NPA-700 sensor support - requires https://github.com/kidoman/embd/pull/37

samples/npa700b001d.go

@@ -0,0 +1,35 @@
+// +build ignore
+
+package main
+
+import (
+	"flag"
+	"fmt"
+
+	"github.com/zlowred/embd"
+	"github.com/zlowred/embd/sensor/npa700"
+
+	_ "github.com/zlowred/embd/host/all"
+)
+
+func main() {
+	flag.Parse()
+
+	if err := embd.InitI2C(); err != nil {
+		panic(err)
+	}
+	defer embd.CloseI2C()
+
+	bus := embd.NewI2CBus(1)
+
+	sensor := npa700.New(bus)
+
+	err := sensor.Read()
+	if err != nil {
+		panic(err)
+	}
+
+	fmt.Printf("Temp is %fC\n", sensor.Celsius())
+	fmt.Printf("Temp is %fF\n", sensor.Fahrenheit())
+	fmt.Printf("Pres is %fPa\n", sensor.Pascals(0, 1638, 14745, -6894.76, 6894.76))
+}

sensor/npa700/npa700.go

@@ -0,0 +1,50 @@
+// Package npa700 allows interfacing with GE NPA-700 pressure sensor. This sensor
+// has the ability to provide compensated temperature and pressure readings.
+package npa700
+
+import (
+	"github.com/zlowred/embd"
+	"sync"
+)
+
+// NPA700 represents a Bosch BMP180 barometric sensor.
+type NPA700 struct {
+	Bus  embd.I2CBus
+
+	RawTemperature int16
+	RawPressure int16
+	mu sync.Mutex
+}
+
+// New returns a handle to a BMP180 sensor.
+func New(bus embd.I2CBus) *NPA700 {
+	return &NPA700{Bus: bus}
+}
+
+func (sensor *NPA700) Read() error {
+	sensor.mu.Lock()
+	defer sensor.mu.Unlock()
+
+	data, err := sensor.Bus.ReadBytes(0x28, 4)
+
+	if err != nil {
+		return err
+	}
+
+	sensor.RawPressure = (int16(data[0]) << 8) + int16(data[1])
+	sensor.RawTemperature = (int16(data[2]) << 3) + (int16(data[3]) >> 5)
+
+	return nil
+}
+
+func (sensor *NPA700) Celsius() float32 {
+	return float32(sensor.RawTemperature) * 200. / 2048. - 50.
+}
+
+func (sensor *NPA700) Fahrenheit() float32 {
+	return (float32(sensor.RawTemperature) * 200. / 2048. - 50.) * 1.8 + 32.
+}
+
+func (sensor *NPA700) Pascals(offset float32, minValue float32, maxValue float32, minPressure float32, maxPressure float32) float32 {
+	return minPressure + (float32(sensor.RawPressure) + offset - minValue) / (maxValue - minValue) * (maxPressure - minPressure)
+}