extend examples

CHANGELOG.md

@@ -6,6 +6,7 @@ SPDX-License-Identifier: MIT
 ## [Unreleased](https://github.com/warthog618/gpiod/compare/v0.9.0...HEAD)
 
 - add *FindLine* functions to *Chip* and global.
+- rework and extend examples.
 
 ## v0.9.0 - 2024-03-16
 

README.md

@@ -162,7 +162,7 @@ l.SetValue(1)     // Set line active
 l.SetValue(0)     // Set line inactive
 ```
 
-Also refer to the [blinker](example/blinker/blinker.go) example.
+Also refer to the [toggle_line_value](examples/toggle_line_value/main.go) example.
 
 For collections of lines, all lines are set simultaneously using the
 [*SetValues*](https://pkg.go.dev/github.com/warthog618/go-gpiocdev#Lines.SetValues)
@@ -214,7 +214,7 @@ Note that the *Close* waits for the event handler to return and so must not be
 called from the event handler context - it should be called from a separate
 goroutine.
 
-Also see the [watcher](example/watcher/watcher.go) example.
+Also see the [watch_line_value](examples/watch_line_value/main.go) example.
 
 ### Line Configuration
 

examples/find_line_by_name/.gitignore

@@ -0,0 +1,4 @@
+# SPDX-FileCopyrightText: 2019 Kent Gibson <[email protected]>.
+#
+# SPDX-License-Identifier: CC0-1.0
+find_line_by_name

examples/find_line_by_name/main.go

@@ -0,0 +1,30 @@
+// SPDX-FileCopyrightText: 2024 Kent Gibson <[email protected]>
+//
+// SPDX-License-Identifier: MIT
+
+//go:build linux
+// +build linux
+
+// A simple example that finds a line by name.
+package main
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/warthog618/go-gpiocdev"
+)
+
+// Finds the chip and offset of a named line.
+func main() {
+	name := "GPIO22"
+	if len(os.Args) > 1 {
+		name = os.Args[1]
+	}
+	chip, offset, err := gpiocdev.FindLine(name)
+	if err != nil {
+		fmt.Printf("Finding line %s returned error: %s\n", name, err)
+		os.Exit(1)
+	}
+	fmt.Printf("%s:%d %s\n", chip, offset, name)
+}

examples/get_chip_info/.gitignore

@@ -0,0 +1,4 @@
+# SPDX-FileCopyrightText: 2019 Kent Gibson <[email protected]>.
+#
+# SPDX-License-Identifier: CC0-1.0
+get_chip_info

examples/get_chip_info/main.go

@@ -0,0 +1,28 @@
+// SPDX-FileCopyrightText: 2020 Kent Gibson <[email protected]>
+//
+// SPDX-License-Identifier: MIT
+
+//go:build linux
+// +build linux
+
+// A simple example that read the info for gpiochip0.
+package main
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/warthog618/go-gpiocdev"
+)
+
+// Reads the info for gpiochip0.
+func main() {
+	c, err := gpiocdev.NewChip("gpiochip0")
+	if err != nil {
+		fmt.Printf("Opening chip returned error: %s\n", err)
+		os.Exit(1)
+	}
+	defer c.Close()
+
+	fmt.Printf("%s (%s): %d lines\n", c.Name, c.Label, c.Lines())
+}

examples/get_line_info/.gitignore

@@ -0,0 +1,4 @@
+# SPDX-FileCopyrightText: 2019 Kent Gibson <[email protected]>.
+#
+# SPDX-License-Identifier: CC0-1.0
+get_line_info

examples/get_line_info/main.go

@@ -0,0 +1,33 @@
+// SPDX-FileCopyrightText: 2020 Kent Gibson <[email protected]>
+//
+// SPDX-License-Identifier: MIT
+
+//go:build linux
+// +build linux
+
+// A simple example that read the info for line 22 on gpiochip0.
+package main
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/warthog618/go-gpiocdev"
+)
+
+// Reads the info for line 22 on gpiochip0.
+func main() {
+	c, err := gpiocdev.NewChip("gpiochip0")
+	if err != nil {
+		fmt.Printf("Opening chip returned error: %s\n", err)
+		os.Exit(1)
+	}
+	defer c.Close()
+
+	info, err := c.LineInfo(22)
+	if err != nil {
+		fmt.Printf("Reading line info returned error: %s\n", err)
+		os.Exit(1)
+	}
+	fmt.Printf("%v\n", info)
+}

examples/get_line_value/.gitignore

@@ -0,0 +1,4 @@
+# SPDX-FileCopyrightText: 2019 Kent Gibson <[email protected]>
+#
+# SPDX-License-Identifier: CC0-1.0
+get_line_value

examples/get_line_value/main.go

@@ -0,0 +1,30 @@
+// SPDX-FileCopyrightText: 2020 Kent Gibson <[email protected]>
+//
+// SPDX-License-Identifier: MIT
+
+//go:build linux
+// +build linux
+
+// A simple example that reads an input pin.
+package main
+
+import (
+	"fmt"
+
+	"github.com/warthog618/go-gpiocdev"
+)
+
+// This example reads line 22 on gpiochip0.
+func main() {
+	offset := 22
+	chip := "gpiochip0"
+	l, err := gpiocdev.RequestLine(chip, offset, gpiocdev.AsInput)
+	if err != nil {
+		panic(err)
+	}
+	defer l.Close()
+
+	values := map[int]string{0: "inactive", 1: "active"}
+	v, err := l.Value()
+	fmt.Printf("%s:%d %s\n", chip, offset, values[v])
+}

examples/get_multiple_line_values/.gitignore

@@ -0,0 +1,4 @@
+# SPDX-FileCopyrightText: 2019 Kent Gibson <[email protected]>
+#
+# SPDX-License-Identifier: CC0-1.0
+get_multiple_line_values

examples/get_multiple_line_values/main.go

@@ -0,0 +1,39 @@
+// SPDX-FileCopyrightText: 2020 Kent Gibson <[email protected]>
+//
+// SPDX-License-Identifier: MIT
+
+//go:build linux
+// +build linux
+
+// A simple example that reads multiple input pins.
+package main
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/warthog618/go-gpiocdev"
+)
+
+// This example reads lines 21 and 22 on gpiochip0.
+func main() {
+	offsets := []int{21, 22}
+	chip := "gpiochip0"
+	l, err := gpiocdev.RequestLines(chip, offsets, gpiocdev.AsInput)
+	if err != nil {
+		fmt.Printf("Requesting lines returned error: %s\n", err)
+		os.Exit(1)
+	}
+	defer l.Close()
+
+	values := map[int]string{0: "inactive", 1: "active"}
+	vv := []int{0, 0}
+	err = l.Values(vv)
+	if err != nil {
+		fmt.Printf("Reading values returned error: %s\n", err)
+		os.Exit(1)
+	}
+	for i, o := range offsets {
+		fmt.Printf("%s:%d %s\n", chip, o, values[vv[i]])
+	}
+}

examples/reconfigure_input_to_output/.gitignore

@@ -0,0 +1,4 @@
+# SPDX-FileCopyrightText: 2019 Kent Gibson <[email protected]>
+#
+# SPDX-License-Identifier: CC0-1.0
+reconfigure_input_to_output

examples/reconfigure_input_to_output/main.go

@@ -0,0 +1,45 @@
+// SPDX-FileCopyrightText: 2020 Kent Gibson <[email protected]>
+//
+// SPDX-License-Identifier: MIT
+
+//go:build linux
+// +build linux
+
+// A simple example that requests a line as an input and subsequently switches it to an output.
+// DO NOT run this on a platform where that line is externally driven.
+package main
+
+import (
+	"fmt"
+	"time"
+
+	"github.com/warthog618/go-gpiocdev"
+)
+
+// This example requests line 23 on gpiochip0 as an input then switches it to an output.
+// DO NOT run this on a platform where that line is externally driven.
+func main() {
+	offset := 23
+	chip := "gpiochip0"
+	l, err := gpiocdev.RequestLine(chip, offset, gpiocdev.AsInput)
+	if err != nil {
+		panic(err)
+	}
+	// revert line to input on the way out.
+	defer func() {
+		l.Reconfigure(gpiocdev.AsInput)
+		fmt.Printf("Input pin: %s:%d\n", chip, offset)
+		l.Close()
+	}()
+
+	values := map[int]string{0: "inactive", 1: "active"}
+	v, err := l.Value()
+	fmt.Printf("Read pin: %s:%d %s\n", chip, offset, values[v])
+
+	l.Reconfigure(gpiocdev.AsOutput(v))
+	fmt.Printf("Set pin %s:%d %s\n", chip, offset, values[v])
+	time.Sleep(500 * time.Millisecond)
+	v ^= 1
+	l.SetValue(v)
+	fmt.Printf("Set pin %s:%d %s\n", chip, offset, values[v])
+}

examples/select_watch_line_value/main.go

@@ -18,7 +18,6 @@ import (
 	"time"
 
 	"github.com/warthog618/go-gpiocdev"
-	"github.com/warthog618/go-gpiocdev/device/rpi"
 )
 
 func printEvent(evt gpiocdev.LineEvent) {
@@ -45,7 +44,7 @@ func printEvent(evt gpiocdev.LineEvent) {
 	}
 }
 
-// Watches GPIO 23 (Raspberry Pi J8-16) and reports when it changes state.
+// Watches line 23 on gpiochip0 and reports when it changes state.
 func main() {
 	echan := make(chan gpiocdev.LineEvent, 6)
 
@@ -57,12 +56,13 @@ func main() {
 			// if you want the handler to block, rather than dropping
 			// events when the channel fills then <- ctx.Done() instead
 			// to ensure that the handler can't be left blocked
-			fmt.Printf("event chan overflow - discarding event")
+			fmt.Println("event chan overflow - discarding event")
 		}
 	}
 
-	offset := rpi.J8p16
-	l, err := gpiocdev.RequestLine("gpiochip0", offset,
+	offset := 23
+	chip := "gpiochip0"
+	l, err := gpiocdev.RequestLine(chip, offset,
 		gpiocdev.WithPullUp,
 		gpiocdev.WithBothEdges,
 		gpiocdev.WithEventHandler(eh))
@@ -74,15 +74,15 @@ func main() {
 		os.Exit(1)
 	}
 
-	fmt.Printf("Watching Pin %d...\n", offset)
+	fmt.Printf("Watching Pin %s:%d...\n", chip, offset)
 	done := false
 	for !done {
 		select {
 		// depending on the application other cases could deal with other channels
 		case evt := <-echan:
 			printEvent(evt)
 		case <-ctx.Done():
-			fmt.Println("exiting...")
+			fmt.Println("select_watch_line_value exiting...")
 			l.Close()
 			done = true
 		}

examples/toggle_line_value/main.go

@@ -16,26 +16,27 @@ import (
 	"time"
 
 	"github.com/warthog618/go-gpiocdev"
-	"github.com/warthog618/go-gpiocdev/device/rpi"
 )
 
-// This example drives GPIO 22, which is pin J8-15 on a Raspberry Pi.
+// This example drives line 22 on gpiochip0.
 // The pin is toggled high and low at 1Hz with a 50% duty cycle.
-// Do not run this on a device which has this pin externally driven.
+// DO NOT run this on a device which has this pin externally driven.
 func main() {
-	offset := rpi.J8p15
+	offset := 22
+	chip := "gpiochip0"
 	v := 0
-	l, err := gpiocdev.RequestLine("gpiochip0", offset, gpiocdev.AsOutput(v))
+	l, err := gpiocdev.RequestLine(chip, offset, gpiocdev.AsOutput(v))
 	if err != nil {
 		panic(err)
 	}
 	// revert line to input on the way out.
 	defer func() {
 		l.Reconfigure(gpiocdev.AsInput)
+		fmt.Printf("Input pin %s:%d\n", chip, offset)
 		l.Close()
 	}()
 	values := map[int]string{0: "inactive", 1: "active"}
-	fmt.Printf("Set pin %d %s\n", offset, values[v])
+	fmt.Printf("Set pin %s:%d %s\n", chip, offset, values[v])
 
 	// capture exit signals to ensure pin is reverted to input on exit.
 	quit := make(chan os.Signal, 1)
@@ -44,10 +45,10 @@ func main() {
 
 	for {
 		select {
-		case <-time.After(2 * time.Second):
+		case <-time.After(500 * time.Millisecond):
 			v ^= 1
 			l.SetValue(v)
-			fmt.Printf("Set pin %d %s\n", offset, values[v])
+			fmt.Printf("Set pin %s:%d %s\n", chip, offset, values[v])
 		case <-quit:
 			return
 		}

examples/toggle_multiple_line_values/.gitignore

@@ -0,0 +1,4 @@
+# SPDX-FileCopyrightText: 2019 Kent Gibson <[email protected]>
+#
+# SPDX-License-Identifier: CC0-1.0
+toggle_multiple_line_values