m 2 led-fader: init

2configs/deployment/led-fader/default.nix

@@ -0,0 +1,27 @@
+{ config, lib, pkgs, ... }:
+
+with import <stockholm/lib>;
+let
+  mq = "192.168.8.11";
+in {
+  systemd.services.led-fader  = {
+    description = "Send led change to message queue";
+    environment = {
+      NIX_PATH = "/var/src";
+    };
+    wantedBy = [ "multi-user.target" ];
+    path = with pkgs; [
+      nix # nix-shell
+      mosquitto #mosquitto_pub
+      bash # nix-shell
+    ];
+    serviceConfig = {
+      # User = "nobody"; # need a user with permissions to run nix-shell
+      ExecStart = pkgs.writeDash "run-fader" ''
+      ${./fade.py} --add-empty --mode chain 3 loop --skip-unchanged 0.002 0.1 \
+        | mosquitto_pub -h ${mq} -p 1883 -l -t '/leds/nodemcu-switcher/set'
+      '';
+      PrivateTmp = true;
+    };
+  };
+}

2configs/deployment/led-fader/fade.py

@@ -0,0 +1,78 @@
+#! /usr/bin/env nix-shell
+#! nix-shell -i python3 -p python3 python35Packages.docopt
+""" usage: run [options] NUMLEDS (loop [--skip-unchanged] [STEP] [DELAY]|single STARTVAL)
+
+    --add-empty       essentially add a single empty led in front, does not count into NUMLEDS
+
+    --mode=TYPE         mode of fading (Default: chain)
+    --output=TYPE       output type, either json or raw (Default: json)
+    --skip-unchanged    if the value in the loop is unchanged, skip the output
+
+running with loop this script essentially becomes a generator which outputs the
+next value each "DELAY"
+single returns a single output with STARTVAL as starting point for the first led
+
+NUMLEDS is the number of leds to output data for (--add-empty does not count in here)
+STEP defaults to 0.01
+DELAY defaults to 1 second
+
+"""
+from docopt import docopt
+import time
+from colorsys import hsv_to_rgb
+import json
+import sys
+
+def calc_chain(numleds,val):
+    divisor = 1.0 /  numleds
+    ret = []
+    for i in range(numleds):
+        v = float(divisor * i + val) % 1
+        r,g,b = hsv_to_rgb(v,0.9,1)
+        ret.append([int(r*255),
+                    int(g*255),
+                    int(b*255)])
+    return ret
+
+def calc_single(numleds,val):
+    ret = []
+    for i in range(numleds):
+        r,g,b = hsv_to_rgb(val,1,1)
+        ret.append([int(r*255),
+                    int(g*255),
+                    int(b*255)])
+    return ret
+
+def main():
+    args = docopt(__doc__)
+    numleds = int(args['NUMLEDS'])
+    mode = args['--mode']
+    step = float(args['STEP'] or 0.01)
+    delay = float(args['DELAY'] or 1)
+    val = float(args['STARTVAL'] or 0)
+    last = []
+    while True:
+        if mode == "chain":
+            ret = calc_chain(numleds,val)
+        elif mode == "single":
+            ret = calc_single(numleds,val)
+
+        if args['--add-empty']:
+            ret.insert(0,[0,0,0])
+
+        # early serialization makes comparsion easy
+        ret = json.dumps(ret)
+        if not (args['--skip-unchanged'] and last == ret):
+            last = ret
+            print(ret)
+            sys.stdout.flush()
+        if args['single']:
+            break
+        else:
+            val += step % 1
+            time.sleep(delay)
+
+
+
+if __name__ == "__main__":
+    main()