Reset 1-wire bus when temperature readings fail 60 consecutive times

cmd/fermentord/loop.go

@@ -2,7 +2,6 @@ package main
 
 import (
 	"context"
-	"encoding/json"
 	"log"
 	"sync"
 	"time"
@@ -68,6 +67,11 @@ func mainLoop(ctx context.Context, wg *sync.WaitGroup, js nats.JetStream, config
 	go temperature.PollSensors(ctx, wg, 1*time.Second, config.Sensors.Weight)
 	go tilt.PollSensors(ctx, wg, 1*time.Minute, 20*time.Second)
 
+	oneWirePowerUpChannel := make(chan bool)
+	oneWirePowerUpTimer := time.AfterFunc(1*time.Millisecond, func() {
+		oneWirePowerUpChannel <- true
+	})
+
 	for {
 		select {
 		case reading := <-temperature.Reading:
@@ -75,6 +79,25 @@ func mainLoop(ctx context.Context, wg *sync.WaitGroup, js nats.JetStream, config
 			ingest.AddReading(reading)
 			//display.SetTemperature(reading)
 
+		case <-temperature.RequestReset:
+			log.Print("Powering down one wire bus for 20 seconds")
+			gpio.StopOneWirePower()
+			oneWirePowerUpTimer.Reset(20 * time.Second)
+
+			// Publish to NATS
+			e := dwingest.Event{
+				Time:  time.Now().UTC(),
+				Event: "ONEWIRE_RESET",
+			}
+			if err := ingest.Publish(config.NATS.Subject.Event, js, e); err != nil {
+				hub.CaptureException(err)
+				log.Print(err)
+			}
+
+		case <-oneWirePowerUpChannel:
+			log.Print("Powering up one wire bus")
+			gpio.StartOneWirePower()
+
 		case ev := <-gpio.C:
 			var evs string
 
@@ -96,19 +119,12 @@ func mainLoop(ctx context.Context, wg *sync.WaitGroup, js nats.JetStream, config
 				evs = "DOOR_OPENED"
 			}
 
-			b, err := json.Marshal(map[string]interface{}{
-				"time":  time.Now().UTC(),
-				"event": evs,
-			})
-			if err != nil {
-				hub.CaptureException(err)
-				log.Printf("Error marshaling JSON: %v", err)
-				break
-			}
-
 			// Publish to NATS
-			_, err = js.Publish(config.NATS.Subject.Event, b, nats.AckWait(1*time.Second))
-			if err != nil {
+			e := dwingest.Event{
+				Time:  time.Now().UTC(),
+				Event: evs,
+			}
+			if err := ingest.Publish(config.NATS.Subject.Event, js, e); err != nil {
 				hub.CaptureException(err)
 				log.Print(err)
 			}

internal/dwingest/nats.go

@@ -64,16 +64,16 @@ func (p *DWIngest) Run(ctx context.Context, wg *sync.WaitGroup, js nats.JetStrea
 	for {
 		select {
 		case reading := <-p.chTemperatureReading:
-			p.publish(config.NATS.Subject.Temp, js, reading)
+			p.Publish(config.NATS.Subject.Temp, js, reading)
 
 		case state := <-p.chState:
-			p.publish(config.NATS.Subject.State, js, State{
+			p.Publish(config.NATS.Subject.State, js, State{
 				Time:  time.Now().UTC(),
 				State: controllers.ChamberStateMap[state],
 			})
 
 		case t := <-tilt.C:
-			p.publish(config.NATS.Subject.Tilt, js, Tilt{
+			p.Publish(config.NATS.Subject.Tilt, js, Tilt{
 				Time:        time.Now().UTC(),
 				Color:       string(t.Color()),
 				Gravity:     t.Gravity(),
@@ -86,7 +86,7 @@ func (p *DWIngest) Run(ctx context.Context, wg *sync.WaitGroup, js nats.JetStrea
 	}
 }
 
-func (p *DWIngest) publish(subject string, js nats.JetStream, reading any) error {
+func (p *DWIngest) Publish(subject string, js nats.JetStream, reading any) error {
 	b, err := json.Marshal(reading)
 	if err != nil {
 		p.hub.CaptureException(err)

internal/dwingest/types.go

@@ -13,3 +13,8 @@ type Tilt struct {
 	Gravity     float64   `json:"gravity"`
 	Temperature float64   `json:"temperature"`
 }
+
+type Event struct {
+	Time  time.Time `json:"time"`
+	Event string    `json:"event"`
+}

internal/hw/gpio.go

@@ -13,6 +13,10 @@ const (
 	pinHeaterPower = 24
 	pinLightsPower = 25
 
+	// GPIO21 is located at pin 13 on RPi 1B rev 1. Rev 2 and never boards
+	// has GPIO27 here.
+	pinOneWirePower = 21
+
 	off = 0
 	on  = 1
 )
@@ -28,6 +32,7 @@ const (
 type Gpio struct {
 	chip         *gpiod.Chip
 	doorOpen     *gpiod.Line
+	oneWirePower *gpiod.Line
 	lightsPower  *gpiod.Line
 	fanPower     *gpiod.Line
 	coolerPower  *gpiod.Line
@@ -71,6 +76,11 @@ func NewGpio() (*Gpio, error) {
 		p.C <- DoorClosed
 	}
 
+	p.oneWirePower, err = p.chip.RequestLine(pinOneWirePower, gpiod.AsOutput(0))
+	if err != nil {
+		return nil, err
+	}
+
 	p.lightsPower, err = p.chip.RequestLine(pinLightsPower, gpiod.AsOutput(0))
 	if err != nil {
 		return nil, err
@@ -99,7 +109,9 @@ func (p *Gpio) Close() {
 	p.heaterPower.SetValue(off)
 	p.fanPower.SetValue(off)
 	p.lightsPower.SetValue(off)
+	p.oneWirePower.SetValue(off)
 
+	p.oneWirePower.Close()
 	p.heaterPower.Close()
 	p.coolerPower.Close()
 	p.fanPower.Close()
@@ -142,6 +154,16 @@ func (p *Gpio) LightsOff() {
 	p.lightsPower.SetValue(off)
 }
 
+func (p *Gpio) StartOneWirePower() {
+	// Inverted logic due to PNP transistor switch
+	p.oneWirePower.SetValue(off)
+}
+
+func (p *Gpio) StopOneWirePower() {
+	// Inverted logic due to PNP transistor switch
+	p.oneWirePower.SetValue(on)
+}
+
 func (p *Gpio) onDoorStateChanged(le gpiod.LineEvent) {
 	switch le.Type {
 	case gpiod.LineEventFallingEdge:

pkg/temperature/ds18b20.go

@@ -42,6 +42,7 @@ var (
 	// Reading receives the temperature readings
 	Reading      chan TemperatureReading
 	ConfigUpdate chan configuration.Configuration
+	RequestReset chan bool
 
 	accErrTrigger int
 	sensors       []Sensor
@@ -50,6 +51,7 @@ var (
 func init() {
 	Reading = make(chan TemperatureReading, 30)
 	ConfigUpdate = make(chan configuration.Configuration, 1)
+	RequestReset = make(chan bool)
 	sensors = make([]Sensor, 0)
 }
 
@@ -75,7 +77,6 @@ func PollSensors(ctx context.Context, wg *sync.WaitGroup, readingInterval time.D
 	defer ticker.Stop()
 
 	for {
-	work_loop:
 		select {
 		case <-ticker.C:
 		poll_bus:
@@ -100,7 +101,7 @@ func PollSensors(ctx context.Context, wg *sync.WaitGroup, readingInterval time.D
 					accErrTrigger++
 					hub.CaptureException(err)
 					log.Print(err)
-					break work_loop
+					break
 				}
 
 				accErrTrigger = 0
@@ -119,8 +120,17 @@ func PollSensors(ctx context.Context, wg *sync.WaitGroup, readingInterval time.D
 			}
 
 			if accErrTrigger > 60 {
+				select {
+				case RequestReset <- true:
+					log.Print("Thermal bulk read failed 60 times in a row -- bus reset")
+
+					// Reset counter to allow 60 more reads
+					accErrTrigger = 0
+
+				default:
 					log.Fatal("Thermal bulk read failed 60 times in a row -- terminating")
 				}
+			}
 
 		case c := <-ConfigUpdate:
 			configure(c)