Temp spike battery improvements (#21)

Author: h3ss

src/thermopro_ble/parser.py

@@ -8,6 +8,7 @@
 from __future__ import annotations
 
 import logging
+from math import tanh
 from struct import Struct
 
 from bluetooth_data_tools import short_address
@@ -27,8 +28,17 @@
 UNPACK_TEMP_HUMID = Struct("<hB").unpack
 UNPACK_SPIKE_TEMP = Struct("<BHHH").unpack
 
-TP96_MAX_BAT = 2880
-TP96_MIN_BAT = 2000  # ??
+
+# TP96x battery values appear to be a voltage reading, probably in millivolts.
+# This means that calculating battery life from it is a non-linear function.
+# Examining the curve, it looked fairly close to a curve from the tanh function.
+# So, I created a script to use Tensorflow to optimize an equation in the format
+# A*tanh(B*x+C)+D
+# Where A,B,C,D are the variables to optimize for.  This yielded the below function
+def tp96_battery(voltage: int) -> float:
+    raw = 52.317286 * tanh(voltage / 273.624277936 - 8.76485439394) + 51.06925
+    clamped = max(0, min(raw, 100))
+    return round(clamped, 2)
 
 
 class ThermoProBluetoothDeviceData(BluetoothData):
@@ -68,22 +78,18 @@ def _start_update(self, service_info: BluetoothServiceInfo) -> None:
             return
 
         if name.startswith("TP96"):
-            bat_range = TP96_MAX_BAT - TP96_MIN_BAT
-
             # TP96 has a different format
             # It has an internal temp probe and an ambient temp probe
             (
                 probe_zero_indexed,
                 internal_temp,
-                battery,
+                battery_voltage,
                 ambient_temp,
             ) = UNPACK_SPIKE_TEMP(data)
             probe_one_indexed = probe_zero_indexed + 1
             internal_temp = internal_temp - 30
             ambient_temp = ambient_temp - 30
-            battery_percent = ((battery - TP96_MIN_BAT) / bat_range) * 100
-            if battery_percent > 100:
-                battery_percent = 100
+            battery_percent = tp96_battery(battery_voltage)
             self.update_predefined_sensor(
                 SensorLibrary.TEMPERATURE__CELSIUS,
                 internal_temp,

tests/test_parser.py

@@ -339,7 +339,7 @@ def test_tp960r():
             DeviceKey(key="battery_probe_1", device_id=None): SensorValue(
                 device_key=DeviceKey(key="battery_probe_1", device_id=None),
                 name="Probe 1 Battery",
-                native_value=11,
+                native_value=9,
             ),
         },
         binary_entity_descriptions={},
@@ -405,7 +405,7 @@ def test_tp960r():
             DeviceKey(key="battery_probe_1", device_id=None): SensorValue(
                 device_key=DeviceKey(key="battery_probe_1", device_id=None),
                 name="Probe 1 Battery",
-                native_value=11,
+                native_value=9,
             ),
         },
         binary_entity_descriptions={},
@@ -475,7 +475,7 @@ def test_tp962r():
             DeviceKey(key="battery_probe_2", device_id=None): SensorValue(
                 device_key=DeviceKey(key="battery_probe_2", device_id=None),
                 name="Probe 2 Battery",
-                native_value=99,
+                native_value=100.0,
             ),
         },
         binary_entity_descriptions={},
@@ -567,12 +567,12 @@ def test_tp962r():
             DeviceKey(key="battery_probe_1", device_id=None): SensorValue(
                 device_key=DeviceKey(key="battery_probe_1", device_id=None),
                 name="Probe 1 Battery",
-                native_value=66,
+                native_value=82,
             ),
             DeviceKey(key="battery_probe_2", device_id=None): SensorValue(
                 device_key=DeviceKey(key="battery_probe_2", device_id=None),
                 name="Probe 2 Battery",
-                native_value=99,
+                native_value=100.0,
             ),
             DeviceKey(key="internal_temperature_probe_2", device_id=None): SensorValue(
                 device_key=DeviceKey(