feat(machine/stm32): add STM32H7 and NUCLEO-H753ZI support

src/examples/pwm/nucleo-h753zi.go

@@ -0,0 +1,11 @@
+//go:build stm32h7
+
+package main
+
+import "machine"
+
+var (
+	pwm  = &machine.TIM1
+	pinA = machine.PA8
+	pinB = machine.PA9
+)

src/examples/wwdg/main.go

@@ -0,0 +1,31 @@
+package main
+
+import (
+	"machine"
+	"time"
+)
+
+func main() {
+	time.Sleep(2 * time.Second)
+
+	println("configuring window watchdog")
+	config := machine.WindowWatchdogConfig{
+		TimeoutMicros: 100000, // 100ms
+		WindowPercent: 50,     // 50ms to 100ms refresh window
+	}
+
+	machine.WindowWatchdog.Configure(config)
+	machine.WindowWatchdog.Start()
+
+	println("updating wwdg for 1 second")
+	for i := 0; i < 10; i++ {
+		time.Sleep(75 * time.Millisecond) // middle of the window
+		machine.WindowWatchdog.Update()
+		println("alive")
+	}
+
+	println("entering tight loop (will reset)")
+	for {
+		time.Sleep(10 * time.Millisecond)
+	}
+}