sensor: added driver for MCP9808 temperature sensor

samples/mcp9808.go

@@ -0,0 +1,119 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+
+	"github.com/kidoman/embd"
+	_ "github.com/kidoman/embd/host/rpi"
+	"github.com/kidoman/embd/sensor/mcp9808"
+)
+
+func main() {
+	bus := embd.NewI2CBus(1)
+	defer embd.CloseI2C()
+
+	therm, _ := mcp9808.New(bus)
+	// set sensor to low power mode when we're done
+	defer therm.SetShutdownMode(true)
+
+	if id, err := therm.ManufacturerID(); err == nil {
+		fmt.Printf("Manufacturer ID: 0x%x\n", id)
+	}
+
+	if devID, rev, err := therm.DeviceID(); err == nil {
+		fmt.Printf("Device ID: 0x%x rev. 0x%x\n", devID, rev)
+	}
+
+	therm.SetShutdownMode(false)
+	therm.SetCriticalTempLock(false)
+	therm.SetWindowTempLock(false)
+	therm.SetAlertMode(true)
+	therm.SetInterruptClear(true)
+	therm.SetAlertStatus(true)
+	therm.SetAlertControl(true)
+	therm.SetAlertSelect(false)
+	therm.SetAlertPolarity(true)
+
+	// get faster results (130ms vs 250ms default)
+	therm.SetTempResolution(mcp9808.EighthC)
+
+	config, _ := therm.Config()
+	fmt.Printf("New Config: %b\n", config)
+
+	if err := therm.SetCriticalTemp(TempFToC(95)); err != nil {
+		panic(err)
+	}
+	critTemp, err := therm.CriticalTemp()
+	if err != nil {
+		fmt.Printf("Error reading critical temp limit: %s\n", err.Error())
+	}
+	fmt.Printf("Critical Temp set to: %fC\n", critTemp)
+
+	if err := therm.SetWindowTempLower(TempFToC(60)); err != nil {
+		panic(err)
+	}
+	lowerTemp, err := therm.WindowTempLower()
+	if err != nil {
+		fmt.Printf("Error reading lower temp limit: %s\n", err.Error())
+	}
+	fmt.Printf("Lower Temp Limit set to: %fC\n", lowerTemp)
+
+	if err := therm.SetWindowTempUpper(TempFToC(80)); err != nil {
+		panic(err)
+	}
+	upperTemp, _ := therm.WindowTempUpper()
+	fmt.Printf("Upper Temp Limit set to: %fC\n", upperTemp)
+
+	therm.SetCriticalTempLock(true)
+	therm.SetWindowTempLock(true)
+
+	alert, err := embd.NewDigitalPin(23)
+	if err != nil {
+		panic(err)
+	}
+	defer alert.Close()
+
+	alert.SetDirection(embd.In)
+	alert.ActiveLow(false)
+
+	err = alert.Watch(embd.EdgeRising, func(alert embd.DigitalPin) {
+		fmt.Printf("Temperature is outside the specified window!\n")
+		therm.SetInterruptClear(true)
+		therm.Config()
+	})
+	if err != nil {
+		panic(err)
+	}
+
+	cancel := make(chan bool)
+	go func() {
+		reader := bufio.NewReader(os.Stdin)
+		reader.ReadString('\n')
+		cancel <- true
+	}()
+
+	for {
+		select {
+		case <-cancel:
+			return
+		default:
+			temp, err := therm.AmbientTemp()
+			if err != nil {
+				fmt.Printf("Error reading temp: %s\n", err.Error())
+			} else {
+				fmt.Printf("Current temp is: %fF (%fC), Window Alert: %v, Critical Alert: %v\n",
+					TempCToF(temp.CelsiusDeg), temp.CelsiusDeg, temp.AboveUpper || temp.BelowLower, temp.AboveCritical)
+			}
+		}
+	}
+}
+
+func TempCToF(tempC float64) float64 {
+	return tempC*9/5 + 32
+}
+
+func TempFToC(tempF float64) float64 {
+	return (tempF - 32) * 5 / 9
+}