Add MAX17048 battery voltage measurement script

Battery_Voltage_Measure/get_battery.py

@@ -0,0 +1,90 @@
+#!/usr/bin/env python3
+import smbus2, time, collections
+from datetime import timedelta
+
+class MAX17048:
+    def __init__(self, i2c_bus=13, i2c_address=0x36):
+        self.bus = smbus2.SMBus(i2c_bus)
+        self.address = i2c_address
+
+    def _read_u16(self, reg):
+        b = self.bus.read_i2c_block_data(self.address, reg, 2)
+        return (b[0] << 8) | b[1]
+
+    def read_voltage(self):
+        # VCELL 0x02–0x03: 78.125 µV/LSB (1.25 mV / 16)
+        raw = self._read_u16(0x02)
+        uV = raw * 78.125
+        return uV / 1_000_000.0
+
+    def read_soc(self):
+        # SOC 0x04–0x05: MSB integer %, LSB in 1/256 %
+        raw = self._read_u16(0x04)
+        return ((raw >> 8) & 0xFF) + ((raw & 0xFF) / 256.0)
+
+    def read_rate(self):
+        # CRATE 0x16–0x17: signed, LSB ≈ 0.208 %/h
+        raw = self._read_u16(0x16)
+        if raw & 0x8000:
+            raw = -((~raw & 0xFFFF) + 1)
+        return raw * 0.208
+
+    def close(self):
+        self.bus.close()
+
+def fmt_eta(hours):
+    if hours is None or hours <= 0 or hours > 1e4:
+        return "ETA: n/a"
+    t = int(hours * 3600)
+    h, m = divmod(t // 60, 60)
+    return f"ETA: {h}h{m:02d}m"
+
+if __name__ == "__main__":
+    g = MAX17048()
+    try:
+        # Keep last ~120 seconds of (time,soc) for slope-based ETA
+        hist = collections.deque(maxlen=120)
+
+        while True:
+            try:
+                v = g.read_voltage()
+                soc = g.read_soc()
+                rate = g.read_rate()  # % per hour, signed
+
+                # --- ETA from CRATE ---
+                eta_h = None
+                if abs(rate) > 0.05:  # ignore tiny noise
+                    if rate < 0:
+                        eta_h = soc / (-rate)            # to empty
+                    else:
+                        eta_h = max(0.0, (100.0 - soc) / rate)  # to full
+
+                # --- Fallback: slope-based ETA over recent history ---
+                now = time.time()
+                hist.append((now, soc))
+                if eta_h is None and len(hist) >= 30:  # need ~30s of data
+                    t0, s0 = hist[0]
+                    t1, s1 = hist[-1]
+                    dt_h = max((t1 - t0) / 3600.0, 1e-6)
+                    slope = (s1 - s0) / dt_h  # % per hour (signed)
+                    if slope < -0.1:
+                        eta_h = soc / (-slope)
+                    elif slope > 0.1:
+                        eta_h = max(0.0, (100.0 - soc) / slope)
+
+                parts = []
+                if v is not None:   parts.append(f"{v:4.2f} V")
+                if soc is not None: parts.append(f"{soc:6.2f} %")
+                if rate is not None:parts.append(f"{rate:+6.2f} %/h")
+                parts.append(fmt_eta(eta_h))
+                print(" | ".join(parts))
+
+            except OSError as e:
+                print(f"I2C error: {e}")
+
+            time.sleep(1)
+
+    except KeyboardInterrupt:
+        pass
+    finally:
+        g.close()