SRF node - add ability to set time interval

to close #338

hardware/PiSrf/README.md

@@ -23,8 +23,10 @@ These can be any spare valid Pi GPIO pins. e.g.
 
         7,11
 
+You can also set the repeat frequency of measurements - default 0.5 seconds.
+
 Outputs a `msg.payload` with a number representing the range in cm.
 
-Produces one measure every 0.5s - but only if the distance is different from the previous reading.
+Produces one measure every 0.5s (by default) - but only if the distance is different from the previous reading.
 
 **Note:** we are using the actual physical pin numbers on connector P1 as they are easier to locate.

hardware/PiSrf/nrsrf.py

@@ -15,6 +15,7 @@ GPIO.setwarnings(False)
 ECHO    = 0
 TRIGGER = 0
 OLD = 0
+SLEEP = 0.5
 
 def Measure():
     start = 0
@@ -48,13 +49,14 @@ def Measure():
 # Main program loop
 if len(sys.argv) > 1:
     pins = sys.argv[1].lower().split(',')
-    if len(pins) != 2:
-        print "Bad number of pins supplied"
+    if len(pins) != 3:
+        print "Bad parameters supplied"
         print pins
         sys.exit(0)
 
     TRIGGER = int(pins[0])
     ECHO    = int(pins[1])
+    SLEEP   = float(pins[2])
 
     GPIO.setmode(GPIO.BOARD)        # Use GPIO BOARD numbers
     GPIO.setup(TRIGGER, GPIO.OUT)   # Trigger
@@ -72,7 +74,7 @@ if len(sys.argv) > 1:
             if distance != OLD:
                 print(distance)
                 OLD = distance
-            time.sleep(0.5)
+            time.sleep(SLEEP)
         except:                     # try to clean up on exit
             print("0.0");
             GPIO.cleanup(TRIGGER)
@@ -81,5 +83,5 @@ if len(sys.argv) > 1:
 
 else:
     print "Bad params"
-    print "    sudo nrsrf.py trigger_pin,echo_pin"
+    print "    sudo nrsrf.py trigger_pin,echo_pin,rate_in_seconds"
     sys.exit(0)

hardware/PiSrf/package.json

@@ -1,6 +1,6 @@
 {
     "name"          : "node-red-node-pisrf",
-    "version"       : "0.0.5",
+    "version"       : "0.1.0",
     "description"   : "A Node-RED node for a Raspberry Pi to use a SRF04 or SRF05 range finder",
     "dependencies"  : {
     },

hardware/PiSrf/pisrf.html

@@ -4,11 +4,14 @@
         <label for="node-input-pins"><i class="fa fa-circle"></i> Pins</label>
         <input type="text" id="node-input-pins" placeholder="Trigger,Echo">
     </div>
+    <div class="form-row">
+        <label for="node-input-pulse"><i class="fa fa-clock-o"></i> Repeat (S)</label>
+        <input type="text" id="node-input-pulse" placeholder="time between readings">
+    </div>
     <div class="form-row">
         <label for="node-input-topic"><i class="fa fa-bars"></i> Topic</label>
         <input type="text" id="node-input-topic" placeholder="optional topic">
     </div>
-    <br/>
     <div class="form-row">
         <label for="node-input-name"><i class="fa fa-tag"></i> Name</label>
         <input type="text" id="node-input-name" placeholder="Name">
@@ -20,7 +23,7 @@
 <script type="text/x-red" data-help-name="rpi-srf">
     <p>Raspberry Pi input from an SRF04 or SRF05 ultrasonic range finder.</p>
     <p>Outputs a <code>msg.payload</code> with a number representing the range in cm.</p>
-    <p>Produces one measure every 0.5s - but only if the distance is different from the previous reading.</p>
+    <p>Produces one measurement every 0.5s (default) - but only if the distance is different from the previous reading.</p>
     <p><b>Note:</b> we are using the actual physical pin numbers on connector P1 as they are easier to locate.</p>
 </script>
 
@@ -31,6 +34,7 @@
         defaults: {
             name: { value:"" },
             topic: { value:"SRF" },
+            pulse: {value:"0.5" },
             pins: { value:"", required:true, validate:RED.validators.regex(/^\d+,\d+$/) }
         },
         inputs:0,

hardware/PiSrf/pisrf.js

@@ -26,12 +26,13 @@ module.exports = function(RED) {
         RED.nodes.createNode(this, n);
         this.topic = n.topic;
         this.pins = n.pins;
+        this.pins += ","+(n.pulse || 0.5);
         var node = this;
 
         if (node.pins !== undefined) {
             node.child = spawn(gpioCommand, [node.pins]);
             node.running = true;
-            if (RED.settings.verbose) { node.log("pin: " + node.pins + " :"); }
+            if (RED.settings.verbose) { node.log("parameters: " + node.pins + " :"); }
 
             node.child.stdout.on('data', function(data) {
                 if (RED.settings.verbose) { node.log("out: " + data + " :"); }
@@ -59,7 +60,7 @@ module.exports = function(RED) {
 
         }
         else {
-            node.error("Invalid GPIO pins: " + node.pin);
+            node.error("Invalid Parameters: " + node.pins);
         }
 
         var wfi = function(done) {