addr: DefaultSensorAddress, W: []uint8{0x36, 0x85}, R: []uint8{0x15, 0x21, 0x2f}},
+	{Addr: DefaultSensorAddress, W: []uint8{0xa0, 0x4}, R: []uint8{0x19, 0xba, 0x48}},
+	{Addr: DefaultSensorAddress, W: []uint8{0x37, 0x81}, R: []uint8{0x30, 0x0, 0x33}},
+	{Addr: DefaultSensorAddress, W: []uint8{0xf3, 0x2d}, R: []uint8{0x80, 0x10, 0xe1}},
+	{Addr: DefaultSensorAddress, W: []uint8{0x30, 0x41}},
+	{Addr: DefaultSensorAddress, W: []uint8{0xe1, 0x2}, R: []uint8{0x34, 0x66, 0xad}},
+	{Addr: DefaultSensorAddress, W: []uint8{0xe1, 0x1f}, R: []uint8{0xcd, 0x33, 0xfd}},
+	{Addr: DefaultSensorAddress, W: []uint8{0xe1, 0x9}, R: []uint8{0x38, 0x69, 0x37}},
+	{Addr: DefaultSensorAddress, W: []uint8{0xe1, 0x14}, R: []uint8{0xc9, 0x2d, 0x22}},
+	{Addr: DefaultSensorAddress, W: []uint8{0x30, 0x93}},
+	{Addr: DefaultSensorAddress, W: []uint8{0x36, 0x83}, R: []uint8{0xc2, 0x95, 0x3e}},
+	{Addr: DefaultSensorAddress, W: []uint8{0x36, 0x84}, R: []uint8{0xb1, 0x49, 0x51}},
+	{Addr: DefaultSensorAddress, W: []uint8{0x36, 0x85}, R: []uint8{0x15, 0x21, 0x2f}},
+	{Addr: DefaultSensorAddress, W: []uint8{0xa0, 0x4}, R: []uint8{0x19, 0xba, 0x48}},
+	{Addr: DefaultSensorAddress, W: []uint8{0x37, 0x81}, R: []uint8{0x30, 0x0, 0x33}},
+	{Addr: DefaultSensorAddress, W: []uint8{0xf3, 0x2d}, R: []uint8{0x0, 0x0, 0x81}},
+	{Addr: DefaultSensorAddress, W: []uint8{0x30, 0x41}},
+	{Addr: DefaultSensorAddress, W: []uint8{0xe1, 0x2}, R: []uint8{0x34, 0x66, 0xad}},
+	{Addr: DefaultSensorAddress, W: []uint8{0xe1, 0x1f}, R: []uint8{0xcd, 0x33, 0xfd}},
+	{Addr: DefaultSensorAddress, W: []uint8{0xe1, 0x9}, R: []uint8{0x38, 0x69, 0x37}},
+	{Addr: DefaultSensorAddress, W: []uint8{0xe1, 0x14}, R: []uint8{0xc9, 0x2d, 0x22}},
+	{Addr: DefaultSensorAddress, W: []uint8{0xa0, 0x4, 0x80, 0x80, 0xd8}},
+	{Addr: DefaultSensorAddress, W: []uint8{0x61, 0x0, 0x4c, 0x1d, 0xb3}},
+	{Addr: DefaultSensorAddress, W: []uint8{0x61, 0x1d, 0xbe, 0xdb, 0x93}},
+	{Addr: DefaultSensorAddress, W: []uint8{0x61, 0xb, 0x58, 0x2b, 0x3d}},
+	{Addr: DefaultSensorAddress, W: []uint8{0x61, 0x16, 0xb2, 0xcc, 0xf3}},
+	{Addr: DefaultSensorAddress, W: []uint8{0x36, 0x83}, R: []uint8{0xc2, 0x95, 0x3e}},
+	{Addr: DefaultSensorAddress, W: []uint8{0x36, 0x84}, R: []uint8{0xb1, 0x49, 0x51}},
+	{Addr: DefaultSensorAddress, W: []uint8{0x36, 0x85}, R: []uint8{0x15, 0x21, 0x2f}},
+	{Addr: DefaultSensorAddress, W: []uint8{0xa0, 0x4}, R: []uint8{0x80, 0x80, 0xd8}},
+	{Addr: DefaultSensorAddress, W: []uint8{0x37, 0x81}, R: []uint8{0x30, 0x0, 0x33}},
+	{Addr: DefaultSensorAddress, W: []uint8{0xf3, 0x2d}, R: []uint8{0x0, 0x0, 0x81}},
+	{Addr: DefaultSensorAddress, W: []uint8{0x30, 0x41}},
+	{Addr: DefaultSensorAddress, W: []uint8{0xe1, 0x2}, R: []uint8{0x4c, 0x1d, 0xb3}},
+	{Addr: DefaultSensorAddress, W: []uint8{0xe1, 0x1f}, R: []uint8{0xbe, 0xdb, 0x93}},
+	{Addr: DefaultSensorAddress, W: []uint8{0xe1, 0x9}, R: []uint8{0x58, 0x2b, 0x3d}},
+	{Addr: DefaultSensorAddress, W: []uint8{0xe1, 0x14}, R: []uint8{0xb2, 0xcc, 0xf3}},
+	{Addr: DefaultSensorAddress, W: []uint8{0x23, 0x34}},
+	{Addr: DefaultSensorAddress, W: []uint8{0xe0, 0x0}, R: []uint8{0x62, 0x77, 0x62, 0x4a, 0x94, 0x1b}},
+	{Addr: DefaultSensorAddress, W: []uint8{0xf3, 0x2d}, R: []uint8{0x89, 0x0, 0x61}},
+	{Addr: DefaultSensorAddress, W: []uint8{0x30, 0x41}},
+	{Addr: DefaultSensorAddress, W: []uint8{0x30, 0x93}},
+	{Addr: DefaultSensorAddress, W: []uint8{0x30, 0xa2}}}
+
+func init() {
+	var err error
+
+	liveDevice = os.Getenv("HDC302X") != ""
+
+	// Make sure periph is initialized.
+	if _, err = host.Init(); err != nil {
+		fmt.Println(err)
+	}
+
+	if liveDevice {
+		bus, err = i2creg.Open("")
+		if err != nil {
+			fmt.Println(err)
+		}
+		// Add the recorder to dump the data stream when we're using a live device.
+		bus = &i2ctest.Record{Bus: bus}
+	} else {
+		bus = &i2ctest.Playback{DontPanic: true}
+	}
+}
+
+// getDev returns a configured device using either an i2c bus, or a playback bus.
+func getDev(t *testing.T, playbackOps ...[]i2ctest.IO) (*Dev, error) {
+	if liveDevice {
+		if recorder, ok := bus.(*i2ctest.Record); ok {
+			// Clear the operations buffer.
+			recorder.Ops = make([]i2ctest.IO, 0, 32)
+		}
+
+	} else {
+		if len(playbackOps) == 1 {
+			pb := bus.(*i2ctest.Playback)
+			pb.Ops = playbackOps[0]
+			pb.Count = 0
+		}
+	}
+	dev, err := NewI2C(bus, DefaultSensorAddress, RateFourHertz)
+
+	if err != nil {
+		t.Log("error constructing dev")
+		t.Fatal(err)
+	}
+
+	return dev, err
+}
+
+// shutdown dumps the recorder values if we we're running a live device.
+func shutdown(t *testing.T) {
+	if recorder, ok := bus.(*i2ctest.Record); ok {
+		t.Logf("%#v", recorder.Ops)
+	}
+}
+
+func TestCRC(t *testing.T) {
+	var tests = []struct {
+		bytes  []byte
+		result byte
+	}{
+		{bytes: []byte{0xbe, 0xef}, result: 0x92},
+		{bytes: []byte{0xab, 0xcd}, result: 0x6f},
+	}
+	for _, test := range tests {
+		res := crc8(test.bytes)
+		if res != test.result {
+			t.Errorf("crc8(%#v)!=0x%d receieved 0x%d", test.bytes, test.result, res)
+		}
+	}
+}
+
+// TestConversions tests the various temperature/humidity functions
+// for correct operation.
+func TestConversions(t *testing.T) {
+	envPrecision := physic.Env{}
+	dev := Dev{}
+	dev.Precision(&envPrecision)
+	t.Logf("Precision: Temperature: %d nanoKelvin Humidity: %d TenthMicroPercent RH", envPrecision.Temperature, envPrecision.Humidity)
+
+	temp := countToTemperature([]byte{0x00, 0x00})
+	expected := physic.ZeroCelsius - 45*physic.Celsius
+	if temp != expected {
+		t.Errorf("unexpected countToTemperature. expected %s, received %s %d", expected, temp, temp)
+	}
+	temp = countToTemperature([]byte{0xd4, 0x1c})
+	expected = physic.ZeroCelsius + 100*physic.Celsius
+	if math.Abs(float64(expected-temp)) > float64(envPrecision.Temperature) {
+		t.Errorf("unexpected countToTemperature. expected %s (%d), received %s (%d)", expected, expected, temp, temp)
+	}
+
+	var hTests = []struct {
+		bytes  []byte
+		result physic.RelativeHumidity
+	}{
+		{bytes: []byte{0x0, 0x0}, result: physic.RelativeHumidity(0)},
+		{bytes: []byte{0x80, 0x0}, result: 50 * physic.PercentRH},
+		{bytes: []byte{0xff, 0xff}, result: 100 * physic.PercentRH},
+	}
+	for _, hTest := range hTests {
+		humidity := countToHumidity(hTest.bytes)
+		if (humidity - hTest.result) > envPrecision.Humidity {
+			t.Errorf("unexpected humidity got %s (%d) expected %s (%d)", humidity, humidity, hTest.result, hTest.result)
+		}
+	}
+
+}
+
+// Tests the conversions of offsets to binary offset values used by the device.
+func TestOffsetConversions(t *testing.T) {
+	// These are a subtly off from the datasheet because it's using floating point representation,
+	var tempOffsets = []struct {
+		temperature    physic.Temperature
+		expectedResult byte
+	}{
+		{temperature: 170_902 * physic.MicroKelvin, expectedResult: 0x81},
+		{temperature: -170_902 * physic.MicroKelvin, expectedResult: 0x01}, // Test sign handling
+		{temperature: 7_178_000 * physic.MicroKelvin, expectedResult: 0xaa},
+		{temperature: 10_937_700 * physic.MicroKelvin, expectedResult: 0xc0},
+		{temperature: 21_704_500 * physic.MicroKelvin, expectedResult: 0xff},
+	}
+	for _, test := range tempOffsets {
+		res := computeTemperatureOffsetByte(test.temperature)
+		if res != test.expectedResult {
+			t.Errorf("computeTemperatureOffsetByte() Offset: %s Expected Value: 0x%x Received: 0x%x", test.temperature, test.expectedResult, res)
+		}
+	}
+
+	// Now repeat for humidity
+	var humidityOffsets = []struct {
+		humidity       physic.RelativeHumidity
+		expectedResult byte
+	}{
+		{humidity: 19532 * physic.TenthMicroRH, expectedResult: 0x81},
+		{humidity: -19532 * physic.TenthMicroRH, expectedResult: 0x01},
+		{humidity: 820326 * physic.TenthMicroRH, expectedResult: 0xaa},
+		{humidity: -24_805_1 * physic.MicroRH, expectedResult: 0x7f},
+	}
+	for _, test := range humidityOffsets {
+		res := computeHumidityOffsetByte(test.humidity)
+		if res != test.expectedResult {
+			t.Errorf("computeHumidityOffsetByte() Offset: %s Expected Value: 0x%x Received: 0x%x", test.humidity, test.expectedResult, res)
+		}
+	}
+
+}
+
+func TestBasic(t *testing.T) {
+	dev, err := getDev(t, []i2ctest.IO{pbSense[0]})
+	if err != nil {
+		t.Fatal(err)
+	}
+	env := &physic.Env{}
+	dev.Precision(env)
+	if env.Pressure != 0 {
+		t.Error("this device doesn't measure pressure")
+	}
+	if env.Temperature != (2670329 * physic.NanoKelvin) {
+		t.Errorf("incorrect temperature precision value got %d expected %d", env.Temperature, 2670329*physic.NanoKelvin)
+	}
+	if env.Humidity != 153*physic.TenthMicroRH {
+		t.Errorf("incorrect humidity precision got %d expected %d", env.Humidity, 153*physic.TenthMicroRH)
+	}
+
+	s := dev.String()
+	if len(s) == 0 {
+		t.Error("invalid value for String()")
+	}
+}
+
+func TestSense(t *testing.T) {
+	d, err := getDev(t, pbSense)
+
+	if err != nil {
+		t.Fatalf("failed to initialize hdc302x: %v", err)
+	}
+	defer shutdown(t)
+
+	// Read temperature and humidity from the sensor
+	e := physic.Env{}
+	if err := d.Sense(&e); err != nil {
+		t.Error(err)
+	}
+	t.Logf("%8s %9s", e.Temperature, e.Humidity)
+
+	if !liveDevice {
+		// The playback temp is 26.621C Ensure that's what we got.
+		expected := physic.Temperature(299770889600)
+		if e.Temperature != expected {
+			t.Errorf("incorrect temperature value read. Expected: %s (%d) Found: %s (%d)",
+				expected.String(),
+				expected,
+				e.Temperature.String(),
+				e.Temperature,
+			)
+		}
+
+		// 23.2% expected.
+		expectedRH := 2324559 * physic.TenthMicroRH
+		if e.Humidity != expectedRH {
+			t.Errorf("incorrect humidity value read. Expected: %s (%d) Found: %s (%d)",
+				expectedRH.String(),
+				expectedRH,
+				e.Humidity.String(),
+				e.Humidity,
+			)
+		}
+	}
+
+}
+
+func TestSenseContinuous(t *testing.T) {
+
+	readCount := int32(10)
+
+	// make 10 copies of the single reading playback data.
+	pb := make([]i2ctest.IO, 0, readCount+1)
+	pb = append(pb, pbSense[0])
+	for range readCount {
+		pb = append(pb, pbSense[1])
+	}
+	// Add in the halt
+	pb = append(pb, i2ctest.IO{Addr: DefaultSensorAddress,
+		W: []uint8{stopContinuousReadings[0], stopContinuousReadings[1]}})
+
+	dev, err := getDev(t, pb)
+	if err != nil {
+		t.Error(fmt.Errorf("failed to initialize hd302x: %w", err))
+	}
+	defer shutdown(t)
+
+	_, err = dev.SenseContinuous(100 * time.Millisecond)
+	if err == nil {
+		t.Error("expected error for sense continuous interval < sample interval")
+	}
+
+	ch, err := dev.SenseContinuous(time.Second)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	_, err = dev.SenseContinuous(time.Second)
+	if err == nil {
+		t.Error("expected an error for attempting concurrent SenseContinuous")
+	}
+
+	counter := atomic.Int32{}
+	tEnd := time.Now().UnixMilli() + int64(readCount+2)*1000
+	wg := sync.WaitGroup{}
+	wg.Add(1)
+	go func() {
+		for {
+			time.Sleep(100 * time.Millisecond)
+			// Stay here until we get the expected number of reads, or the time
+			// has expired.
+			if counter.Load() == readCount || time.Now().UnixMilli() > tEnd {
+				err := dev.Halt()
+				if err != nil {
+					t.Error(err)
+				}
+				wg.Done()
+				return
+			}
+		}
+	}()
+
+	for e := range ch {
+		counter.Add(1)
+		t.Log(time.Now(), e)
+	}
+	if counter.Load() != readCount {
+		t.Errorf("expected %d readings. received %d", readCount, counter.Load())
+	}
+	wg.Wait()
+}
+
+func TestConfiguration(t *testing.T) {
+	dev, err := getDev(t, pbConfiguration)
+	if err != nil {
+		t.Fatalf("failed to initialize hd302x: %v", err)
+	}
+	defer shutdown(t)
+
+	cfg, err := dev.Configuration()
+	if err != nil {
+		t.Error(err)
+	}
+	s := cfg.String()
+	t.Log("configuration: ", s)
+	if len(s) == 0 {
+		t.Errorf("invalid Configuration.String()")
+	}
+	if cfg.SerialNumber == 0 {
+		t.Error("invalid serial number")
+	}
+	if cfg.VendorID != 0x3000 {
+		t.Errorf("invalid manufacturer id 0x%x", cfg.VendorID)
+	}
+}
+
+// Tests applying offsets for temperature and humidity and checking that
+// the values are applied during a subsequent read.
+func TestOffsetModification(t *testing.T) {
+	dev, err := getDev(t, pbOffsets)
+	if err != nil {
+		t.Fatalf("failed to initialize hd302x: %v", err)
+	}
+	defer shutdown(t)
+	env := physic.Env{}
+	err = dev.Sense(&env)
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Logf("Initial Readings: %s", env)
+	cfg, err := dev.Configuration()
+	if err != nil {
+		t.Fatal(err)
+	}
+	cfg.TemperatureOffset += 10 * physic.Celsius
+	cfg.HumidityOffset -= 5 * physic.PercentRH
+	t.Log("writing configuration: ", cfg)
+	err = dev.SetConfiguration(cfg)
+
+	if err != nil {
+		t.Fatal(err)
+	}
+	cfg2, _ := dev.Configuration()
+	t.Logf("read configuration=%s", cfg2)
+	env2 := physic.Env{}
+	err = dev.Sense(&env2)
+	if err != nil {
+		t.Error(err)
+	}
+	t.Log("Second Readings (post offset): ", env2)
+	if env2.Temperature < (env.Temperature+(9_500*physic.MilliKelvin)) ||
+		env2.Temperature > (env.Temperature+(10_500*physic.MilliKelvin)) {
+		t.Errorf("offset temperature invalid. Expected ~ %s + 10C Got: %s", env.Temperature, env2.Temperature)
+	}
+
+	lLow := env.Humidity - 6*physic.PercentRH
+	lHigh := env.Humidity - 4*physic.PercentRH
+	if (env2.Humidity < lLow) ||
+		(env2.Humidity > lHigh) {
+		t.Errorf("offset humidity invalid. Expected ~ %s - 5%% Got: %s Lower Limit: %s, Upper Limit: %s", env.Humidity, env2.Humidity, lLow, lHigh)
+	}
+
+	// Issue a soft reset to make sure any alterations are undone.
+	_ = dev.Reset()
+}
+
+// Tests using alert values.
+func TestAlerts(t *testing.T) {
+
+	dev, err := getDev(t, pbAlerts)
+	if err != nil {
+		t.Fatalf("failed to initialize hd302x: %v", err)
+	}
+	defer shutdown(t)
+	env := physic.Env{}
+	err = dev.Sense(&env)
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Logf("Initial Temperature/Humidity Readings: %s", env)
+	cfg, err := dev.Configuration()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	cfg.TemperatureOffset = 0
+	cfg.HumidityOffset = 0
+	cfg.AlertThresholds.Low.Temperature = 10 * physic.Celsius
+	cfg.AlertThresholds.High.Temperature = 75 * physic.Celsius
+	// Purposely set the low limit so it will trigger an alert on the status bit.
+	cfg.AlertThresholds.Low.Humidity = env.Humidity + 5*physic.PercentRH
+	cfg.AlertThresholds.High.Humidity = 75 * physic.PercentRH
+
+	cfg.ClearThresholds.Low.Temperature = 15 * physic.Celsius
+	cfg.ClearThresholds.High.Temperature = 70 * physic.Celsius
+	cfg.ClearThresholds.Low.Humidity = cfg.AlertThresholds.Low.Humidity + 5*physic.PercentRH
+	cfg.ClearThresholds.High.Humidity = 70 * physic.PercentRH
+	t.Logf("Writing Configuration:\n%s", cfg)
+	// write the Alert levels
+	err = dev.SetConfiguration(cfg)
+	if err != nil {
+		t.Fatal(err)
+	}
+	// Re-read the configuration.
+	cfg2, err := dev.Configuration()
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Logf("re-read configuration = \n%s", cfg2)
+	// Trigger a read and then get the status word. We should have a humidity alert set...
+	_ = dev.Sense(&env)
+	status, err := dev.ReadStatus()
+	if err != nil {
+		t.Error(err)
+	}
+	_ = dev.Halt()
+
+	// Verify things are within one lsb
+	if !cfg.AlertThresholds.Low.ApproximatelyEquals(&cfg2.AlertThresholds.Low) {
+		t.Errorf("error in low alert thresholds set: %s read: %s", cfg.AlertThresholds.Low.String(), cfg2.AlertThresholds.Low.String())
+	}
+	if !cfg.AlertThresholds.High.ApproximatelyEquals(&cfg2.AlertThresholds.High) {
+		t.Errorf("error in high alert thresholds set: %s read: %s", cfg.AlertThresholds.High.String(), cfg2.AlertThresholds.High.String())
+	}
+	if !cfg.ClearThresholds.Low.ApproximatelyEquals(&cfg2.ClearThresholds.Low) {
+		t.Errorf("error in low clear thresholds set: %s read: %s", cfg.ClearThresholds.Low.String(), cfg2.ClearThresholds.Low.String())
+	}
+	if !cfg.ClearThresholds.High.ApproximatelyEquals(&cfg2.ClearThresholds.High) {
+		t.Errorf("error in high clear thresholds set: %s read: %s", cfg.ClearThresholds.High.String(), cfg2.ClearThresholds.High.String())
+	}
+
+	if status&StatusActiveAlerts != StatusActiveAlerts {
+		t.Error("expected status active alerts to be set")
+	}
+	if status&StatusRHTrackingAlert != StatusRHTrackingAlert {
+		t.Error("expected rh tracking alerts to be set")
+	}
+	if status&StatusRHLowTrackingAlert != StatusRHLowTrackingAlert {
+		t.Error("expected RH Low Tracking alert status bit to be set")
+	}
+
+	// Issue a soft reset to make sure any alterations are undone.
+	_ = dev.Reset()
+}
+
+// TestHeater turns on the sensor's integrated heater. The heater
+// can be used to remove condensation from the sensor.
+func TestHeater(t *testing.T) {
+	dev, err := getDev(t, pbHeater)
+	if err != nil {
+		t.Fatalf("failed to initialize hd302x: %v", err)
+	}
+	defer shutdown(t)
+
+	err = dev.SetHeater(PowerFull + 1)
+	if err == nil {
+		t.Error("expected error with invalid power value")
+	}
+	env := physic.Env{}
+	env2 := physic.Env{}
+	err = dev.Sense(&env)
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Logf("initial temperature: %s Humidity: %s", env.Temperature, env.Humidity)
+	err = dev.SetHeater(PowerFull)
+	defer func() {
+		if errOff := dev.SetHeater(PowerOff); errOff != nil {
+			t.Error(errOff)
+		}
+	}()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if liveDevice {
+		for range 5 {
+			t.Log("Sleeping 5 seconds to test heater...")
+			time.Sleep(time.Second)
+		}
+	}
+	err = dev.Sense(&env2)
+
+	if err != nil {
+		t.Error(err)
+	}
+	t.Logf("final temperature after heater enabled: %s Humidity: %s", env2.Temperature, env2.Humidity)
+	if env2.Temperature <= env.Temperature {
+		t.Errorf("expected heater to increase sensor temperature. Initial: %s Final: %s", env.Temperature, env2.Temperature)
+	}
+}

scd4x/scd4x_test.go

@@ -12,6 +12,8 @@ package scd4x
 import (
 	"fmt"
 	"os"
+	"sync"
+	"sync/atomic"
 	"testing"
 	"time"
 
@@ -235,7 +237,7 @@ func TestSense(t *testing.T) {
 }
 
 func TestSenseContinuous(t *testing.T) {
-	readings := 6
+	readings := int32(6)
 	timeBase := time.Second
 	if liveDevice {
 		timeBase *= 10
@@ -244,26 +246,36 @@ func TestSenseContinuous(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	defer func() { _ = dev.Halt() }()
+
 	defer shutdown(t)
 	t.Log("dev.sensing=", dev.sensing)
 	ch, err := dev.SenseContinuous(timeBase)
 	if err != nil {
 		t.Error(err)
 	}
-
+	received := atomic.Int32{}
+	wg := sync.WaitGroup{}
+	wg.Add(1)
+	tEnd := time.Now().UnixMilli() + int64(readings+2)*1000
 	go func() {
-		time.Sleep(time.Duration(readings) * timeBase)
+		for {
-		_ = dev.Halt()
+			if received.Load() == readings || time.Now().UnixMilli() > tEnd {
+				_ = dev.Halt()
+				wg.Done()
+				break
+			}
+		}
 	}()
-	received := 0
+
 	for env := range ch {
+		received.Add(1)
 		t.Log(env.String())
-		received += 1
+
 	}
-	if received < (readings-1) || received > readings {
+	if received.Load() != readings {
-		t.Errorf("SenseContinuous() expected at least %d readings, got %d", readings-1, received)
+		t.Errorf("SenseContinuous() expected at least %d readings, got %d", readings-1, received.Load())
 	}
+	wg.Wait()
 
 }
 
@@ -335,7 +347,7 @@ func TestGetSetConfiguration(t *testing.T) {
 // previously programmed into the device.
 func TestPersistAndResetFactory(t *testing.T) {
 	if !liveDevice || os.Getenv("SCDRESET") == "" {
-		t.Skip("using live device and SCDRESET not defined. skipping")
+		t.Skip("not using live device or SCDRESET not defined. skipping")
 	}
 	dev, err := getDev(t)
 	if err != nil {