update BRC pulse handling

README.md

@@ -43,4 +43,4 @@ sudo ./pi/install_roverd.sh --mediamtx
 
 Then point each rover's `/etc/roverd.yaml` at `ws://<server>:8080/rover`, enable the sensor stream from the UI, and drive with WASD.
 Use the “Restart Camera” button if you enable media management so roverd can bounce the mediamtx service remotely.
-Heads-up: the BRC pulser currently hits `/sys/class/gpio/export`, so the service needs root privileges on Raspberry Pi OS. Until it’s switched to `libgpiod`, set `brc.gpioPin: -1` if you prefer to run unprivileged (the Create will then nap unless something else keeps it awake).
+Heads-up: the BRC pulser now uses libgpiod; make sure the `roverd` service account is in the `gpio` group (or otherwise allowed to access `/dev/gpiochip*`) and set `brc.gpioChip` if your hardware exposes a different chip name.

docs/pi-deployment.md

@@ -62,9 +62,9 @@ If the script installs the sample config, it will remind you to edit `/etc/rover
    sudo systemctl enable --now roverd.service
    ```
 
-`roverd` requires access to `/dev/ttyAMA0` and `/sys/class/gpio`; keeping it under its own user ensures the rest of the system stays isolated.  
+`roverd` requires access to `/dev/ttyAMA0` and `/dev/gpiochip*`; keeping it under its own user ensures the rest of the system stays isolated—just make sure the account belongs to the `dialout` and `gpio` groups so it can reach the UART and libgpiod.  
-`mediamtx` needs read access to the camera devices (`/dev/media*`, `/dev/video*`), so the install script adds its service account to the `video` group; if you created the user manually, make sure it belongs to `video`.
+`mediamtx` needs read access to the camera devices (`/dev/media*`, `/dev/video*`), so the install script adds its service account to the `video` group; if you created the user manually, make sure it belongs to `video`.  
-**BRC note:** writing to `/sys/class/gpio/export` typically requires root on Raspberry Pi OS. Until the pulser moves to `libgpiod`, either run the service as root or set `brc.gpioPin: -1` (rover may eventually sleep).  
+**BRC note:** configure `brc.gpioPin` (and `brc.gpioChip` if you’re not using `gpiochip0`) and ensure the `roverd` user has permission to toggle that line—no root privileges are required anymore.  
 If you set `media.manage: true` in `/etc/roverd.yaml`, make sure the `roverd` service account can invoke `systemctl <action> <media.service>` (either run the unit as root or grant sudo privileges for that command).
 
 ## Configuring mediaMTX

pi/roverd/brc.go

@@ -2,36 +2,42 @@ package roverd
 
 import (
 	"context"
-	"fmt"
 	"log"
-	"os"
-	"path/filepath"
-	"strconv"
 	"time"
+
+	gpiocdev "github.com/warthog618/go-gpiocdev"
 )
 
 type BRCPulser struct {
 	cfg    BRCConfig
 	logger *log.Logger
+	line   *gpiocdev.Line
 }
 
 func NewBRCPulser(cfg BRCConfig, logger *log.Logger) (*BRCPulser, error) {
-	if err := exportGPIO(cfg.GPIOPin); err != nil {
+	chip := cfg.GPIOChip
-		return nil, err
+	if chip == "" {
+		chip = "gpiochip0"
 	}
-	if err := writeGPIO(cfg.GPIOPin, "direction", []byte("out\n")); err != nil {
+
-		return nil, err
+	line, err := gpiocdev.RequestLine(
-	}
+		chip,
-	if err := writeGPIO(cfg.GPIOPin, "value", []byte("1\n")); err != nil {
+		cfg.GPIOPin,
+		gpiocdev.AsOutput(1),
+		gpiocdev.WithConsumer("roverd-brc"),
+	)
+	if err != nil {
 		return nil, err
 	}
 
-	return &BRCPulser{cfg: cfg, logger: logger}, nil
+	return &BRCPulser{cfg: cfg, logger: logger, line: line}, nil
 }
 
 func (b *BRCPulser) Close() {
-	_ = writeGPIO(b.cfg.GPIOPin, "value", []byte("1\n"))
+	if b.line != nil {
-	_ = unexportGPIO(b.cfg.GPIOPin)
+		_ = b.line.SetValue(1)
+		b.line.Close()
+	}
 }
 
 func (b *BRCPulser) Start(ctx context.Context) {
@@ -51,33 +57,15 @@ func (b *BRCPulser) Start(ctx context.Context) {
 }
 
 func (b *BRCPulser) pulseOnce() {
-	if err := writeGPIO(b.cfg.GPIOPin, "value", []byte("0\n")); err != nil {
+	if b.line == nil {
+		return
+	}
+	if err := b.line.SetValue(0); err != nil {
 		b.logger.Printf("brc pulse low: %v", err)
 		return
 	}
 	time.Sleep(b.cfg.PulseWidth.Duration)
-	if err := writeGPIO(b.cfg.GPIOPin, "value", []byte("1\n")); err != nil {
+	if err := b.line.SetValue(1); err != nil {
 		b.logger.Printf("brc pulse high: %v", err)
 	}
 }
-
-func exportGPIO(pin int) error {
-	err := os.WriteFile("/sys/class/gpio/export", []byte(strconv.Itoa(pin)), 0o644)
-	if err != nil && !os.IsExist(err) {
-		return err
-	}
-	return nil
-}
-
-func unexportGPIO(pin int) error {
-	err := os.WriteFile("/sys/class/gpio/unexport", []byte(strconv.Itoa(pin)), 0o644)
-	if err != nil && !os.IsNotExist(err) {
-		return err
-	}
-	return nil
-}
-
-func writeGPIO(pin int, field string, data []byte) error {
-	path := filepath.Join("/sys/class/gpio", fmt.Sprintf("gpio%d", pin), field)
-	return os.WriteFile(path, data, 0o644)
-}

pi/roverd/config.go

@@ -37,6 +37,7 @@ func (d Duration) MarshalYAML() (interface{}, error) {
 
 type BRCConfig struct {
 	GPIOPin    int      `yaml:"gpioPin"`
+	GPIOChip   string   `yaml:"gpioChip"`
 	PulseEvery Duration `yaml:"pulseEvery"`
 	PulseWidth Duration `yaml:"pulseWidth"`
 }
@@ -78,7 +79,8 @@ func LoadConfig(path string) (*Config, error) {
 	cfg := Config{
 		MaxWheelMMs: 500,
 		BRC: BRCConfig{
-			GPIOPin: -1,
+			GPIOPin:  -1,
+			GPIOChip: "gpiochip0",
 			PulseEvery: Duration{
 				Duration: time.Minute,
 			},
@@ -108,6 +110,9 @@ func LoadConfig(path string) (*Config, error) {
 	if cfg.MaxWheelMMs <= 0 || cfg.MaxWheelMMs > 500 {
 		return nil, fmt.Errorf("maxWheelSpeed must be 1-500, got %d", cfg.MaxWheelMMs)
 	}
+	if cfg.BRC.GPIOChip == "" {
+		cfg.BRC.GPIOChip = "gpiochip0"
+	}
 	if cfg.Media.Manage && cfg.Media.Service == "" {
 		return nil, errors.New("media.manage requires media.service")
 	}

pi/roverd/go.mod

@@ -4,6 +4,7 @@ go 1.25.4
 
 require (
 	github.com/tarm/serial v0.0.0-20180830185346-98f6abe2eb07
+	github.com/warthog618/go-gpiocdev v0.9.1
 	gopkg.in/yaml.v3 v3.0.1
 	nhooyr.io/websocket v1.8.17
 )

pi/roverd/go.sum

@@ -1,5 +1,17 @@
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+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/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=
 github.com/tarm/serial v0.0.0-20180830185346-98f6abe2eb07/go.mod h1:kDXzergiv9cbyO7IOYJZWg1U88JhDg3PB6klq9Hg2pA=
+github.com/warthog618/go-gpiocdev v0.9.1 h1:pwHPaqjJfhCipIQl78V+O3l9OKHivdRDdmgXYbmhuCI=
+github.com/warthog618/go-gpiocdev v0.9.1/go.mod h1:dN3e3t/S2aSNC+hgigGE/dBW8jE1ONk9bDSEYfoPyl8=
+github.com/warthog618/go-gpiosim v0.1.1 h1:MRAEv+T+itmw+3GeIGpQJBfanUVyg0l3JCTwHtwdre4=
+github.com/warthog618/go-gpiosim v0.1.1/go.mod h1:YXsnB+I9jdCMY4YAlMSRrlts25ltjmuIsrnoUrBLdqU=
 golang.org/x/sys v0.38.0 h1:3yZWxaJjBmCWXqhN1qh02AkOnCQ1poK6oF+a7xWL6Gc=
 golang.org/x/sys v0.38.0/go.mod h1:OgkHotnGiDImocRcuBABYBEXf8A9a87e/uXjp9XT3ks=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=

pi/roverd/roverd.sample.yaml

@@ -6,6 +6,7 @@ serial:
   baud: 115200
 brc:
   gpioPin: 17
+  gpioChip: gpiochip0
   pulseEvery: 1m
   pulseWidth: 1s
 battery:

pi/roverd/roverd.yaml

@@ -6,6 +6,7 @@ serial:
   baud: 115200
 brc:
   gpioPin: 17
+  gpioChip: gpiochip0
   pulseEvery: 1m
   pulseWidth: 1s
 battery: