[Issue #2] - adding code to verify a display is connected before attempting to use it

config.go.example

@@ -1,5 +1,9 @@
 package main
 
+import (
+	"time"
+)
+
 const (
 	WifiSSID = "My Wifi Name"
 	WifiPass = "SecretWifiPassword"
@@ -12,4 +16,6 @@ const (
 	NodeName = "Studio Weather"
 	NodeID   = "studio_env"
 	ClientID = "pico2w_studio_env"
+
+	UpdateInterval = 30 * time.Second
 )

go.mod

@@ -5,9 +5,12 @@ go 1.25.2
 require (
 	github.com/soypat/cyw43439 v0.1.1
 	github.com/soypat/lneto v0.3.2
+	tinygo.org/x/drivers v0.36.0
+	tinygo.org/x/tinyfont v0.7.0
 )
 
 require (
+	github.com/google/shlex v0.0.0-20191202100458-e7afc7fbc510 // indirect
 	github.com/soypat/seqs v0.0.0-20250124201400-0d65bc7c1710 // indirect
 	github.com/tinygo-org/pio v0.3.0 // indirect
 	golang.org/x/exp v0.0.0-20241204233417-43b7b7cde48d // indirect

go.sum

@@ -1,3 +1,5 @@
+github.com/google/shlex v0.0.0-20191202100458-e7afc7fbc510 h1:El6M4kTTCOh6aBiKaUGG7oYTSPP8MxqL4YI3kZKwcP4=
+github.com/google/shlex v0.0.0-20191202100458-e7afc7fbc510/go.mod h1:pupxD2MaaD3pAXIBCelhxNneeOaAeabZDe5s4K6zSpQ=
 github.com/soypat/cyw43439 v0.1.1 h1:vcaTiVzfuz3keK7lJpVxStZ6tV8HCw7Ugzsh1k4mneE=
 github.com/soypat/cyw43439 v0.1.1/go.mod h1:R2uSILRwSPmcmmKy5Z0FtK4ypgiPf5YqK+F+IKmXqxc=
 github.com/soypat/lneto v0.3.2 h1:iUFeRSq2czT7Db6MMOsAnMCBlKCqvIr941zsNf9dcu0=
@@ -8,3 +10,7 @@ github.com/tinygo-org/pio v0.3.0 h1:opEnOtw58KGB4RJD3/n/Rd0/djYGX3DeJiXLI6y/yDI=
 github.com/tinygo-org/pio v0.3.0/go.mod h1:wf6c6lKZp+pQOzKKcpzchmRuhiMc27ABRuo7KVnaMFU=
 golang.org/x/exp v0.0.0-20241204233417-43b7b7cde48d h1:0olWaB5pg3+oychR51GUVCEsGkeCU/2JxjBgIo4f3M0=
 golang.org/x/exp v0.0.0-20241204233417-43b7b7cde48d/go.mod h1:qj5a5QZpwLU2NLQudwIN5koi3beDhSAlJwa67PuM98c=
+tinygo.org/x/drivers v0.36.0 h1:F0x342A6GWqh6abtCa57uAxCyz/b9MbGzvIVvIf+gpE=
+tinygo.org/x/drivers v0.36.0/go.mod h1:DQgKyHkB4G6IEOKVTAjApbKnWGwESN91EVJO+nMOE9Y=
+tinygo.org/x/tinyfont v0.7.0 h1:Ju901eGRThlHLoti9K7myMYyv4phd3I0DrJwc14NTTU=
+tinygo.org/x/tinyfont v0.7.0/go.mod h1:onflMSkpWl7r7j4MIqhPEVV39pn7yL4N3MOePl3G+G8=

main.go

@@ -9,6 +9,11 @@ import (
 	"machine"
 	"strconv"
 	"time"
+	"image/color"
+
+	"tinygo.org/x/drivers/ssd1306"
+	"tinygo.org/x/tinyfont"
+	"tinygo.org/x/tinyfont/proggy"
 )
 
 var StateTopic = fmt.Sprintf("homeassistant/sensor/%s/state", NodeID)
@@ -292,10 +297,10 @@ func panicErr(msg string, err error) {
 func main() {
 	time.Sleep(2 * time.Second)
 
-	// Configure I2C (Pin 16 SDA, Pin 17 SCL -> I2C0)
+	// Bump frequency to 400kHz for snappy display flushes
 	i2c := machine.I2C0
 	err := i2c.Configure(machine.I2CConfig{
-		Frequency: 100 * machine.KHz,
+		Frequency: 400 * machine.KHz,
 		SDA:       machine.GPIO16,
 		SCL:       machine.GPIO17,
 	})
@@ -303,6 +308,31 @@ func main() {
 		panicErr("I2C configuration", err)
 	}
 
+	// Instantiate nil oled variable
+	var oled *ssd1306.Device
+	// White color for display
+	white := color.RGBA{R: 255, G: 255, B: 255, A: 255}
+
+	// Probe address 0x3C with a zero-byte or 1-byte read
+	var dummy [1]byte
+	if err := i2c.ReadRegister(0x3C, 0x00, dummy[:]); err == nil {
+	    println("SSD1306 detected at 0x3C")
+	    dev := ssd1306.NewI2C(i2c)
+	    dev.Configure(ssd1306.Config{
+	        Address: 0x3C,
+	        Width:   128,
+	        Height:  64,
+	    })
+	    oled = dev
+
+			// Run some initial clearing and add booting text to the screen
+			oled.ClearBuffer()
+			tinyfont.WriteLine(oled, &proggy.TinySZ8pt7b, 0, 16, "Booting...", white)
+			oled.Display()
+	} else {
+	    println("SSD1306 not found — running headless")
+	}
+
 	bme, err := NewBME280(i2c, BME280Addr)
 	if err != nil {
 		panicErr("BME280 init", err)
@@ -338,14 +368,25 @@ func main() {
 		if err != nil {
 			println("BME280 read error:", err.Error())
 		} else {
+			// Publish MQTT
 			stateJSON := fmt.Sprintf(`{"temperature":%.2f,"humidity":%.2f,"pressure":%.2f}`, t, h, p)
 			if err := mqtt.Publish(StateTopic, []byte(stateJSON), false); err != nil {
 				println("MQTT publish error:", err.Error())
 			} else {
 				println(fmt.Sprintf("[%s] Published: %s", NodeName, stateJSON))
 			}
+
+			// Render to OLED
+			if oled != nil {
+		    oled.ClearBuffer()
+		    tinyfont.WriteLine(oled, &proggy.TinySZ8pt7b, 0, 14, fmt.Sprintf("Node: %s", NodeName), white)
+		    tinyfont.WriteLine(oled, &proggy.TinySZ8pt7b, 0, 30, fmt.Sprintf("Temp: %.1f C", t), white)
+		    tinyfont.WriteLine(oled, &proggy.TinySZ8pt7b, 0, 46, fmt.Sprintf("Hum:  %.1f %%", h), white)
+		    tinyfont.WriteLine(oled, &proggy.TinySZ8pt7b, 0, 60, fmt.Sprintf("Pres: %.1f hPa", p), white)
+		    oled.Display()
+			}
 		}
 
-		time.Sleep(30 * time.Second)
+		time.Sleep(UpdateInterval)
 	}
 }