Add generic support for clamping sensor readings to positive values

Closes #56

examples/config.sample.full.yml

@@ -31,6 +31,7 @@ circuits:
           - Vägg vardagsrum
           - Vägg kök
           - Vägg arbetsrum
+      clamp: positive # Don't allow negative values
   # A IotaWatt main circuit, phase A/L1
   - name: Main L1
     type: main
@@ -144,6 +145,7 @@ circuits:
         unit: 100
         register: 866
         type: int16
+      clamp: positive
 
 #
 # Characteristics. Characteristics mean voltage and frequency, and potentially other non-power related readings.

src/eachwatt.ts

@@ -53,10 +53,16 @@ const mainPollerFunc = async (config: Config) => {
   // Poll characteristics sensors
   const characteristicsSensorData = await pollCharacteristicsSensors(now, config.characteristics)
 
-  // Round all numbers to one decimal point
+  // Post-process power sensor data
   for (const data of powerSensorData) {
     if (data.power !== undefined) {
+      // Round all numbers to one decimal point
       data.power = Number(data.power.toFixed(1))
+
+      // Optionally clamp values
+      if (data.circuit.sensor.clamp === 'positive') {
+        data.power = Math.max(0, data.power)
+      }
     }
   }
 

src/sensor.ts

@@ -36,6 +36,7 @@ export type CharacteristicsSensorPollFunction = (
 export interface PowerSensor {
   type: SensorType
   pollFunc: PowerSensorPollFunction
+  clamp?: 'positive'
 }
 
 export interface CharacteristicsSensor {

src/sensor/unmetered.ts

@@ -19,6 +19,6 @@ export const getSensorData: PowerSensorPollFunction = async (
   return {
     timestamp,
     circuit,
-    power: Math.max(parentWatts - unmeteredWatts, 0), // Don't allow negative values
+    power: parentWatts - unmeteredWatts,
   }
 }