feat: MQTT Support

Building on @jcassel's work in #40, this publishes scale changes
to mqtt via the Octoprint-MQTT plugin.

closes #39

Author: jcassel

README.md

@@ -24,6 +24,15 @@ or manually using this URL:
 
 Once you have wired up the HX711, it must be calibrated. This is a pretty straightforward process, and all you will need is an object of known weight. Attach the load cell to your printer with the printed bracket, then follow the instructions on the plugin's settings page.
 
+## MQTT
+
+If you would like weight messages published via MQTT, install and configure [Octoprint-MQTT](https://plugins.octoprint.org/plugins/mqtt/)
+
+Once it's configured correctly, this library will automatically detect it and start publishing messages in the following format:
+```
+baseTopic/plugin/filament_scale/filament_weight 171
+```
+
 ## Troubleshooting
 
 `NaN` may be occasionally displayed in the interface when the weight can't be read correctly. The cheap boards vary in quality and are a little sensitive to vibration/power stability. Ensure the cabling is secure, you have a sufficiently sized load cell, and a good power supply.
@@ -39,4 +48,4 @@ pip install OctoPrint Mock.GPIO
 pip install ".[development]"
 ```
 
-Running Tests: `pytest -v`
+Running Tests: `pytest -v`

filament_scale_enhanced/__init__.py

@@ -1,6 +1,7 @@
 # coding=utf-8
 from __future__ import absolute_import
 
+import flask
 import octoprint.plugin
 
 from .fse_version import VERSION as __version__  # noqa: F401
@@ -13,19 +14,20 @@
 
 
 # pylint: disable=too-many-ancestors
-class FilamentScalePlugin(octoprint.plugin.SettingsPlugin,
-                          octoprint.plugin.AssetPlugin,
-                          octoprint.plugin.TemplatePlugin,
-                          octoprint.plugin.StartupPlugin):
+class FilamentScalePlugin(
+    octoprint.plugin.SettingsPlugin,
+    octoprint.plugin.AssetPlugin,
+    octoprint.plugin.TemplatePlugin,
+    octoprint.plugin.StartupPlugin,
+):
 
     hx = None
     t = None
+    tq = None
 
     @staticmethod
     def get_template_configs():
-        return [
-            dict(type="settings", custom_bindings=True)
-        ]
+        return [dict(type="settings", custom_bindings=True)]
 
     @staticmethod
     def get_settings_defaults():
@@ -35,30 +37,84 @@ def get_settings_defaults():
             spool_weight=200,
             clockpin=21,
             datapin=20,
-            lastknownweight=0
+            lastknownweight=0,
         )
 
     @staticmethod
     def get_assets():
         return dict(
             js=["js/filament_scale.js"],
             css=["css/filament_scale.css"],
-            less=["less/filament_scale.less"]
+            less=["less/filament_scale.less"],
         )
 
+    def __init__(self):
+        super().__init__()
+        self.mqtt_publish = lambda *args, **kwargs: None
+        self.mqtt = False
+        self.mqtt_topic = ''
+        self.last_weight = 0
+        self.last_sent_weight = -1
+
     def on_startup(self, host, port):  # pylint: disable=unused-argument
-        self.hx = HX711(20, 21)
-        self.hx.set_reading_format("LSB", "MSB")
-        self.hx.reset()
-        self.hx.power_up()
-        self.t = octoprint.util.RepeatedTimer(3.0, self.check_weight)
-        self.t.start()
+        try:
+            self.hx = HX711(20, 21)
+            self.hx.set_reading_format("LSB", "MSB")
+            self.hx.reset()
+            self.hx.power_up()
+            self.t = octoprint.util.RepeatedTimer(3.0, self.check_weight)
+            self.t.start()
+            self.tq = octoprint.util.RepeatedTimer(10.0, self.send_weight_mqtt)
+            self.tq.start()
+        except Exception as err:  # pylint: disable=broad-exception-caught
+            self._logger.exception(err)
+
+    def on_after_startup(self):
+        helpers = self._plugin_manager.get_helpers("mqtt", "mqtt_publish")
+        if not helpers or "mqtt_publish" not in helpers:
+            self._logger.debug(
+                "MQTT plugin helpers not found scale value will not be published"
+            )
+            return
+
+        base_topic = self._settings.global_get(
+            ["plugins", "mqtt", "publish", "baseTopic"]
+        )
+        self.mqtt_topic = f"{base_topic.rstrip('/')}/plugin/{self._identifier}"
+        self._logger.debug("Topic: %s", self.mqtt_topic)
+
+        self.mqtt_publish = helpers["mqtt_publish"]
+        self.mqtt = True
+        self._logger.debug(
+            "MQTT plugIn Helpers Found. Scale value will be published"
+        )
+
+    def real_weight(self) -> int:
+        tare = self._settings.get(["tare"])
+        reference = self._settings.get(["reference_unit"])
+        spool = self._settings.get(["spool_weight"])
+        weight = (self.last_weight - tare) / reference
+        return int(weight) - int(spool)
+
+    def send_weight_mqtt(self):
+        if not self.mqtt:
+            return
+        real_weight = self.real_weight()
+        if real_weight == self.last_sent_weight:
+            return
+        self.last_sent_weight = real_weight
+        self.mqtt_publish(f'{self.mqtt_topic}/filament_weight', str(real_weight))
 
     def check_weight(self):
-        self.hx.power_up()
-        v = self.hx.read()
-        self._plugin_manager.send_plugin_message(self._identifier, v)
-        self.hx.power_down()
+        self._logger.debug("Begin hxRead")
+        try:
+            self.hx.power_up()
+            v = self.hx.read()
+            self.last_weight = v
+            self._plugin_manager.send_plugin_message(self._identifier, v)
+            self.hx.power_down()
+        except Exception as err:
+            self._logger.exception(err)
 
     # pylint: disable=line-too-long
     def get_update_information(self):
@@ -70,15 +126,13 @@ def get_update_information(self):
             filament_scale=dict(
                 displayName="Filament Scale Plugin",
                 displayVersion=self._plugin_version,
-
                 # version check: github repository
                 type="github_release",
                 user="techman83",
                 repo="Filament-Scale-Enhanced",
                 current=self._plugin_version,
-
                 # update method: pip
-                pip="https://github.com/techman83/Filament-Scale-Enhanced/releases/latest/download/Filament_Scale_Enhanced.zip"  # noqa: E501
+                pip="https://github.com/techman83/Filament-Scale-Enhanced/releases/latest/download/Filament_Scale_Enhanced.zip",  # noqa: E501
             )
         )