lis3dh: implement accelerometer functionality

Signed-off-by: Ron Evans <ron@hybridgroup.com>
2026-07-26 10:38:41 +00:00 · 2019-04-15 19:15:58 +02:00
parent 720097ebad
commit c0cadf8d82
5 changed files with 237 additions and 0 deletions
@@ -21,6 +21,7 @@ jobs:
      - run: tinygo build -size short -o test.elf -target=itsybitsy-m0 ./examples/ds3231/main.go
      - run: tinygo build -size short -o test.elf -target=microbit ./examples/easystepper/main.go
      - run: tinygo build -size short -o test.elf -target=itsybitsy-m0 ./examples/espat/esphub/main.go
+      - run: tinygo build -size short -o test.elf -target=circuitplay-express ./examples/lis3dh/main.go
      - run: tinygo build -size short -o test.elf -target=itsybitsy-m0 ./examples/mag3110/main.go
      - run: tinygo build -size short -o test.elf -target=itsybitsy-m0 ./examples/mma8653/main.go
      - run: tinygo build -size short -o test.elf -target=itsybitsy-m0 ./examples/mpu6050/main.go
@@ -62,6 +62,7 @@ func main() {
 | [DS3231 real time clock](https://datasheets.maximintegrated.com/en/ds/DS3231.pdf) | I2C |
 | ["Easystepper" stepper motor controller](https://en.wikipedia.org/wiki/Stepper_motor) | GPIO |
 | [ESP8266/ESP32 AT Command set for WiFi/TCP/UDP](https://github.com/espressif/esp32-at) | UART |
+| [LIS3DH accelerometer](https://www.st.com/resource/en/datasheet/lis3dh.pdf) | I2C |
 | [MAG3110 magnetometer](https://www.nxp.com/docs/en/data-sheet/MAG3110.pdf) | I2C |
 | [MMA8653 accelerometer](https://www.nxp.com/docs/en/data-sheet/MMA8653FC.pdf) | I2C |
 | [MPU6050 accelerometer/gyroscope](https://store.invensense.com/datasheets/invensense/MPU-6050_DataSheet_V3%204.pdf) | I2C |
@@ -0,0 +1,32 @@
+// Connects to a LIS3DH I2C accelerometer on the Adafruit Circuit Playground Express.
+package main
+
+import (
+	"machine"
+	"time"
+
+	"github.com/tinygo-org/drivers/lis3dh"
+)
+
+var i2c = machine.I2C1
+
+func main() {
+	i2c.Configure(machine.I2CConfig{})
+
+	accel := lis3dh.New(i2c)
+	accel.Address = lis3dh.Address1 // address on the Circuit Playground Express
+	accel.Configure()
+	accel.SetRange(lis3dh.RANGE_2_G)
+
+	println(accel.Connected())
+
+	for {
+		x, y, z, _ := accel.ReadAcceleration()
+		println("X:", x, "Y:", y, "Z:", z)
+
+		rx, ry, rz := accel.ReadRawAcceleration()
+		println("X (raw):", rx, "Y (raw):", ry, "Z (raw):", rz)
+
+		time.Sleep(time.Millisecond * 100)
+	}
+}
@@ -0,0 +1,126 @@
+// Package lis3dh provides a driver for the LIS3DH digital accelerometer.
+//
+// Datasheet: https://www.st.com/resource/en/datasheet/lis3dh.pdf
+package lis3dh
+
+import (
+	"machine"
+)
+
+// Device wraps an I2C connection to a LIS3DH device.
+type Device struct {
+	bus     machine.I2C
+	Address uint16
+	r       Range
+}
+
+// New creates a new LIS3DH connection. The I2C bus must already be configured.
+//
+// This function only creates the Device object, it does not touch the device.
+func New(bus machine.I2C) Device {
+	return Device{bus: bus, Address: Address0}
+}
+
+// Configure sets up the device for communication
+func (d *Device) Configure() {
+	// enable all axes, normal mode
+	d.bus.WriteRegister(uint8(d.Address), REG_CTRL1, []byte{0x07})
+
+	// 400Hz rate
+	d.SetDataRate(DATARATE_400_HZ)
+
+	// High res & BDU enabled
+	d.bus.WriteRegister(uint8(d.Address), REG_CTRL4, []byte{0x88})
+
+	// get current range
+	d.r = d.ReadRange()
+}
+
+// Connected returns whether a LIS3DH has been found.
+// It does a "who am I" request and checks the response.
+func (d *Device) Connected() bool {
+	data := []byte{0}
+	err := d.bus.ReadRegister(uint8(d.Address), WHO_AM_I, data)
+	if err != nil {
+		return false
+	}
+	return data[0] == 0x33
+}
+
+// SetDataRate sets the speed of data collected by the LIS3DH.
+func (d *Device) SetDataRate(rate DataRate) {
+	ctl1 := []byte{0}
+	err := d.bus.ReadRegister(uint8(d.Address), REG_CTRL1, ctl1)
+	if err != nil {
+		println(err.Error())
+	}
+	// mask off bits
+	ctl1[0] &^= 0xf0
+	ctl1[0] |= (byte(rate) << 4)
+	d.bus.WriteRegister(uint8(d.Address), REG_CTRL1, ctl1)
+}
+
+// SetRange sets the G range for LIS3DH.
+func (d *Device) SetRange(r Range) {
+	ctl := []byte{0}
+	err := d.bus.ReadRegister(uint8(d.Address), REG_CTRL4, ctl)
+	if err != nil {
+		println(err.Error())
+	}
+	// mask off bits
+	ctl[0] &^= 0x30
+	ctl[0] |= (byte(r) << 4)
+	d.bus.WriteRegister(uint8(d.Address), REG_CTRL4, ctl)
+
+	// store the new range
+	d.r = r
+}
+
+// ReadRange returns the current G range for LIS3DH.
+func (d *Device) ReadRange() (r Range) {
+	ctl := []byte{0}
+	err := d.bus.ReadRegister(uint8(d.Address), REG_CTRL4, ctl)
+	if err != nil {
+		println(err.Error())
+	}
+	// mask off bits
+	r = Range(ctl[0] >> 4)
+	r &= 0x03
+
+	return r
+}
+
+// ReadAcceleration reads the current acceleration from the device and returns
+// it in µg (micro-gravity). When one of the axes is pointing straight to Earth
+// and the sensor is not moving the returned value will be around 1000000 or
+// -1000000.
+func (d *Device) ReadAcceleration() (int32, int32, int32, error) {
+	x, y, z := d.ReadRawAcceleration()
+	divider := float32(1)
+	switch d.r {
+	case RANGE_16_G:
+		divider = 1365
+	case RANGE_8_G:
+		divider = 4096
+	case RANGE_4_G:
+		divider = 8190
+	case RANGE_2_G:
+		divider = 16380
+	}
+
+	return int32(float32(x) / divider * 1000000), int32(float32(y) / divider * 1000000), int32(float32(z) / divider * 1000000), nil
+}
+
+// ReadRawAcceleration returns the raw x, y and z axis from the LIS3DH
+func (d *Device) ReadRawAcceleration() (x int16, y int16, z int16) {
+	d.bus.WriteRegister(uint8(d.Address), REG_OUT_X_L|0x80, nil)
+
+	data := []byte{0, 0, 0, 0, 0, 0}
+	d.bus.Tx(d.Address, nil, data)
+
+	x = int16((uint16(data[1]) << 8) | uint16(data[0]))
+	y = int16((uint16(data[3]) << 8) | uint16(data[2]))
+	z = int16((uint16(data[5]) << 8) | uint16(data[4]))
+
+	return
+}
@@ -0,0 +1,77 @@
+package lis3dh
+
+// Constants/addresses used for I2C.
+
+// The I2C addresses which this device listens to.
+const (
+	Address0 = 0x18 // SA0 is low
+	Address1 = 0x19 // SA0 is high
+)
+
+// Registers. Names, addresses and comments copied from the datasheet.
+const (
+	WHO_AM_I      = 0x0F
+	REG_STATUS1   = 0x07
+	REG_OUTADC1_L = 0x08
+	REG_OUTADC1_H = 0x09
+	REG_OUTADC2_L = 0x0A
+	REG_OUTADC2_H = 0x0B
+	REG_OUTADC3_L = 0x0C
+	REG_OUTADC3_H = 0x0D
+	REG_INTCOUNT  = 0x0E
+	REG_WHOAMI    = 0x0F
+	REG_TEMPCFG   = 0x1F
+	REG_CTRL1     = 0x20
+	REG_CTRL2     = 0x21
+	REG_CTRL3     = 0x22
+	REG_CTRL4     = 0x23
+	REG_CTRL5     = 0x24
+	REG_CTRL6     = 0x25
+	REG_REFERENCE = 0x26
+	REG_STATUS2   = 0x27
+	REG_OUT_X_L   = 0x28
+	REG_OUT_X_H   = 0x29
+	REG_OUT_Y_L   = 0x2A
+	REG_OUT_Y_H   = 0x2B
+	REG_OUT_Z_L   = 0x2C
+	REG_OUT_Z_H   = 0x2D
+	REG_FIFOCTRL  = 0x2E
+	REG_FIFOSRC   = 0x2F
+	REG_INT1CFG   = 0x30
+	REG_INT1SRC   = 0x31
+	REG_INT1THS   = 0x32
+	REG_INT1DUR   = 0x33
+	REG_CLICKCFG  = 0x38
+	REG_CLICKSRC  = 0x39
+	REG_CLICKTHS  = 0x3A
+	REG_TIMELIMIT = 0x3B
+	REG_TIMELATEN = 0x3C
+	REG_TIMEWINDO = 0x3D
+	REG_ACTTHS    = 0x3E
+	REG_ACTDUR    = 0x3F
+)
+
+type Range uint8
+
+const (
+	RANGE_16_G Range = 3 // +/- 16g
+	RANGE_8_G        = 2 // +/- 8g
+	RANGE_4_G        = 1 // +/- 4g
+	RANGE_2_G        = 0 // +/- 2g (default value)
+)
+
+type DataRate uint8
+
+// Data rate constants.
+const (
+	DATARATE_400_HZ         DataRate = 7 //  400Hz
+	DATARATE_200_HZ                  = 6 //  200Hz
+	DATARATE_100_HZ                  = 5 //  100Hz
+	DATARATE_50_HZ                   = 4 //   50Hz
+	DATARATE_25_HZ                   = 3 //   25Hz
+	DATARATE_10_HZ                   = 2 // 10 Hz
+	DATARATE_1_HZ                    = 1 // 1 Hz
+	DATARATE_POWERDOWN               = 0
+	DATARATE_LOWPOWER_1K6HZ          = 8
+	DATARATE_LOWPOWER_5KHZ           = 9
+)