bringup and order sensors

bringup/calibrate.py

@@ -0,0 +1,39 @@
+"""Battery voltage calibration math.
+
+Firmware model (power_mgmt.c:278):
+    V_bat = mV * V_SENS_K + V_SENS_OFFSET
+"""
+
+from __future__ import annotations
+
+from dataclasses import dataclass
+
+
+@dataclass
+class CalResult:
+    k: float
+    offset: float
+    note: str
+
+
+def single_point_offset(bat_mv: float, v_true: float, k: float) -> CalResult:
+    """Fix K, solve for OFFSET so that V_bat(bat_mv) == v_true."""
+    offset = v_true - bat_mv * k
+    return CalResult(k=k, offset=offset, note="single-point offset")
+
+
+def two_point(
+    bat_mv_1: float, v_true_1: float,
+    bat_mv_2: float, v_true_2: float,
+) -> CalResult:
+    """Solve for K and OFFSET from two (mV, V) pairs."""
+    dmv = bat_mv_2 - bat_mv_1
+    if abs(dmv) < 1e-3:
+        raise ValueError("Two calibration points are too close — pick wider V")
+    k = (v_true_2 - v_true_1) / dmv
+    offset = v_true_1 - bat_mv_1 * k
+    return CalResult(k=k, offset=offset, note="two-point")
+
+
+def verify(bat_mv: float, cal: CalResult) -> float:
+    return bat_mv * cal.k + cal.offset