Add CT Clamp component (#559)

* Add CT Clamp component

* Update lint

* Some more fixes

* Make updates to work as an analog sensor consumer

* Remove unused imports
Update lint suggestions

* Move setup_priority to header

* Remove unused calibration value

* Remove Unique ID

- Will be auto generated

* Update to use loop and not slow down main loop

Co-authored-by: Otto Winter <otto@otto-winter.com>

esphome/components/ct_clamp/sensor.py

@@ -0,0 +1,27 @@
+import esphome.codegen as cg
+import esphome.config_validation as cv
+from esphome.components import sensor, voltage_sampler
+from esphome.const import CONF_SENSOR, CONF_ID, ICON_FLASH, UNIT_AMPERE
+
+AUTO_LOAD = ['voltage_sampler']
+
+CONF_SAMPLE_DURATION = 'sample_duration'
+
+ct_clamp_ns = cg.esphome_ns.namespace('ct_clamp')
+CTClampSensor = ct_clamp_ns.class_('CTClampSensor', sensor.Sensor, cg.PollingComponent)
+
+CONFIG_SCHEMA = sensor.sensor_schema(UNIT_AMPERE, ICON_FLASH, 2).extend({
+    cv.GenerateID(): cv.declare_id(CTClampSensor),
+    cv.Required(CONF_SENSOR): cv.use_id(voltage_sampler.VoltageSampler),
+    cv.Optional(CONF_SAMPLE_DURATION, default='200ms'): cv.positive_time_period_milliseconds,
+}).extend(cv.polling_component_schema('60s'))
+
+
+def to_code(config):
+    var = cg.new_Pvariable(config[CONF_ID])
+    yield cg.register_component(var, config)
+    yield sensor.register_sensor(var, config)
+
+    sens = yield cg.get_variable(config[CONF_SENSOR])
+    cg.add(var.set_source(sens))
+    cg.add(var.set_sample_duration(config[CONF_SAMPLE_DURATION]))