lachlan · April 9, 2014 21:54 · Apr 9, 2014
diff --git a/cereal.go b/cereal.go
@@ -0,0 +1,83 @@
+package main
+
+import (
+  "encoding/base64"
+  "encoding/hex"
+  "github.com/docopt/docopt.go"
+  "github.com/tarm/goserial"
+  "log"
+  "strconv"
+)
+
+var version string = "0.0.1"
+var usage string = `cereal -- writes data to a serial port
+
+Usage:
+  cereal write [--device=<device>] [--baud=<baud>] [--base64 | --hex] <data>
+  cereal -h | --help
+  cereal --version
+
+Options:
+  -h --help         Show this screen.
+  --version         Show version.
+  --device=<device> The serial port to write the specified data to [default: COM1].
+  --baud=<baud>     The baud rate used when transmitting the specified data [default: 9600].
+  --base64          Data is provided as a base64-encoded string, for example "aGVsbG8=".
+  --hex             Data is provided as a hex-encoded string, for example "00fffa08".
+`
+
+func main() {
+  // parse the command line arguments
+  arguments, err := docopt.Parse(usage, nil, true, version, false)
+  if err != nil {
+    log.Fatal("Error: command line arguments could not be parsed: ", err)
+  }
+
+  // extract the command line arguments
+  data, _ := arguments["<data>"].(string)
+  base64Encoded, _ := arguments["--base64"].(bool)
+  hexEncoded, _ := arguments["--hex"].(bool)
+  device, _ := arguments["--device"].(string)
+  baud, _ := strconv.Atoi(arguments["--baud"].(string))
+  write, _ := arguments["write"].(bool)
+
+  if (write) {
+    // encode the data as a byte array using the specified encoding
+    var bytes []byte;
+    if (base64Encoded) {
+      bytes, err = base64.StdEncoding.DecodeString(data)
+      if err != nil {
+        log.Fatal("Error: base64-encoded data is malformed: ", err)
+      }
+    } else if (hexEncoded) {
+      bytes, err = hex.DecodeString(data)
+      if err != nil {
+        log.Fatal("Error: hex-encoded data is malformed: ", err)
+      }
+    } else {
+      bytes = []byte(data)
+    }
+
+    // open the serial port
+    c := &serial.Config{Name: device, Baud: baud}
+    handle, err := serial.OpenPort(c)
+    if err != nil {
+      log.Fatal("Error: device ", device, " could not be opened: ", err)
+    }
+    // close the serial port when done
+    defer handle.Close()
+
+    // write the data to the serial port
+    n, err := handle.Write(bytes)
+    if err != nil {
+      log.Fatal("Error: device ", device, " could not be written to: ", err)
+    }
+
+    // log the number of bytes written to the console
+    if (n == 1) {
+      log.Printf("%v byte written to device %v", n, device)
+    } else {
+      log.Printf("%v bytes written to device %v", n, device)
+    }
+  }
+}