Initial working project

main.go

@@ -0,0 +1,161 @@
+package main
+
+import (
+  "fmt"
+  "machine"
+  "net/netip"
+  "time"
+  "image/color"
+
+  "tinygo.org/x/drivers/ssd1306"
+  "tinygo.org/x/tinyfont"
+  "tinygo.org/x/tinyfont/freesans"
+  "tinygo.org/x/tinyfont/proggy"
+)
+
+var (
+  defaultFont = &freesans.Regular9pt7b
+  tinyFont = &proggy.TinySZ8pt7b
+)
+
+// -------------------------------------------------------------
+// Panic Handler & Entry Point
+// -------------------------------------------------------------
+func panicErr(msg string, err error) {
+  if err != nil {
+    println("FATAL:", msg, "-", err.Error())
+  }
+  for {
+    time.Sleep(500 * time.Millisecond)
+  }
+}
+
+// syncNTP triggers an NTP request and polls until completed or timed out.
+func syncNTP(stack *NetworkStack, server netip.Addr, timeout time.Duration) (time.Duration, error) {
+  if err := stack.stack.StartNTP(server); err != nil {
+    return 0, fmt.Errorf("start NTP: %w", err)
+  }
+
+  deadline := time.Now().Add(timeout)
+  for time.Now().Before(deadline) {
+    offset, done := stack.stack.ResultNTPOffset()
+    if done {
+      return offset, nil
+    }
+    time.Sleep(50 * time.Millisecond)
+  }
+
+  return 0, fmt.Errorf("NTP request timed out")
+}
+
+func main() {
+  time.Sleep(2 * time.Second)
+  println("Starting app...")
+
+  // Bump frequency to 400kHz for snappy display flushes
+  i2c := machine.I2C0
+  err := i2c.Configure(machine.I2CConfig{
+    Frequency: 400 * machine.KHz,
+    SDA:       machine.GPIO4,
+    SCL:       machine.GPIO5,
+  })
+  if err != nil {
+    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
+  println("Initializing display...")
+  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, defaultFont, 0, 32, "Booting...", white)
+      oled.Display()
+      time.Sleep(1 * time.Second)
+  } else {
+      panicErr("Failed to init display.", err)
+  }
+
+  println("Starting Wi-Fi...")
+  oled.ClearBuffer()
+  tinyfont.WriteLine(oled, defaultFont, 0, 32, "Starting Wi-Fi...", white)
+  oled.Display()
+
+  netStack, err := InitNetwork(WifiSSID, WifiPass)
+  if err != nil {
+    panicErr("network init", err)
+  }
+
+  println("Wi-Fi Connected!")
+  oled.ClearBuffer()
+  tinyfont.WriteLine(oled, defaultFont, 0, 32, "Wi-Fi Connected!", white)
+  oled.Display()
+  time.Sleep(1 * time.Second)
+
+  // Extract IP string from the returned NetworkStack
+  ipStr := netStack.localIP.String()
+
+  // Sync wall time using public NTP (e.g. Cloudflare: 162.159.200.1 / time.cloudflare.com)
+  println("Synchronizing clock via NTP...")
+  oled.ClearBuffer()
+  tinyfont.WriteLine(oled, defaultFont, 0, 32, "Syncing NTP...", white)
+  oled.Display()
+  ntpServer := netip.MustParseAddr("162.159.200.1")
+  timeOffset, err := syncNTP(netStack, ntpServer, 5*time.Second)
+  if err != nil {
+    panicErr("NTP sync failed", err)
+  }
+
+  println("NTP synced successfully!")
+  oled.ClearBuffer()
+  tinyfont.WriteLine(oled, defaultFont, 0, 32, "NTP synced!", white)
+  oled.Display()
+  time.Sleep(1 * time.Second)
+
+  lastSecond := -1
+
+  for {
+    currentTime := time.Now().Add(timeOffset).UTC()
+    currentSecond := currentTime.Second()
+
+    // Skip display refreshes if the second hasn't changed to save the i2c bus
+    if currentSecond != lastSecond {
+      lastSecond = currentSecond
+
+      // Alternate colon (:) with space ( ) every second
+      timeSeperator := ":"
+      if currentSecond % 2 == 1 {
+        timeSeperator = " "
+      }
+
+      // Create the awful time string before displaying it
+      timeStr := fmt.Sprintf("%02d%s%02d%s%02d UTC",
+        currentTime.Hour(), timeSeperator,
+        currentTime.Minute(), timeSeperator,
+        currentTime.Second())
+
+      oled.ClearBuffer()
+      // Time
+      tinyfont.WriteLine(oled, defaultFont, 8, 32, timeStr, white)
+      // IP Address
+      tinyfont.WriteLine(oled, tinyFont, 0, 60, fmt.Sprintf("IP: %s", ipStr), white)
+      oled.Display()
+    }
+
+    time.Sleep(10 * time.Millisecond)
+  }
+}