release: update versions to 0.7.0

Signed-off-by: Ron Evans <ron@hybridgroup.com>

CHANGELOG.md

@@ -1,3 +1,23 @@
+0.7.0
+---
+- **new devices**
+    - veml6070: add Vishay UV light sensor
+- **enhancements**
+    - lis3dh: example uses I2C1 so requires config to specify pins since they are not default
+    - ssd1331: make SPI TX faster
+    - st7735: make SPI Tx faster
+- **docs**
+    - complete missing GoDocs for main and sub-packages
+- **core**
+    - add Version string for support purposes
+- **examples**
+    - Change all espat driver examples to use Arduino Nano33 IoT by default
+
+0.6.0
+---
+- **new devices**
+    - Support software SPI for APA102 (Itsy Bitsy M0 on-board "Dotstar" LED as example)
+
 0.5.0
 ---
 - **new devices**

Makefile

@@ -11,6 +11,7 @@ smoke-test:
 	@mkdir -p build
 	tinygo build -size short -o ./build/test.elf -target=itsybitsy-m0 ./examples/adxl345/main.go
 	tinygo build -size short -o ./build/test.elf -target=itsybitsy-m0 ./examples/apa102/main.go
+	tinygo build -size short -o ./build/test.elf -target=itsybitsy-m0 ./examples/apa102/itsybitsy-m0/main.go
 	tinygo build -size short -o ./build/test.elf -target=microbit ./examples/at24cx/main.go
 	tinygo build -size short -o ./build/test.elf -target=itsybitsy-m0 ./examples/bh1750/main.go
 	tinygo build -size short -o ./build/test.elf -target=itsybitsy-m0 ./examples/blinkm/main.go
@@ -19,9 +20,9 @@ smoke-test:
 	tinygo build -size short -o ./build/test.elf -target=bluepill ./examples/ds1307/time/main.go
 	tinygo build -size short -o ./build/test.elf -target=itsybitsy-m0 ./examples/ds3231/main.go
 	tinygo build -size short -o ./build/test.elf -target=microbit ./examples/easystepper/main.go
-	tinygo build -size short -o ./build/test.elf -target=itsybitsy-m0 ./examples/espat/espconsole/main.go
-	tinygo build -size short -o ./build/test.elf -target=itsybitsy-m0 ./examples/espat/esphub/main.go
-	tinygo build -size short -o ./build/test.elf -target=itsybitsy-m0 ./examples/espat/espstation/main.go
+	tinygo build -size short -o ./build/test.elf -target=arduino-nano33 ./examples/espat/espconsole/main.go
+	tinygo build -size short -o ./build/test.elf -target=arduino-nano33 ./examples/espat/esphub/main.go
+	tinygo build -size short -o ./build/test.elf -target=arduino-nano33 ./examples/espat/espstation/main.go
 	tinygo build -size short -o ./build/test.elf -target=feather-m0 ./examples/gps/i2c/main.go
 	tinygo build -size short -o ./build/test.elf -target=feather-m0 ./examples/gps/uart/main.go
 	tinygo build -size short -o ./build/test.elf -target=microbit ./examples/hd44780/customchar/main.go
@@ -49,5 +50,6 @@ smoke-test:
 	tinygo build -size short -o ./build/test.elf -target=trinket-m0 ./examples/bme280/main.go
 	tinygo build -size short -o ./build/test.elf -target=circuitplay-express ./examples/microphone/main.go
 	tinygo build -size short -o ./build/test.elf -target=circuitplay-express ./examples/buzzer/main.go
+	tinygo build -size short -o ./build/test.elf -target=trinket-m0 ./examples/veml6070/main.go
 
 test: clean fmt-check smoke-test

README.md

@@ -82,6 +82,7 @@ func main() {
 | [ST7735 TFT color display](https://www.crystalfontz.com/controllers/Sitronix/ST7735R/319/) | SPI |
 | [ST7789 TFT color display](https://cdn-shop.adafruit.com/product-files/3787/3787_tft_QT154H2201__________20190228182902.pdf) | SPI |
 | [Thermistor](https://www.farnell.com/datasheets/33552.pdf) | ADC |
+| [VEML6070 UV light sensor](https://www.vishay.com/docs/84277/veml6070.pdf) | I2C |
 | [VL53L1X time-of-flight distance sensor](https://www.st.com/resource/en/datasheet/vl53l1x.pdf) | I2C |
 | [Waveshare 2.13" e-paper display](https://www.waveshare.com/w/upload/e/e6/2.13inch_e-Paper_Datasheet.pdf) | SPI |
 | [Waveshare 2.13" (B & C) e-paper display](https://www.waveshare.com/w/upload/d/d3/2.13inch-e-paper-b-Specification.pdf) | SPI |

apa102/apa102.go

@@ -21,15 +21,28 @@ const (
 
 // Device wraps APA102 SPI LEDs.
 type Device struct {
-	bus   machine.SPI
+	bus   SPI
 	Order int
 }
 
+// The SPI interface specifies the minimum functionality that a bus
+// implementation needs to provide for use by the APA102 driver.  Hardware
+// SPI from the TinyGo "machine" package implements this already.
+type SPI interface {
+	Tx(w, r []byte) error
+}
+
 // New returns a new APA102 driver. Pass in a fully configured SPI bus.
-func New(b machine.SPI) Device {
+func New(b SPI) Device {
 	return Device{bus: b, Order: BGR}
 }
 
+// NewSoftwareSPI returns a new APA102 driver that will use a software based
+// implementation of the SPI protocol.
+func NewSoftwareSPI(sckPin, mosiPin machine.Pin, delay uint32) Device {
+	return New(&bbSPI{SCK: sckPin, MOSI: mosiPin, Delay: delay})
+}
+
 // WriteColors writes the given RGBA color slice out using the APA102 protocol.
 // The A value (Alpha channel) is used for brightness, set to 0xff (255) for maximum.
 func (d Device) WriteColors(cs []color.RGBA) (n int, err error) {

apa102/softspi.go

@@ -0,0 +1,68 @@
+package apa102
+
+import "machine"
+
+// bbSPI is a dumb bit-bang implementation of SPI protocol that is hardcoded
+// to mode 0 and ignores trying to receive data. Just enough for the APA102.
+// Note: making this unexported for now because it is probable not suitable
+// most purposes other than the APA102 package. It might be desirable to make
+// this more generic and include it in the TinyGo "machine" package instead.
+type bbSPI struct {
+	SCK   machine.Pin
+	MOSI  machine.Pin
+	Delay uint32
+}
+
+// Configure sets up the SCK and MOSI pins as outputs and sets them low
+func (s *bbSPI) Configure() {
+	s.SCK.Configure(machine.PinConfig{Mode: machine.PinOutput})
+	s.MOSI.Configure(machine.PinConfig{Mode: machine.PinOutput})
+	s.SCK.Low()
+	s.MOSI.Low()
+	if s.Delay == 0 {
+		s.Delay = 1
+	}
+}
+
+// Tx matches signature of machine.SPI.Tx() and is used to send multiple bytes.
+// The r slice is ignored and no error will ever be returned.
+func (s *bbSPI) Tx(w []byte, r []byte) error {
+	s.Configure()
+	for _, b := range w {
+		s.Transfer(b)
+	}
+	return nil
+}
+
+// delay represents a quarter of the clock cycle
+func (s *bbSPI) delay() {
+	for i := uint32(0); i < s.Delay; {
+		i++
+	}
+}
+
+// Transfer is used to send a single byte.
+func (s *bbSPI) Transfer(b byte) {
+	for i := uint8(0); i < 8; i++ {
+
+		// half clock cycle high to start
+		s.SCK.High()
+		s.delay()
+
+		// write the value to MOSI (MSB first)
+		if b&(1<<(7-i)) == 0 {
+			s.MOSI.Low()
+		} else {
+			s.MOSI.High()
+		}
+		s.delay()
+
+		// half clock cycle low
+		s.SCK.Low()
+		s.delay()
+
+		// for actual SPI would try to read the MISO value here
+		s.delay()
+
+	}
+}

drivers.go

@@ -1,5 +1,5 @@
-// Package drivers provides a collection of hardware drivers for devices that
-// can be used together with TinyGo (https://tinygo.org).
+// Package drivers provides a collection of hardware drivers for TinyGo (https://tinygo.org)
+// for devices such as sensors and displays.
 //
 // Here is an example in TinyGo that uses the BMP180 digital barometer:
 //
@@ -9,7 +9,7 @@
 //		"time"
 //		"machine"
 //
-// 		"github.com/tinygo-org/drivers/bmp180"
+// 		"tinygo.org/x/drivers/bmp180"
 // 	)
 //
 // 	func main() {

easystepper/easystepper.go

@@ -1,4 +1,4 @@
-// Simple driver to rotate a 4-wire stepper motor
+// Package easystepper provides a simple driver to rotate a 4-wire stepper motor.
 package easystepper // import "tinygo.org/x/drivers/easystepper"
 
 import (

espat/mqtt/mqtt.go

@@ -1,3 +1,5 @@
+// Package mqtt is intended to provide compatible interfaces with the
+// Paho mqtt library.
 package mqtt
 
 import (

examples/apa102/itsybitsy-m0/main.go

@@ -0,0 +1,84 @@
+// This example demostrates how to control the "Dotstar" (APA102) LED included
+// on the Adafruit Itsy Bitsy M0 board.  It implements a "rainbow effect" based
+// on the following example:
+// https://github.com/adafruit/Adafruit_Learning_System_Guides/blob/master/CircuitPython_Essentials/CircuitPython_Internal_RGB_LED_rainbow.py
+package main
+
+import (
+	"image/color"
+	"machine"
+	"time"
+
+	"tinygo.org/x/drivers/apa102"
+)
+
+var (
+	apa apa102.Device
+
+	led   = machine.PWM{machine.LED}
+	leds  = make([]color.RGBA, 1)
+	wheel = &Wheel{Brightness: 0x10}
+)
+
+func init() {
+
+	// APA102 on Itsy Bitsy is connected to pins that require a software-based
+	// SPI implementation.
+	apa = apa102.NewSoftwareSPI(machine.PA00, machine.PA01, 1)
+
+	// Configure the regular on-board LED for PWM fading
+	machine.InitPWM()
+	led.Configure()
+
+}
+
+func main() {
+
+	// We'll fade the on-board LED in a goroutine to show/ensure that the APA102
+	// works fine with the scheduler enabled.  Comment this out to test this code
+	// with the scheduler disabled.
+	go func() {
+		for i, brightening := uint8(0), false; ; i++ {
+			if i == 0 {
+				brightening = !brightening
+				continue
+			}
+			var brightness uint16 = uint16(i) << 8
+			if !brightening {
+				brightness = 0xFFFF - brightness
+			}
+			led.Set(brightness)
+			time.Sleep(5 * time.Millisecond)
+		}
+	}()
+
+	// Use the "wheel" function from Adafruit's example to cycle the APA102
+	for {
+		leds[0] = wheel.Next()
+		apa.WriteColors(leds)
+		time.Sleep(25 * time.Millisecond)
+	}
+
+}
+
+// Wheel is a port of Adafruit's Circuit Python example referenced above.
+type Wheel struct {
+	Brightness uint8
+	pos        uint8
+}
+
+// Next increments the internal state of the color and returns the new RGBA
+func (w *Wheel) Next() (c color.RGBA) {
+	pos := w.pos
+	if w.pos < 85 {
+		c = color.RGBA{R: 0xFF - pos*3, G: pos * 3, B: 0x0, A: w.Brightness}
+	} else if w.pos < 170 {
+		pos -= 85
+		c = color.RGBA{R: 0x0, G: 0xFF - pos*3, B: pos * 3, A: w.Brightness}
+	} else {
+		pos -= 170
+		c = color.RGBA{R: pos * 3, G: 0x0, B: 0xFF - pos*3, A: w.Brightness}
+	}
+	w.pos++
+	return
+}

examples/espat/espconsole/main.go

@@ -23,11 +23,12 @@ const actAsAP = false
 const ssid = "YOURSSID"
 const pass = "YOURPASS"
 
+// these are the default pins for the Arduino Nano33 IoT.
 // change these to connect to a different UART or pins for the ESP8266/ESP32
 var (
-	uart = machine.UART1
-	tx   = machine.D10
-	rx   = machine.D11
+	uart = machine.UART2
+	tx   = machine.PA22
+	rx   = machine.PA23
 
 	console = machine.UART0
 

examples/espat/esphub/main.go

@@ -21,11 +21,12 @@ const actAsAP = false
 const ssid = "YOURSSID"
 const pass = "YOURPASS"
 
+// these are the default pins for the Arduino Nano33 IoT.
 // change these to connect to a different UART or pins for the ESP8266/ESP32
 var (
-	uart = machine.UART1
-	tx   = machine.D10
-	rx   = machine.D11
+	uart = machine.UART2
+	tx   = machine.PA22
+	rx   = machine.PA23
 
 	adaptor *espat.Device
 )

examples/espat/espstation/main.go

@@ -21,11 +21,12 @@ const pass = "YOURPASS"
 // IP address of the listener aka "hub". Replace with your own info.
 const hubIP = "0.0.0.0"
 
+// these are the default pins for the Arduino Nano33 IoT.
 // change these to connect to a different UART or pins for the ESP8266/ESP32
 var (
-	uart = machine.UART1
-	tx   = machine.D10
-	rx   = machine.D11
+	uart = machine.UART2
+	tx   = machine.PA22
+	rx   = machine.PA23
 
 	adaptor *espat.Device
 )

examples/espat/mqttclient/main.go

@@ -28,11 +28,12 @@ const pass = "YOURPASS"
 //const server = "tcp://test.mosquitto.org:1883"
 const server = "ssl://test.mosquitto.org:8883"
 
+// these are the default pins for the Arduino Nano33 IoT.
 // change these to connect to a different UART or pins for the ESP8266/ESP32
 var (
-	uart = machine.UART1
-	tx   = machine.D10
-	rx   = machine.D11
+	uart = machine.UART2
+	tx   = machine.PA22
+	rx   = machine.PA23
 
 	console = machine.UART0
 

examples/espat/tcpclient/main.go

@@ -21,9 +21,10 @@ const pass = "YOURPASS"
 // IP address of the server aka "hub". Replace with your own info.
 const serverIP = "0.0.0.0"
 
+// these are the default pins for the Arduino Nano33 IoT.
 // change these to connect to a different UART or pins for the ESP8266/ESP32
 var (
-	uart = machine.UART1
+	uart = machine.UART2
 	tx   = machine.PA22
 	rx   = machine.PA23
 

examples/lis3dh/main.go

@@ -11,7 +11,7 @@ import (
 var i2c = machine.I2C1
 
 func main() {
-	i2c.Configure(machine.I2CConfig{})
+	i2c.Configure(machine.I2CConfig{SCL: machine.SCL1_PIN, SDA: machine.SDA1_PIN})
 
 	accel := lis3dh.New(i2c)
 	accel.Address = lis3dh.Address1 // address on the Circuit Playground Express

examples/veml6070/main.go

@@ -0,0 +1,41 @@
+package main
+
+import (
+	"time"
+
+	"machine"
+
+	"tinygo.org/x/drivers/veml6070"
+)
+
+func main() {
+	machine.I2C0.Configure(machine.I2CConfig{})
+	sensor := veml6070.New(machine.I2C0)
+
+	if !sensor.Configure() {
+		println("VEML6070 could not be configured")
+		return
+	}
+
+	println("VEML6070 configured")
+
+	for {
+		intensity, _ := sensor.ReadUVALightIntensity()
+		println("UVA light intensity:", float32(intensity)/1000.0, "W/(m*m)")
+
+		switch sensor.GetEstimatedRiskLevel(intensity) {
+		case veml6070.UVI_RISK_LOW:
+			println("UV risk level: low")
+		case veml6070.UVI_RISK_MODERATE:
+			println("UV risk level: moderate")
+		case veml6070.UVI_RISK_HIGH:
+			println("UV risk level: high")
+		case veml6070.UVI_RISK_VERY_HIGH:
+			println("UV risk level: very high")
+		case veml6070.UVI_RISK_EXTREME:
+			println("UV risk level: extreme")
+		}
+
+		time.Sleep(2 * time.Second)
+	}
+}

ssd1331/ssd1331.go

@@ -34,7 +34,7 @@ type Config struct {
 	Height int16
 }
 
-// New creates a new ST7735 connection. The SPI wire must already be configured.
+// New creates a new SSD1331 connection. The SPI wire must already be configured.
 func New(bus machine.SPI, resetPin, dcPin, csPin machine.Pin) Device {
 	dcPin.Configure(machine.PinConfig{Mode: machine.PinOutput})
 	resetPin.Configure(machine.PinConfig{Mode: machine.PinOutput})
@@ -250,21 +250,8 @@ func (d *Device) Data(data uint8) {
 
 // Tx sends data to the display
 func (d *Device) Tx(data []byte, isCommand bool) {
-	if isCommand {
-		d.csPin.High()
-		d.dcPin.Low()
-		d.csPin.Low()
-
-		d.bus.Tx(data, nil)
-		d.csPin.High()
-	} else {
-		d.csPin.High()
-		d.dcPin.High()
-		d.csPin.Low()
-
-		d.bus.Tx(data, nil)
-		d.csPin.High()
-	}
+	d.dcPin.Set(!isCommand)
+	d.bus.Tx(data, nil)
 }
 
 // Size returns the current size of the display.

st7735/st7735.go

@@ -383,21 +383,8 @@ func (d *Device) Data(data uint8) {
 
 // Tx sends data to the display
 func (d *Device) Tx(data []byte, isCommand bool) {
-	if isCommand {
-		d.csPin.High()
-		d.dcPin.Low()
-		d.csPin.Low()
-
-		d.bus.Tx(data, nil)
-		d.csPin.High()
-	} else {
-		d.csPin.High()
-		d.dcPin.High()
-		d.csPin.Low()
-
-		d.bus.Tx(data, nil)
-		d.csPin.High()
-	}
+	d.dcPin.Set(!isCommand)
+	d.bus.Tx(data, nil)
 }
 
 // Size returns the current size of the display.

veml6070/registers.go

@@ -0,0 +1,65 @@
+package veml6070
+
+// I2C addresses and other constants
+
+const (
+	ADDR_L = 0x38 // 7bit address of the VEML6070 (write, read)
+	ADDR_H = 0x39 // 7bit address of the VEML6070 (read)
+)
+
+// Some possible values for resistance value (in ohm) of VEML6070 calibration resistor
+const (
+	RSET_240K = 240000
+	RSET_270K = 270000
+	RSET_300K = 300000
+	RSET_600K = 600000
+)
+
+// Possible values for integration time of VEML6070
+// (internally represents the config register bit mask)
+const (
+	IT_HALF = 0x00
+	IT_1    = 0x04
+	IT_2    = 0x08
+	IT_4    = 0x0C
+)
+
+// Possible values for UVI (UV index) risk level estimations - the VEML6070 can
+// only estimate UVI risk levels since it can only sense UVA rays but the vendor
+// tried to come up with some coarse thresholds, from application notes
+const (
+	UVI_RISK_LOW = iota
+	UVI_RISK_MODERATE
+	UVI_RISK_HIGH
+	UVI_RISK_VERY_HIGH
+	UVI_RISK_EXTREME
+)
+
+// Scale factor in milliseconds / ohm to determine refresh time
+// (aka sampling time) without IT_FACTOR for any given RSET, from datasheet.
+// Note: 100.0 milliseconds are applicable for RSET=240 kOhm and IT_FACTOR=1
+const RSET_TO_REFRESHTIME_SCALE = 100.0 / RSET_240K
+
+// The refresh time in milliseconds for which NORMALIZED_UVA_SENSITIVITY
+// is applicable to a step count
+const NORMALIZED_REFRESHTIME = 100.0
+
+// The UVA sensitivity in mW/(m*m)/step which is applicable to a step count
+// normalized to the NORMALIZED_REFRESHTIME, from datasheet for RSET=240 kOhm
+// and IT_FACTOR=1
+const NORMALIZED_UVA_SENSITIVITY = 50.0
+
+// Config register
+
+// Possible values for shutdown
+const (
+	CONFIG_SD_DISABLE = 0x00
+	CONFIG_SD_ENABLE  = 0x01
+)
+
+// Enable / disable
+const (
+	CONFIG_DEFAULTS = 0x02
+	CONFIG_ENABLE   = CONFIG_SD_DISABLE | CONFIG_DEFAULTS
+	CONFIG_DISABLE  = CONFIG_SD_ENABLE | CONFIG_DEFAULTS
+)

veml6070/veml6070.go

@@ -0,0 +1,140 @@
+// Package veml6070 provides a driver for the VEML6070 digital UV light sensor
+// by Vishay.
+//
+// Datasheet:
+// https://www.vishay.com/docs/84277/veml6070.pdf
+// Application Notes:
+// https://www.vishay.com/docs/84310/designingveml6070.pdf
+//
+package veml6070 // import "tinygo.org/x/drivers/veml6070"
+
+import (
+	"time"
+
+	"machine"
+)
+
+// Device wraps an I2C connection to a VEML6070 device.
+type Device struct {
+	bus         machine.I2C
+	AddressLow  uint16
+	AddressHigh uint16
+	RSET        uint32
+	IT          uint8
+}
+
+// New creates a new VEML6070 connection. The I2C bus must already be
+// configured.
+//
+// This function only creates the Device object, it does not initialize the device.
+// You must call Configure() first in order to use the device itself.
+func New(bus machine.I2C) Device {
+	return Device{
+		bus:         bus,
+		AddressLow:  ADDR_L,
+		AddressHigh: ADDR_H,
+		RSET:        RSET_240K,
+		// Note: default to maximum to get as much precision as possible since
+		// raw data values larger than 16 bit can hardly occur with RSET below
+		// 300 kOhm in real world applications. Power saving due to shorter
+		// sampling time might be a reason to reduce this.
+		IT: IT_4,
+	}
+}
+
+// Configure sets up the device for communication
+func (d *Device) Configure() bool {
+	// save power by shutdown as early as possible, also serves as presence test
+	if err := d.disable(); err != nil {
+		return false
+	}
+
+	return true
+}
+
+// ReadUVALightIntensity returns the UVA light intensity (irradiance)
+// in milli Watt per square meter (mW/(m*m))
+func (d *Device) ReadUVALightIntensity() (uint32, error) {
+	var err2 error
+
+	if err := d.enable(); err != nil {
+		return 0, err
+	}
+
+	// wait two times the refresh time to allow completion of a previous cycle
+	// with old settings (worst case)
+	time.Sleep(time.Duration(d.getRefreshTime()) * 2 * time.Millisecond)
+
+	msb, err2 := d.readData(d.AddressHigh)
+	if err2 != nil {
+		return 0, err2
+	}
+
+	lsb, err2 := d.readData(d.AddressLow)
+	if err2 != nil {
+		return 0, err2
+	}
+
+	if err := d.disable(); err != nil {
+		return 0, err
+	}
+
+	rawData := (uint32(msb) << 8) | uint32(lsb)
+
+	// normalize raw data (step count sampled in d.getRefreshTime()) into the
+	// linearly scaled normalized data (step count sampled in 100ms) for which
+	// we know the UVA sensitivity
+	normalizedData := float32(rawData) * NORMALIZED_REFRESHTIME / d.getRefreshTime()
+
+	// now we can calculate the absolute UVA power detected combining normalized
+	// data with known UVA sensitivity for this data, from datasheet
+	intensity := normalizedData * NORMALIZED_UVA_SENSITIVITY // mW/(m*m)
+
+	return uint32(intensity + 0.5), nil
+}
+
+// GetEstimatedRiskLevel returns estimated risk level from comparing UVA light
+// intensity values in mW/(m*m) with thresholds calculated from application notes
+func (d *Device) GetEstimatedRiskLevel(intensity uint32) uint8 {
+	if intensity <= 24888 {
+		return UVI_RISK_LOW
+	} else if intensity <= 49800 {
+		return UVI_RISK_MODERATE
+	} else if intensity <= 66400 {
+		return UVI_RISK_HIGH
+	} else if intensity <= 91288 {
+		return UVI_RISK_VERY_HIGH
+	} else {
+		return UVI_RISK_EXTREME
+	}
+}
+
+func (d *Device) disable() error {
+	return d.bus.Tx(uint16(d.AddressLow), []byte{CONFIG_DISABLE}, nil)
+}
+
+func (d *Device) enable() error {
+	return d.bus.Tx(uint16(d.AddressLow), []byte{CONFIG_ENABLE | d.IT}, nil)
+}
+
+func (d *Device) readData(address uint16) (byte, error) {
+	data := []byte{0}
+	err := machine.I2C0.Tx(address, []byte{}, data)
+	return data[0], err
+}
+
+// getRefreshTime returns the refresh time (aka sample time) in milliseconds
+func (d *Device) getRefreshTime() float32 {
+	var it float32
+	switch d.IT {
+	case IT_HALF:
+		it = 0.5
+	case IT_1:
+		it = 1
+	case IT_2:
+		it = 2
+	case IT_4:
+		it = 4
+	}
+	return float32(d.RSET) * RSET_TO_REFRESHTIME_SCALE * it
+}

version.go

@@ -0,0 +1,5 @@
+package drivers
+
+// Version returns a user-readable string showing the version of the drivers package for support purposes.
+// Update this value before release of new version of software.
+const Version = "0.7.0"