mirror of
https://github.com/tinygo-org/drivers.git
synced 2026-08-08 00:43:39 +00:00
Ayke van Laethem
6763521eff
This type should be used whenever a sensor (or actuator?) works with a
temperature. For example, this commit changes the signature:
ReadTemperature() (int32, error)
to the following:
ReadTemperature() (drivers.Temperature, error)
I believe this is much clearer in intent. It also makes it trivial to
introduce common conversions. For example, there are already Celsius()
and Fahrenheit() methods to convert to the given units, as a floating
point. More units could be added as needed, for example a CelsiusInt().
74 lines
2.2 KiB
Go
74 lines
2.2 KiB
Go
// Package sht3x provides a driver for the SHT3x digital humidity sensor
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// series by Sensirion.
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//
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// Datasheet:
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// https://www.sensirion.com/fileadmin/user_upload/customers/sensirion/Dokumente/0_Datasheets/Humidity/Sensirion_Humidity_Sensors_SHT3x_Datasheet_digital.pdf
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//
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package sht3x // import "tinygo.org/x/drivers/sht3x"
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import (
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"time"
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"tinygo.org/x/drivers"
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)
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// Device wraps an I2C connection to a SHT31 device.
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type Device struct {
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bus drivers.I2C
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Address uint16
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}
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// New creates a new SHT31 connection. The I2C bus must already be
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// configured.
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//
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// This function only creates the Device object, it does not initialize the device.
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// You must call Configure() first in order to use the device itself.
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func New(bus drivers.I2C) Device {
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return Device{
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bus: bus,
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Address: AddressA,
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}
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}
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// Read returns the temperature in celsius milli degrees (°C/1000).
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func (d *Device) ReadTemperature() (tempMilliCelsius drivers.Temperature, err error) {
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tempMilliCelsius, _, err = d.ReadTemperatureHumidity()
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return drivers.Temperature(tempMilliCelsius), err
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}
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// Read returns the relative humidity in hundredths of a percent.
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func (d *Device) ReadHumidity() (relativeHumidity int16, err error) {
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_, relativeHumidity, err = d.ReadTemperatureHumidity()
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return relativeHumidity, err
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}
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// Read returns both the temperature and relative humidity.
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func (d *Device) ReadTemperatureHumidity() (tempMilliCelsius drivers.Temperature, relativeHumidity int16, err error) {
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var rawTemp, rawHum, errx = d.rawReadings()
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if errx != nil {
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err = errx
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return
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}
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tempMilliCelsius = drivers.Temperature((35000 * int32(rawTemp) / 13107) - 45000)
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relativeHumidity = int16(2000 * int32(rawHum) / 13107)
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return
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}
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// rawReadings returns the sensor's raw values of the temperature and humidity
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func (d *Device) rawReadings() (uint16, uint16, error) {
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d.bus.Tx(d.Address, []byte{MEASUREMENT_COMMAND_MSB, MEASUREMENT_COMMAND_LSB}, nil)
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time.Sleep(17 * time.Millisecond)
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var data [5]byte
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d.bus.Tx(d.Address, []byte{}, data[:])
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// ignore crc for now
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return readUint(data[0], data[1]), readUint(data[3], data[4]), nil
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}
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// readUint converts two bytes to uint16
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func readUint(msb byte, lsb byte) uint16 {
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return (uint16(msb) << 8) | uint16(lsb)
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}
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