beginnings of the servo

pi/roverd/cmd/servoverifier/main.go

@@ -0,0 +1,95 @@
+package main
+
+import (
+	"flag"
+	"log"
+	"time"
+
+	rpio "github.com/stianeikeland/go-rpio/v4"
+)
+
+func main() {
+	var (
+		pinNum    = flag.Int("pin", 19, "BCM pin connected to the servo signal line")
+		freqHz    = flag.Int("freq", 50, "Servo PWM frequency in Hz")
+		cycleLen  = flag.Int("cycle", 20000, "PWM cycle length (counts per period)")
+		minPulse  = flag.Int("min", 900, "Minimum pulse width in microseconds")
+		maxPulse  = flag.Int("max", 2100, "Maximum pulse width in microseconds")
+		stepPulse = flag.Int("step", 100, "Pulse width increment in microseconds when sweeping")
+		sweeps    = flag.Int("sweeps", 2, "How many full min→max→min sweeps to perform")
+		pause     = flag.Duration("pause", 150*time.Millisecond, "Delay between pulse adjustments")
+		holdPulse = flag.Int("hold", 0, "Pulse width to hold before exiting (0 = midpoint of min/max)")
+	)
+	flag.Parse()
+
+	if *freqHz <= 0 || *cycleLen <= 0 {
+		log.Fatalf("invalid freq (%d) or cycle (%d)", *freqHz, *cycleLen)
+	}
+	if *minPulse <= 0 || *maxPulse <= 0 || *minPulse >= *maxPulse {
+		log.Fatalf("invalid min/max pulses (%d/%d)", *minPulse, *maxPulse)
+	}
+	if *stepPulse <= 0 {
+		log.Fatalf("step must be > 0 (got %d)", *stepPulse)
+	}
+	if *pause <= 0 {
+		log.Fatalf("pause must be > 0 (got %s)", pause)
+	}
+	if *sweeps < 0 {
+		log.Fatalf("sweeps must be >= 0 (got %d)", *sweeps)
+	}
+
+	if err := rpio.Open(); err != nil {
+		log.Fatalf("open gpio: %v", err)
+	}
+	defer rpio.Close()
+
+	pin := rpio.Pin(*pinNum)
+	pin.Mode(rpio.Pwm)
+
+	targetClock := *freqHz * *cycleLen
+	pin.Freq(targetClock)
+	log.Printf("Configured PWM pin %d at %d Hz (clock=%d Hz, cycle=%d)", *pinNum, *freqHz, targetClock, *cycleLen)
+
+	setPulse := func(us int) {
+		clamped := clamp(us, *minPulse, *maxPulse)
+		pin.DutyCycle(uint32(clamped), uint32(*cycleLen))
+		log.Printf("pulse -> %dµs", clamped)
+	}
+
+	mid := (*minPulse + *maxPulse) / 2
+	setPulse(mid)
+
+	runSweep := func() {
+		for pulse := *minPulse; pulse <= *maxPulse; pulse += *stepPulse {
+			setPulse(pulse)
+			time.Sleep(*pause)
+		}
+		for pulse := *maxPulse - *stepPulse; pulse >= *minPulse; pulse -= *stepPulse {
+			setPulse(pulse)
+			time.Sleep(*pause)
+		}
+	}
+
+	for i := 0; i < *sweeps; i++ {
+		log.Printf("Sweep %d/%d", i+1, *sweeps)
+		runSweep()
+	}
+
+	finalPulse := *holdPulse
+	if finalPulse <= 0 {
+		finalPulse = mid
+	}
+	setPulse(finalPulse)
+	log.Printf("Holding at %dµs", clamp(finalPulse, *minPulse, *maxPulse))
+	log.Print("Servo verification complete")
+}
+
+func clamp(value, min, max int) int {
+	if value < min {
+		return min
+	}
+	if value > max {
+		return max
+	}
+	return value
+}

pi/roverd/go.mod

@@ -3,6 +3,7 @@ module multiroombarover/pi/roverd
 go 1.25.4
 
 require (
+	github.com/stianeikeland/go-rpio/v4 v4.6.0
 	github.com/tarm/serial v0.0.0-20180830185346-98f6abe2eb07
 	github.com/warthog618/go-gpiocdev v0.9.1
 	gopkg.in/yaml.v3 v3.0.1

pi/roverd/go.sum

@@ -4,6 +4,8 @@ github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
 github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stianeikeland/go-rpio/v4 v4.6.0 h1:eAJgtw3jTtvn/CqwbC82ntcS+dtzUTgo5qlZKe677EY=
+github.com/stianeikeland/go-rpio/v4 v4.6.0/go.mod h1:A3GvHxC1Om5zaId+HqB3HKqx4K/AqeckxB7qRjxMK7o=
 github.com/stretchr/testify v1.9.0 h1:HtqpIVDClZ4nwg75+f6Lvsy/wHu+3BoSGCbBAcpTsTg=
 github.com/stretchr/testify v1.9.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
 github.com/tarm/serial v0.0.0-20180830185346-98f6abe2eb07 h1:UyzmZLoiDWMRywV4DUYb9Fbt8uiOSooupjTq10vpvnU=