onewire(ds18b20): introduce 1-wire device access by sysfs and temp dr…

…iver

adaptor.go

@@ -176,6 +176,18 @@ type SpiSystemDevicer interface {
 	Close() error
 }
 
+// OneWireSystemDevicer is the interface to a 1-wire device at system level.
+type OneWireSystemDevicer interface {
+	// ReadData reads byte data from the device
+	ReadData(command string, data []byte) error
+	// WriteData writes byte data to the device
+	WriteData(command string, data []byte) error
+	// ReadInteger reads an integer value from the device
+	ReadInteger(command string) (int, error)
+	// Close the 1-wire connection.
+	Close() error
+}
+
 // BusOperations are functions provided by a bus device, e.g. SPI, i2c.
 type BusOperations interface {
 	// ReadByteData reads a byte from the given register of bus device.
@@ -213,6 +225,18 @@ type SpiOperations interface {
 	Close() error
 }
 
+// OneWireOperations are the wrappers around the actual functions used by the 1-wire device interface
+type OneWireOperations interface {
+	// ReadData reads from the device
+	ReadData(command string, data []byte) error
+	// WriteData writes to the device
+	WriteData(command string, data []byte) error
+	// ReadInteger reads an integer value from the device
+	ReadInteger(command string) (int, error)
+	// Close the connection.
+	Close() error
+}
+
 // Adaptor is the interface that describes an adaptor in gobot
 type Adaptor interface {
 	// Name returns the label for the Adaptor

drivers/onewire/ds18b20_driver.go

@@ -0,0 +1,133 @@
+package onewire
+
+import (
+	"fmt"
+)
+
+// ds18b20OptionApplier needs to be implemented by each configurable option type
+type ds18b20OptionApplier interface {
+	apply(cfg *ds18b20Configuration)
+}
+
+// ds18b20Configuration contains all changeable attributes of the driver.
+type ds18b20Configuration struct {
+	scaleUnit  func(int) float32
+	resolution uint8
+}
+
+// ds18b20UnitscalerOption is the type for applying another unit scaler to the configuration
+type ds18b20UnitscalerOption struct {
+	unitscaler func(int) float32
+}
+
+type ds18b20ResolutionOption uint8
+
+// DS18B20Driver is a driver for the DS18B20 1-wire temperature sensor.
+type DS18B20Driver struct {
+	*driver
+	ds18b20Cfg *ds18b20Configuration
+}
+
+// NewDS18B20Driver creates a new Gobot Driver for DS18B20 RGB LEDs.
+//
+// Params:
+//
+//	a *Adaptor - the Adaptor to use with this Driver.
+//	count int - how many LEDs are in the array controlled by this driver.
+//	bright - the default brightness to apply for all LEDs (must be between 0 and 31).
+//
+// Optional params:
+//
+//	onewire.WithBusNumber(int):  bus to use with this driver, instead of the default bus 1.
+func NewDS18B20Driver(a Connector, serialNumber uint64, opts ...interface{}) *DS18B20Driver {
+	d := &DS18B20Driver{
+		driver: newDriver(a, "DS18B20", 0x28, serialNumber),
+		ds18b20Cfg: &ds18b20Configuration{
+			scaleUnit: func(input int) float32 { return float32(input) / 1000 }, // 1000:1 in °C
+		},
+	}
+	for _, opt := range opts {
+		switch o := opt.(type) {
+		case optionApplier:
+			o.apply(d.driverCfg)
+		case ds18b20OptionApplier:
+			o.apply(d.ds18b20Cfg)
+		default:
+			panic(fmt.Sprintf("'%s' can not be applied on '%s'", opt, d.driverCfg.name))
+		}
+	}
+	return d
+}
+
+// WithFahrenheit substitute the default °C scaler by a scaler for °F
+func WithFahrenheit() ds18b20OptionApplier {
+	// (1°C × 9/5) + 32 = 33,8°F
+	unitscaler := func(input int) float32 { return float32(input)/1000*9.0/5.0 + 32.0 }
+	return ds18b20UnitscalerOption{unitscaler: unitscaler}
+}
+
+// WithResolution substitute the default 12 bit resolution by the given one (9, 10, 11)
+// Please also note, that each smaller resolution will decrease the conversion time by a factor of 2
+func WithResolution(resolution byte) ds18b20OptionApplier {
+	return ds18b20ResolutionOption(resolution)
+}
+
+// Temperature returns the current temperature, in celsius degrees, if the default unit scaler is used.
+func (d *DS18B20Driver) Temperature() (float32, error) {
+	d.mutex.Lock()
+	defer d.mutex.Unlock()
+
+	val, err := d.connection.ReadInteger("temperature")
+	if err != nil {
+		return 0, err
+	}
+
+	return d.ds18b20Cfg.scaleUnit(val), nil
+}
+
+// Resolution returns the current resolution in bits (9, 10, 11, 12)
+func (d *DS18B20Driver) Resolution() (uint8, error) {
+	d.mutex.Lock()
+	defer d.mutex.Unlock()
+
+	val, err := d.connection.ReadInteger("resolution")
+	if err != nil {
+		return 0, err
+	}
+
+	return uint8(val), nil
+}
+
+// IsExternalPowered returns whether the device is external or parasitic powered
+func (d *DS18B20Driver) IsExternalPowered() (bool, error) {
+	d.mutex.Lock()
+	defer d.mutex.Unlock()
+
+	val, err := d.connection.ReadInteger("ext_power")
+	if err != nil {
+		return false, err
+	}
+
+	return val > 0, nil
+}
+
+// ConversionTime returns the conversion time in ms (93, 187, 375, 750)
+func (d *DS18B20Driver) ConversionTime() (uint16, error) {
+	d.mutex.Lock()
+	defer d.mutex.Unlock()
+
+	val, err := d.connection.ReadInteger("conv_time")
+	if err != nil {
+		return 0, err
+	}
+
+	return uint16(val), nil
+}
+
+func (o ds18b20UnitscalerOption) apply(cfg *ds18b20Configuration) {
+	cfg.scaleUnit = o.unitscaler
+}
+
+func (o ds18b20ResolutionOption) apply(cfg *ds18b20Configuration) {
+	cfg.resolution = uint8(o)
+}

drivers/onewire/onewire_connection.go

@@ -0,0 +1,51 @@
+package onewire
+
+import (
+	"sync"
+
+	"gobot.io/x/gobot/v2"
+)
+
+// onewireConnection is the common implementation of the 1-wire bus interface.
+type onewireConnection struct {
+	onewireSystem gobot.OneWireSystemDevicer
+	mutex         sync.Mutex
+}
+
+// NewConnection uses the given 1-wire system device and provides it as gobot.OneWireOperations
+// and Implements gobot.BusOperations.
+func NewConnection(onewireSystem gobot.OneWireSystemDevicer) *onewireConnection {
+	return &onewireConnection{onewireSystem: onewireSystem}
+}
+
+// Close connection to underlying SPI device. Implements functions of onewire.Connection respectively
+// gobot.OneWireOperations.
+func (c *onewireConnection) Close() error {
+	c.mutex.Lock()
+	defer c.mutex.Unlock()
+
+	return c.onewireSystem.Close()
+}
+
+// ReadData reads the data according the command, e.g. from the specified file on sysfs bus.
+func (c *onewireConnection) ReadData(command string, data []byte) error {
+	c.mutex.Lock()
+	defer c.mutex.Unlock()
+
+	return c.onewireSystem.ReadData(command, data)
+}
+
+// WriteData writes the data according the command, e.g. to the specified file on sysfs bus.
+func (c *onewireConnection) WriteData(command string, data []byte) error {
+	c.mutex.Lock()
+	defer c.mutex.Unlock()
+
+	return c.onewireSystem.WriteData(command, data)
+}
+
+func (c *onewireConnection) ReadInteger(command string) (int, error) {
+	c.mutex.Lock()
+	defer c.mutex.Unlock()
+
+	return c.onewireSystem.ReadInteger(command)
+}

drivers/onewire/onewire_driver.go

@@ -0,0 +1,131 @@
+package onewire
+
+import (
+	"fmt"
+	"log"
+	"sync"
+
+	"gobot.io/x/gobot/v2"
+)
+
+// Connector lets adaptors provide the drivers to get access to the 1-wire devices on platforms.
+type Connector interface {
+	// GetOneWireConnection returns a connection to a 1-wire device with family code and serial number.
+	GetOneWireConnection(familyCode byte, serialNumber uint64) (Connection, error)
+}
+
+// Connection is a connection to a 1-wire device with family code and serial number on a specific bus, provided by
+// an adaptor, usually just by calling the onewire package's GetOneWireConnection() function.
+type Connection gobot.OneWireOperations
+
+// optionApplier needs to be implemented by each configurable option type
+type optionApplier interface {
+	apply(cfg *configuration)
+}
+
+// configuration contains all changeable attributes of the driver.
+type configuration struct {
+	name         string
+	familyCode   byte
+	serialNumber uint64
+}
+
+// nameOption is the type for applying another name to the configuration
+type nameOption string
+
+// Driver implements the interface gobot.Driver.
+type driver struct {
+	driverCfg  *configuration
+	connector  Connector
+	connection Connection
+	afterStart func() error
+	beforeHalt func() error
+	gobot.Commander
+	mutex *sync.Mutex // mutex often needed to ensure that write-read sequences are not interrupted
+}
+
+// newDriver creates a new generic and basic 1-wire gobot driver.
+//
+// Supported options:
+//
+//	"WithName"
+func newDriver(a Connector, name string, familyCode byte, serialNumber uint64, opts ...interface{}) *driver {
+	d := &driver{
+		driverCfg:  &configuration{name: gobot.DefaultName(name), familyCode: familyCode, serialNumber: serialNumber},
+		connector:  a,
+		afterStart: func() error { return nil },
+		beforeHalt: func() error { return nil },
+		Commander:  gobot.NewCommander(),
+		mutex:      &sync.Mutex{},
+	}
+
+	for _, opt := range opts {
+		switch o := opt.(type) {
+		case optionApplier:
+			o.apply(d.driverCfg)
+		default:
+			panic(fmt.Sprintf("'%s' can not be applied on '%s'", opt, d.driverCfg.name))
+		}
+	}
+
+	return d
+}
+
+// WithName is used to replace the default name of the driver.
+func WithName(name string) optionApplier {
+	return nameOption(name)
+}
+
+// Name returns the name of the device.
+func (d *driver) Name() string {
+	return d.driverCfg.name
+}
+
+// SetName sets the name of the device.
+func (d *driver) SetName(name string) {
+	d.driverCfg.name = name
+}
+
+// Connection returns the connection of the device.
+func (d *driver) Connection() gobot.Connection {
+	if conn, ok := d.connection.(gobot.Connection); ok {
+		return conn
+	}
+
+	log.Printf("%s has no gobot connection\n", d.driverCfg.name)
+	return nil
+}
+
+// Start initializes the device.
+func (d *driver) Start() error {
+	d.mutex.Lock()
+	defer d.mutex.Unlock()
+
+	var err error
+	d.connection, err = d.connector.GetOneWireConnection(d.driverCfg.familyCode, d.driverCfg.serialNumber)
+	if err != nil {
+		return err
+	}
+
+	return d.afterStart()
+}
+
+// Halt halts the device.
+func (d *driver) Halt() error {
+	d.mutex.Lock()
+	defer d.mutex.Unlock()
+
+	// currently there is nothing to do here for the driver, the connection is cached on adaptor side
+	// and will be closed on adaptor Finalize()
+
+	return d.beforeHalt()
+}
+
+func (o nameOption) String() string {
+	return "name option for 1-wire drivers"
+}
+
+// apply change the name in the configuration.
+func (o nameOption) apply(c *configuration) {
+	c.name = string(o)
+}