rp2040: rtc delayed interrupt

src/examples/rtcinterrupt/rtcinterrupt.go

@@ -0,0 +1,35 @@
+//go:build rp2040
+
+package main
+
+// This example demonstrates scheduling a delayed interrupt by real time clock.
+//
+// An interrupt may execute user callback function or used for its side effects
+// like waking up from sleep or dormant states.
+//
+// The interrupt can be configured to repeat.
+//
+// There is no separate method to disable interrupt, use 0 delay for that.
+//
+// Unfortunately, it is not possible to use time.Duration to work with RTC directly,
+// that would introduce a circular dependency between "machine" and "time" packages.
+
+import (
+	"fmt"
+	"machine"
+	"time"
+)
+
+func main() {
+
+	// Schedule and enable recurring interrupt.
+	// The callback function is executed in the context of an interrupt handler,
+	// so regular restructions for this sort of code apply: no blocking, no memory allocation, etc.
+	delay := time.Minute + 12*time.Second
+	machine.RTC.SetInterrupt(uint32(delay.Seconds()), true, func() { println("Peekaboo!") })
+
+	for {
+		fmt.Printf("%v\r\n", time.Now().Format(time.RFC3339))
+		time.Sleep(1 * time.Second)
+	}
+}