From 18fb4bad6d8714e4b8222d0ce6ba992dccb7d796 Mon Sep 17 00:00:00 2001
From: Mike Shoup <mike@shoup.io>
Date: Fri, 28 Sep 2018 15:26:27 -0600
Subject: [PATCH] Basic thermostat stuff

---
 config.go |  4 ++--
 main.go   | 15 +++++++++---
 run.go    | 68 +++++++++++++++++++++++++++++++++++++++++++++++++++----
 3 files changed, 77 insertions(+), 10 deletions(-)

diff --git a/config.go b/config.go
index 362583f..6264dc0 100644
--- a/config.go
+++ b/config.go
@@ -14,10 +14,10 @@ type Sensor struct {
 	LowTemp     float64 `yaml:"lowtemp"`
 	HeatGPIO    int32   `yaml:"heatgpio"`
 	HeatPullup  bool    `yaml:"heatpullup"`
-	HeatMinutes int32   `yaml:"heatminutes"`
+	HeatMinutes float64 `yaml:"heatminutes"`
 	CoolGPIO    int32   `yaml:"coolgpio"`
 	CoolPullup  bool    `yaml:"coolpullup"`
-	CoolMinutes int32   `yaml:"coolminutes"`
+	CoolMinutes float64 `yaml:"coolminutes"`
 }
 
 // Config contains the applications configuration
diff --git a/main.go b/main.go
index 705f06a..7f36efa 100644
--- a/main.go
+++ b/main.go
@@ -4,7 +4,8 @@ import (
 	"log"
 	"sync"
 
-	arg "github.com/alexflint/go-arg"
+	"github.com/alexflint/go-arg"
+	"github.com/stianeikeland/go-rpio"
 )
 
 func main() {
@@ -23,12 +24,20 @@ func main() {
 		log.Fatal(err)
 	}
 
-	var wg sync.WaitGroup
+	// Prep for GPIO access
+	err = rpio.Open()
+	if err != nil {
+		log.Fatal(err)
+	}
 
+	// Launch the thermostat go routines
+	var wg sync.WaitGroup
 	for _, sensor := range config.Sensors {
 		wg.Add(1)
 		go RunThermostat(sensor)
 	}
-
 	wg.Wait()
+
+	// Close the GPIO access
+	rpio.Close()
 }
diff --git a/run.go b/run.go
index 6506309..2f31436 100644
--- a/run.go
+++ b/run.go
@@ -5,15 +5,16 @@ import (
 	"log"
 	"time"
 
+	"github.com/stianeikeland/go-rpio"
 	"github.com/yryz/ds18b20"
 )
 
 // State represents the current state of the thermostat
 type State struct {
-	Temp     float64
-	Cooling  bool
-	Heating  bool
-	Duration time.Duration
+	Temp    float64
+	Cooling bool
+	Heating bool
+	Changed time.Time
 }
 
 // ReadTemperature will return the current temperature (in degrees celsius) of a specific sensor.
@@ -33,9 +34,42 @@ func ReadTemperature(id string) (float64, error) {
 	return 0.0, errors.New("Sensor not found")
 }
 
+// SetPinState is used to turn a pin on or off.
+// If pullup is true, the pin will be pulled up when turned on, and pulled down when turned off.
+func SetPinState(pin rpio.Pin, on bool, pullup bool) {
+	switch {
+	case on && pullup:
+		pin.PullUp()
+	case on && !pullup:
+		pin.PullDown()
+	case !on && !pullup:
+		pin.PullUp()
+	default:
+		pin.PullDown()
+	}
+}
+
+// GetPinState will return true if the pin is on.
+// If pullup is true, the pin will be on when pulled up.
+func GetPinState(pin rpio.Pin, pullup bool) bool {
+	switch pin.Read() {
+	case rpio.High:
+		return pullup
+	default:
+		return !pullup
+	}
+}
+
 // RunThermostat monitors the temperature of the supplied sensor and does its best to keep it at the desired state.
 func RunThermostat(sensor Sensor) {
 	var s State
+	s.Changed = time.Now()
+
+	cpin := rpio.Pin(sensor.CoolGPIO)
+	cpin.Output()
+
+	hpin := rpio.Pin(sensor.HeatGPIO)
+	hpin.Output()
 
 	for {
 		t, err := ReadTemperature(sensor.ID)
@@ -43,7 +77,31 @@ func RunThermostat(sensor Sensor) {
 			log.Panicln(err)
 		}
 
+		min := time.Since(s.Changed).Minutes()
+
+		switch {
+		case t > sensor.HighTemp && t < sensor.HighTemp:
+			log.Panic("Invalid state! Temperature is too high AND too low!")
+		case t > sensor.HighTemp && GetPinState(hpin, sensor.HeatPullup):
+			SetPinState(hpin, false, sensor.HeatPullup)
+		case t > sensor.HighTemp && min > sensor.CoolMinutes:
+			SetPinState(cpin, true, sensor.CoolPullup)
+		case t > sensor.HighTemp:
+			break
+		case t < sensor.LowTemp && GetPinState(cpin, sensor.CoolPullup):
+			SetPinState(cpin, false, sensor.CoolPullup)
+		case t < sensor.LowTemp && min > sensor.HeatMinutes:
+			SetPinState(hpin, true, sensor.HeatPullup)
+		case t < sensor.LowTemp:
+			break
+		default: // Turn off both switches
+			SetPinState(cpin, false, sensor.CoolPullup)
+			SetPinState(hpin, false, sensor.HeatPullup)
+		}
+
 		s.Temp = t
-		log.Printf("Temp: %.2f, Cooling: %t, Heating: %t Duration: %d", s.Temp, s.Cooling, s.Heating, s.Duration)
+		s.Cooling = GetPinState(cpin, sensor.CoolPullup)
+		s.Heating = GetPinState(hpin, sensor.HeatPullup)
+		log.Printf("Temp: %.2f, Cooling: %t, Heating: %t, Changed: %s", s.Temp, s.Cooling, s.Heating, s.Changed)
 	}
 }