From 9047e043a826aa16e9f9b112469ef4b0368d0f15 Mon Sep 17 00:00:00 2001
From: "Adrian A. Baumann" <ade@adebaumann.com>
Date: Tue, 17 Mar 2026 01:54:34 +0100
Subject: [PATCH] Added calibrated meter (usually for ampere meter)

---
 mipyiot/calibratedmeter.py | 95 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 95 insertions(+)
 create mode 100644 mipyiot/calibratedmeter.py

diff --git a/mipyiot/calibratedmeter.py b/mipyiot/calibratedmeter.py
new file mode 100644
index 0000000..2dfca3b
--- /dev/null
+++ b/mipyiot/calibratedmeter.py
@@ -0,0 +1,95 @@
+from machine import PWM, Pin
+from array import array
+
+class CalibratedMeter:
+    def __init__(self, pin, freq=1000, input_min=0, input_max=100,
+                 output_min=0, output_max=65535):
+        self._pwm = PWM(Pin(pin), freq=freq)
+        self._input_min = input_min
+        self._input_max = input_max
+        self._output_min = output_min
+        self._output_max = output_max
+        self._cal_inputs = array('f', [input_min, input_max])
+        self._cal = array('f', [output_min, output_max])
+
+    # --- Input range property ---
+    @property
+    def input_range(self):
+        return (self._input_min, self._input_max)
+
+    @input_range.setter
+    def input_range(self, value):
+        self._input_min, self._input_max = value
+
+    # --- Output range property ---
+    @property
+    def output_range(self):
+        return (self._output_min, self._output_max)
+
+    @output_range.setter
+    def output_range(self, value):
+        self._output_min, self._output_max = value
+
+    # --- Calibration ---
+    def set_calibration(self, points):
+        """
+        points: list of (input_value, duty_cycle) tuples
+                input_value: in real-world units
+                duty_cycle: must be within output_min and output_max
+        Example:
+            meter.set_calibration([
+                (0,   0),
+                (25,  170),
+                (50,  335),
+                (75,  508),
+                (100, 1023),
+            ])
+        """
+        points = sorted(points, key=lambda p: p[0])
+
+        # Sanity checks
+        for i, (inp, out) in enumerate(points):
+            if not (self._output_min <= out <= self._output_max):
+                raise ValueError(
+                    f"Calibration point {i}: duty {out} outside output range "
+                    f"[{self._output_min}, {self._output_max}]"
+                )
+            if not (self._input_min <= inp <= self._input_max):
+                raise ValueError(
+                    f"Calibration point {i}: input {inp} outside input range "
+                    f"[{self._input_min}, {self._input_max}]"
+                )
+
+        self._cal_inputs = array('f', [p[0] for p in points])
+        self._cal = array('f', [p[1] for p in points])
+
+    # --- Internal helpers ---
+    def _interpolate(self, value):
+        """Linearly interpolate duty cycle from calibration table."""
+        if value <= self._cal_inputs[0]:
+            return self._cal[0]
+        if value >= self._cal_inputs[-1]:
+            return self._cal[-1]
+        for i in range(len(self._cal_inputs) - 1):
+            x0, x1 = self._cal_inputs[i], self._cal_inputs[i + 1]
+            if x0 <= value <= x1:
+                y0, y1 = self._cal[i], self._cal[i + 1]
+                t = (value - x0) / (x1 - x0)
+                return y0 + t * (y1 - y0)
+        return self._cal[-1]
+
+    # --- Output ---
+    def write(self, value):
+        """Write a value in real-world units to the meter."""
+        value = max(self._input_min, min(self._input_max, value))
+        duty = int(self._interpolate(value))
+        duty = max(self._output_min, min(self._output_max, duty))
+        self._pwm.duty_u16(duty)
+
+    def off(self):
+        """Set meter to zero."""
+        self._pwm.duty_u16(self._output_min)
+
+    def full(self):
+        """Set meter to full scale."""
+        self._pwm.duty_u16(self._output_max)