Add support for LPS22HB MEMS nano pressure sensor (#297)

lps22hb: add support for lps22hb

Makefile

@@ -81,6 +81,8 @@ smoke-test:
 	@md5sum ./build/test.hex
 	tinygo build -size short -o ./build/test.hex -target=circuitplay-express ./examples/lis3dh/main.go
 	@md5sum ./build/test.hex
+	tinygo build -size short -o ./build/test.hex -target=nano-33-ble ./examples/lps22hb/main.go
+	@md5sum ./build/test.hex
 	tinygo build -size short -o ./build/test.hex -target=microbit ./examples/lsm303agr/main.go
 	@md5sum ./build/test.hex
 	tinygo build -size short -o ./build/test.hex -target=arduino-nano33 ./examples/lsm6ds3/main.go
@@ -214,7 +216,7 @@ DRIVERS = $(wildcard */)
 NOTESTS = build examples flash semihosting pcd8544 shiftregister st7789 microphone mcp3008 gps microbitmatrix \
 		hcsr04 ssd1331 ws2812 thermistor apa102 easystepper ssd1351 ili9341 wifinina shifter hub75 \
 		hd44780 buzzer ssd1306 espat l9110x st7735 bmi160 l293x dht keypad4x4 max72xx p1am tone tm1637 \
-		pcf8563 mcp2515 servo sdcard rtl8720dn image cmd i2csoft hts221
+		pcf8563 mcp2515 servo sdcard rtl8720dn image cmd i2csoft hts221 lps22hb
 TESTS = $(filter-out $(addsuffix /%,$(NOTESTS)),$(DRIVERS))
 
 unit-test:

examples/lps22hb/main.go

@@ -0,0 +1,37 @@
+package main
+
+import (
+	"machine"
+	"time"
+
+	"tinygo.org/x/drivers/lps22hb"
+)
+
+func main() {
+
+	machine.I2C1.Configure(machine.I2CConfig{
+		SCL:       machine.P0_15, // SCL1 on Nano 33 BLE Sense
+		SDA:       machine.P0_14, // SDA1 on Nano 33 BLE Sense
+		Frequency: machine.TWI_FREQ_400KHZ,
+	})
+
+	sensor := lps22hb.New(machine.I2C1)
+
+	if !sensor.Connected() {
+		println("LPS22HB not connected!")
+		return
+	}
+
+	sensor.Configure()
+
+	for {
+
+		p, _ := sensor.ReadPressure()
+		t, _ := sensor.ReadTemperature()
+		println("p =", float32(p)/1000.0, "hPa / t =", float32(t)/1000.0, "*C")
+		time.Sleep(time.Second)
+		// note: the device would power down itself after each query
+
+	}
+
+}

lps22hb/lps22hb.go

@@ -0,0 +1,73 @@
+// Package lps22hb implements a driver for LPS22HB, a MEMS nano pressure sensor.
+//
+// Datasheet: https://www.st.com/resource/en/datasheet/dm00140895.pdf
+//
+package lps22hb
+
+import (
+	"tinygo.org/x/drivers"
+)
+
+// Device wraps an I2C connection to a HTS221 device.
+type Device struct {
+	bus     drivers.I2C
+	Address uint8
+}
+
+// Connected returns whether LPS22HB has been found.
+// It does a "who am I" request and checks the response.
+func (d *Device) Connected() bool {
+	data := []byte{0}
+	d.bus.ReadRegister(d.Address, LPS22HB_WHO_AM_I_REG, data)
+	return data[0] == 0xB1
+}
+
+// Configure sets up the LPS22HB device for communication.
+func (d *Device) Configure() {
+	// set to block update mode
+	d.bus.WriteRegister(d.Address, LPS22HB_CTRL1_REG, []byte{0x02})
+}
+
+// ReadPressure returns the pressure in milli pascals (mPa).
+func (d *Device) ReadPressure() (pressure int32, err error) {
+	d.waitForOneShot()
+
+	// read data
+	data := []byte{0, 0, 0}
+	d.bus.ReadRegister(d.Address, LPS22HB_PRESS_OUT_REG, data[:1])
+	d.bus.ReadRegister(d.Address, LPS22HB_PRESS_OUT_REG+1, data[1:2])
+	d.bus.ReadRegister(d.Address, LPS22HB_PRESS_OUT_REG+2, data[2:])
+	pValue := float32(uint32(data[2])<<16|uint32(data[1])<<8|uint32(data[0])) / 4096.0
+
+	return int32(pValue * 1000), nil
+}
+
+// ReadTemperature returns the temperature in celsius milli degrees (°C/1000).
+func (d *Device) ReadTemperature() (temperature int32, err error) {
+	d.waitForOneShot()
+
+	// read data
+	data := []byte{0, 0}
+	d.bus.ReadRegister(d.Address, LPS22HB_TEMP_OUT_REG, data[:1])
+	d.bus.ReadRegister(d.Address, LPS22HB_TEMP_OUT_REG+1, data[1:])
+	tValue := float32(int16(uint16(data[1])<<8|uint16(data[0]))) / 100.0
+
+	return int32(tValue * 1000), nil
+}
+
+// private functions
+
+// wait and trigger one shot in block update
+func (d *Device) waitForOneShot() {
+	// trigger one shot
+	d.bus.WriteRegister(d.Address, LPS22HB_CTRL2_REG, []byte{0x01})
+
+	// wait until one shot is cleared
+	data := []byte{1}
+	for {
+		d.bus.ReadRegister(d.Address, LPS22HB_CTRL2_REG, data)
+		if data[0]&0x01 == 0 {
+			break
+		}
+	}
+}

lps22hb/lps22hb_generic.go

@@ -0,0 +1,14 @@
+//go:build !nano_33_ble
+// +build !nano_33_ble
+
+package lps22hb
+
+import "tinygo.org/x/drivers"
+
+// New creates a new LPS22HB connection. The I2C bus must already be
+// configured.
+//
+// This function only creates the Device object, it does not touch the device.
+func New(bus drivers.I2C) Device {
+	return Device{bus: bus, Address: LPS22HB_ADDRESS}
+}

lps22hb/lps22hb_nano_33_ble.go

@@ -0,0 +1,29 @@
+//go:build nano_33_ble
+// +build nano_33_ble
+
+package lps22hb
+
+import (
+	"machine"
+	"time"
+
+	"tinygo.org/x/drivers"
+)
+
+// New creates a new LPS22HB connection. The I2C bus must already be
+// configured.
+//
+// This function only creates the Device object, it does not touch the device.
+func New(bus drivers.I2C) Device {
+	// turn on internal power pin (machine.P0_22) and I2C1 pullups power pin (machine.P1_00)
+	// and wait a moment.
+	ENV := machine.P0_22
+	ENV.Configure(machine.PinConfig{Mode: machine.PinOutput})
+	ENV.High()
+	R := machine.P1_00
+	R.Configure(machine.PinConfig{Mode: machine.PinOutput})
+	R.High()
+	time.Sleep(time.Millisecond * 10)
+
+	return Device{bus: bus, Address: LPS22HB_ADDRESS}
+}

lps22hb/registers.go

@@ -0,0 +1,15 @@
+package lps22hb
+
+const (
+
+	// I2C address
+	LPS22HB_ADDRESS = 0x5C
+
+	// control/status registers
+	LPS22HB_WHO_AM_I_REG  = 0x0F
+	LPS22HB_CTRL1_REG     = 0x10
+	LPS22HB_CTRL2_REG     = 0x11
+	LPS22HB_STATUS_REG    = 0x27
+	LPS22HB_PRESS_OUT_REG = 0x28
+	LPS22HB_TEMP_OUT_REG  = 0x2B
+)