mirror of https://github.com/periph/devices
adxl345: Driver, initial commit for review. (#66)
Accelerator sensor. Supports SPI, designed to support I2C in the future.pull/71/head
Benoit Pereira da Silva
2 years ago
committed by
GitHub
parent
c14e02d418
commit
931687b33a
@ -0,0 +1,250 @@
|
||||
// Copyright 2023 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 adxl345
|
||||
|
||||
import (
|
||||
"encoding/binary"
|
||||
"fmt"
|
||||
"periph.io/x/conn/v3/physic"
|
||||
"periph.io/x/conn/v3/spi"
|
||||
)
|
||||
|
||||
type Sensitivity byte
|
||||
|
||||
// The following constants are register used by the ADXL345
|
||||
// Check the table 19 of the datasheet for more details.
|
||||
// https://www.analog.com/media/en/technical-documentation/data-sheets/ADXL345.pdf
|
||||
const (
|
||||
DeviceID = 0x00 // Device ID, expected to be 0xE5 when using ADXL345
|
||||
|
||||
ThreshTap = 0x1D // Tap threshold
|
||||
OfsX = 0x1E // X-axis offset
|
||||
OfsY = 0x1F // Y-axis offset
|
||||
OfsZ = 0x20 // Z-axis offset
|
||||
Dur = 0x21 // Tap duration
|
||||
Latent = 0x22 // Tap latency
|
||||
Window = 0x23 // Tap window
|
||||
ThreshAct = 0x24 // Activity threshold
|
||||
ThreshInact = 0x25 // Inactivity threshold
|
||||
TimeInact = 0x26 // Inactivity time
|
||||
ActInactCtl = 0x27 // Axis control for activity/inactivity detection
|
||||
ThreshFf = 0x28 // Free-fall threshold
|
||||
TapAxes = 0x2A // Axis control for single tap/double tap
|
||||
TapStatus = 0x2B // Source of single tap/double tap
|
||||
ActivityStatus = 0x2A // Source of activity detection
|
||||
InactivityStatus = 0x2B // Source of inactivity detection
|
||||
|
||||
// Control registers
|
||||
|
||||
BwRate = 0x2C // Data rate and power mode control
|
||||
PowerCtl = 0x2D // Power saving features control
|
||||
IntEnable = 0x2E // Interrupt enable control
|
||||
IntMap = 0x2F // Interrupt mapping control
|
||||
IntSource = 0x30 // Source of interrupts
|
||||
DataFormat = 0x31 // Data format control
|
||||
|
||||
// Data registers
|
||||
DataX0 = 0x32 // X-Axis Data 0
|
||||
DataX1 = 0x33 // X-Axis Data 1
|
||||
DataY0 = 0x34 // Y-Axis Data 0
|
||||
DataY1 = 0x35 // Y-Axis Data 1
|
||||
DataZ0 = 0x36 // Z-Axis Data 0
|
||||
DataZ1 = 0x37 // Z-Axis Data 1
|
||||
|
||||
// FIFO control
|
||||
FifoCtl = 0x38 // FIFO control
|
||||
FifoStatus = 0x39 // FIFO status
|
||||
|
||||
)
|
||||
|
||||
// Sensitivity constants represents the sensitivity of the ADXL345.
|
||||
// The ADXL345 supports 4 sensitivity settings, ±2g, ±4g, ±8g, and ±16g, with the default being ±2g.
|
||||
// Sensitivity is an option that can be set at initialization in Opts.
|
||||
// You can set the sensitivity of the ADXL345 with the DataFormat register.
|
||||
const (
|
||||
S2G Sensitivity = 0x00 // Sensitivity at 2g
|
||||
S4G Sensitivity = 0x01 // Sensitivity at 4g
|
||||
S8G Sensitivity = 0x02 // Sensitivity at 8g
|
||||
S16G Sensitivity = 0x03 // Sensitivity at 16g
|
||||
)
|
||||
|
||||
var (
|
||||
SpiFrequency = physic.MegaHertz * 2
|
||||
SpiMode = spi.Mode3 // Defines the base clock signal, along with the polarity and phase of the data signal.
|
||||
SpiBits = 8
|
||||
)
|
||||
|
||||
var DefaultOpts = Opts{
|
||||
ExpectedDeviceID: 0xE5,
|
||||
Sensitivity: S2G,
|
||||
}
|
||||
|
||||
type Opts struct {
|
||||
ExpectedDeviceID byte // Expected device ID used to verify that the device is an ADXL345.
|
||||
Sensitivity Sensitivity // Sensitivity of the device (2G, 4G, 8G, 16G)
|
||||
}
|
||||
|
||||
// Dev is a driver for the ADXL345 accelerometer
|
||||
// It uses the SPI interface to communicate with the device.
|
||||
type Dev struct {
|
||||
name string
|
||||
s spi.Conn
|
||||
// The sensitivity of the device (2G, 4G, 8G, 16G)
|
||||
// Set to 2G by default, can be changed in the Opts at initialization.
|
||||
sensitivity Sensitivity
|
||||
}
|
||||
|
||||
func (d *Dev) String() string {
|
||||
return fmt.Sprintf("ADXL345{Sensitivity:%s}", d.sensitivity)
|
||||
}
|
||||
|
||||
// NewSpi creates a new ADXL345 Dev with a spi connection or returns an error.
|
||||
// The bus and chip parameters define the SPI bus and chip select to use.
|
||||
// The SPI s is configured.
|
||||
// The device is turned on.
|
||||
// The device is verified to be an ADXL345.
|
||||
func NewSpi(p spi.Port, o *Opts) (*Dev, error) {
|
||||
// Convert the spi.Port into a spi.Conn so it can be used for communication.
|
||||
c, err := p.Connect(SpiFrequency, SpiMode, SpiBits)
|
||||
if err != nil {
|
||||
return nil, err
|
||||
}
|
||||
d := &Dev{
|
||||
name: "ADXL345",
|
||||
s: c,
|
||||
}
|
||||
err = d.TurnOn()
|
||||
if err != nil {
|
||||
return nil, err
|
||||
}
|
||||
if o.Sensitivity != S2G { // default
|
||||
err = d.setSensitivity(o.Sensitivity)
|
||||
if err != nil {
|
||||
return nil, err
|
||||
}
|
||||
}
|
||||
// Verify that the device is an ADXL345.
|
||||
rx, _ := d.ReadRaw(DeviceID)
|
||||
if rx[1] != o.ExpectedDeviceID {
|
||||
return nil, fmt.Errorf("wrong device connected should be an adxl345 should be\"%#x\" rx0=\"%#x\" rx1=\"%#x\"", o.ExpectedDeviceID, rx[0], rx[1])
|
||||
}
|
||||
return d, nil
|
||||
}
|
||||
|
||||
// SetSensitivity sets the sensitivity of the ADXL345.
|
||||
// The sensitivity parameter should be one of 2, 4, 8, or 16, representing ±2g, ±4g, ±8g, or ±16g respectively.
|
||||
func (d *Dev) setSensitivity(sensitivity Sensitivity) error {
|
||||
switch sensitivity {
|
||||
case S2G, S4G, S8G, S16G:
|
||||
// Write to the DataFormat register
|
||||
d.sensitivity = sensitivity
|
||||
return d.Write(DataFormat, byte(sensitivity))
|
||||
default:
|
||||
return fmt.Errorf("invalid sensitivity: %d. Valid values are 2, 4, 8, 16", sensitivity)
|
||||
}
|
||||
}
|
||||
|
||||
// TurnOn turns on the measurement mode of the ADXL345.
|
||||
// This is required before reading data from the device.
|
||||
func (d *Dev) TurnOn() error {
|
||||
return d.Write(PowerCtl, 0x08)
|
||||
}
|
||||
|
||||
// TurnOff turns off the measurement mode of the ADXL345.
|
||||
func (d *Dev) TurnOff() error {
|
||||
return d.Write(PowerCtl, 0x00)
|
||||
}
|
||||
|
||||
// Update reads the acceleration values from the ADXL345.
|
||||
// By reading the acceleration the 3 axes acceleration values.
|
||||
// This is a simple synchronous implementation.
|
||||
func (d *Dev) Update() Acceleration {
|
||||
return Acceleration{
|
||||
X: d.ReadAndCombine(DataX0, DataX1),
|
||||
Y: d.ReadAndCombine(DataY0, DataY1),
|
||||
Z: d.ReadAndCombine(DataZ0, DataZ1),
|
||||
}
|
||||
}
|
||||
|
||||
// ReadAndCombine combines two registers to form a 16-bit value.
|
||||
// The ADXL345 uses two 8-bit registers to store the output data for each axis.
|
||||
// X := d.ReadAndCombine(DataX0, DataX1) where:
|
||||
// `DataX0` is the address of the lower byte (LSB, least significant byte)
|
||||
// `DataX1` is the address of the upper byte (MSB, most significant byte)
|
||||
// The ADXL345 combines both registers to deliver 16-bit output for each acceleration axis.
|
||||
// A similar approach is used for the Y and Z axes. This technique provides higher precision in the measurements.
|
||||
func (d *Dev) ReadAndCombine(reg1, reg2 byte) int16 {
|
||||
low, _ := d.Read(reg1)
|
||||
high, _ := d.Read(reg2)
|
||||
|
||||
return int16(uint16(high)<<8) | int16(low)
|
||||
}
|
||||
|
||||
// Read reads a 16-bit value from the specified register address.
|
||||
func (d *Dev) Read(regAddress byte) (int16, error) {
|
||||
tx := []byte{regAddress | 0x80, 0x00}
|
||||
rx := make([]byte, len(tx))
|
||||
err := d.s.Tx(tx, rx)
|
||||
if err != nil {
|
||||
return 0, err
|
||||
}
|
||||
return int16(binary.LittleEndian.Uint16(rx)), nil
|
||||
}
|
||||
|
||||
// ReadRaw reads a []byte value from the specified register address.
|
||||
func (d *Dev) ReadRaw(regAddress byte) ([]byte, error) {
|
||||
// Send a two-byte sequence:
|
||||
// - The first byte contains the address with bit 7 set high to indicate read op
|
||||
// - The second byte is a "don't care" value, usually zero
|
||||
tx := []byte{regAddress | 0x80, 0x00}
|
||||
rx := make([]byte, len(tx))
|
||||
err := d.s.Tx(tx, rx)
|
||||
return rx, err
|
||||
}
|
||||
|
||||
// Write writes a 1 byte value to the specified register address.
|
||||
func (d *Dev) Write(regAddress byte, value byte) error {
|
||||
// Prepare a 2-byte buffer with the register address and the desired value.
|
||||
tx := []byte{regAddress, value}
|
||||
// Prepare a receiving buffer of the same size as the transmit buffer.
|
||||
rx := make([]byte, len(tx))
|
||||
// Perform the transfer. We expect the SPI device to write back an acknowledgement.
|
||||
err := d.s.Tx(tx, rx)
|
||||
return err
|
||||
}
|
||||
|
||||
// Acceleration represents the acceleration on the three axes X,Y,Z.
|
||||
// The sensitivity can be set to different levels: ±2g, ±4g, ±8g, or ±16g. (S2G, S4G, S8G, S16G)
|
||||
// The output are 16-bit integers, so the device measures between -32768 and +32767 for each axis.
|
||||
// For example, if the sensitivity is set to ±2g and you're getting a reading of 16384 on the X axis, that would correspond to 1g of acceleration along the X axis.
|
||||
// To convert the raw values to a physical unit (like g or m/s²), you would need to know the sensitivity setting of your device.
|
||||
// For instance, if your sensitivity is set to ±2g, the conversion factor would be 2 / 32768 = 0.000061g per count.
|
||||
// So, you would multiply the raw acceleration values by this factor to get the acceleration in `g`.
|
||||
type Acceleration struct {
|
||||
X int16
|
||||
Y int16
|
||||
Z int16
|
||||
}
|
||||
|
||||
// String returns a string representation of the Acceleration
|
||||
func (a Acceleration) String() string {
|
||||
return fmt.Sprintf("X:%d Y:%d Z:%d", a.X, a.Y, a.Z)
|
||||
}
|
||||
|
||||
// Sensitivity returns the sensitivity of the device as a human-readable string.
|
||||
func (s Sensitivity) String() string {
|
||||
switch s {
|
||||
case S2G:
|
||||
return "+/-2g"
|
||||
case S4G:
|
||||
return "+/-4g"
|
||||
case S8G:
|
||||
return "+/-8g"
|
||||
case S16G:
|
||||
return "+/-16g"
|
||||
default:
|
||||
return "unsupported"
|
||||
}
|
||||
}
|
||||
@ -0,0 +1,10 @@
|
||||
// Copyright 2032 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 adxl345 controls an ADXL345 3-axis accelerometer over SPI.
|
||||
//
|
||||
// # Datasheet
|
||||
//
|
||||
// http://www.analog.com/media/en/technical-documentation/data-sheets/ADXL345.pdf
|
||||
package adxl345
|
||||
@ -0,0 +1,56 @@
|
||||
// Copyright 2023 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 example
|
||||
|
||||
import (
|
||||
"fmt"
|
||||
"log"
|
||||
"periph.io/x/conn/v3/spi/spireg"
|
||||
"periph.io/x/devices/v3/adxl345"
|
||||
"periph.io/x/host/v3"
|
||||
"time"
|
||||
)
|
||||
|
||||
// Example reads the acceleration values every 30ms for 3 seconds.
|
||||
func Example() {
|
||||
|
||||
// Initialize the host
|
||||
// Make sure periph is initialized.
|
||||
if _, err := host.Init(); err != nil {
|
||||
log.Fatal(err)
|
||||
}
|
||||
|
||||
// Use spireg SPI port registry to find the first available SPI bus.
|
||||
p, err := spireg.Open("")
|
||||
if err != nil {
|
||||
log.Fatal(err)
|
||||
}
|
||||
|
||||
defer p.Close()
|
||||
|
||||
d, err := adxl345.NewSpi(p, &adxl345.DefaultOpts)
|
||||
if err != nil {
|
||||
panic(err)
|
||||
}
|
||||
|
||||
fmt.Println(d.String())
|
||||
|
||||
// use a ticker to read the acceleration values every 200ms
|
||||
ticker := time.NewTicker(30 * time.Millisecond)
|
||||
defer ticker.Stop()
|
||||
|
||||
// stop after 3 seconds
|
||||
stop := time.After(3 * time.Second)
|
||||
|
||||
for {
|
||||
select {
|
||||
case <-stop:
|
||||
return
|
||||
case <-ticker.C:
|
||||
a := d.Update()
|
||||
fmt.Println(a)
|
||||
}
|
||||
}
|
||||
}
|
||||
Loading…
Reference in New Issue