ism330dl: Add two-point temperature calibration methods.

lib/ism330dl/ism330dl/device.py

@@ -16,6 +16,9 @@ def __init__(self, i2c, address=ISM330DL_I2C_DEFAULT_ADDR):
         self._accel_scale = ACCEL_FS_2G
         self._gyro_scale = GYRO_FS_250DPS
 
+        self._temp_gain = 1.0
+        self._temp_offset = 0.0
+
         self.check_device()
         self.reset()
         self.configure_accel(ACCEL_ODR_104HZ, ACCEL_FS_2G)
@@ -149,8 +152,28 @@ def gyroscope_rads(self):
         return tuple(v * pi / 180.0 for v in dps)
 
     def temperature_c(self):
-        raw = self.temperature_raw()
-        return TEMP_OFFSET + raw / TEMP_SENSITIVITY
+        factory = TEMP_OFFSET + self.temperature_raw() / TEMP_SENSITIVITY
+        return self._temp_gain * factory + self._temp_offset
+
+    def set_temp_offset(self, offset_c):
+        """Set a temperature offset in °C (gain remains 1.0)."""
+        self._temp_gain = 1.0
+        self._temp_offset = float(offset_c)
+
+    def calibrate_temperature(self, ref_low, measured_low, ref_high, measured_high):
+        """Two-point calibration from reference measurements.
+
+        Args:
+            ref_low: reference temperature at the low point (°C).
+            measured_low: sensor reading at the low point (°C).
+            ref_high: reference temperature at the high point (°C).
+            measured_high: sensor reading at the high point (°C).
+        """
+        delta = float(measured_high - measured_low)
+        if delta == 0.0:
+            raise ValueError("measured_low and measured_high must differ")
+        self._temp_gain = float(ref_high - ref_low) / delta
+        self._temp_offset = float(ref_low) - self._temp_gain * float(measured_low)
 
     def orientation(self):
         ax, ay, az = self.acceleration_g()

tests/scenarios/board_temperature_comparison.yaml

@@ -10,6 +10,7 @@ drivers:
   - wsen-hids
   - wsen-pads
   - lis2mdl
+  - ism330dl
 
 tests:
   - name: "Read all temperature sensors"
@@ -20,6 +21,7 @@ tests:
       sys.path.insert(0, '/remote/wsen-hids')
       sys.path.insert(0, '/remote/wsen-pads')
       sys.path.insert(0, '/remote/lis2mdl')
+      sys.path.insert(0, '/remote/ism330dl')
 
       from machine import I2C
       from time import sleep_ms
@@ -52,6 +54,12 @@ tests:
       mag = LIS2MDL(i2c)
       temps['LIS2MDL'] = mag.read_temperature_c()
 
+      # ISM330DL (auxiliary, offset not guaranteed by datasheet)
+      from ism330dl.device import ISM330DL
+      imu = ISM330DL(i2c)
+      sleep_ms(200)  # stabilize after reset
+      temps['ISM330DL'] = imu.temperature_c()
+
       # Print comparison table
       print('--- Temperature Comparison ---')
       for name, t in temps.items():
@@ -108,6 +116,7 @@ tests:
       sys.path.insert(0, '/remote/wsen-hids')
       sys.path.insert(0, '/remote/wsen-pads')
       sys.path.insert(0, '/remote/lis2mdl')
+      sys.path.insert(0, '/remote/ism330dl')
 
       from machine import I2C
       from time import sleep_ms
@@ -131,6 +140,10 @@ tests:
       from lis2mdl.device import LIS2MDL
       mag = LIS2MDL(i2c)
 
+      from ism330dl.device import ISM330DL
+      imu = ISM330DL(i2c)
+      sleep_ms(200)  # stabilize after reset
+
       # Read reference just before each sensor to minimize drift
       ref_t = ref.temperature()
       hts_t = hts.temperature()
@@ -141,34 +154,41 @@ tests:
       ref_t3 = ref.temperature()
       mag_t = mag.read_temperature_c()
 
+      ref_t4 = ref.temperature()
+      imu_t = imu.temperature_c()
+
       print('--- Before offset alignment ---')
       print('  WSEN-HIDS (ref): ' + str(round(ref_t, 2)) + ' C')
       print('  HTS221:          ' + str(round(hts_t, 2)) + ' C')
       print('  WSEN-PADS:       ' + str(round(pads_t, 2)) + ' C')
       print('  LIS2MDL:         ' + str(round(mag_t, 2)) + ' C')
+      print('  ISM330DL:        ' + str(round(imu_t, 2)) + ' C')
 
-      spread_before = max(hts_t, pads_t, mag_t, ref_t) - min(hts_t, pads_t, mag_t, ref_t)
+      spread_before = max(hts_t, pads_t, mag_t, imu_t, ref_t) - min(hts_t, pads_t, mag_t, imu_t, ref_t)
       print('  Spread: ' + str(round(spread_before, 2)) + ' C')
 
       # Apply offset to align each sensor to the reference reading
       hts.set_temp_offset(ref_t - hts_t)
       pads.set_temp_offset(ref_t2 - pads_t)
       mag.set_temp_offset(ref_t3 - mag_t)
+      imu.set_temp_offset(ref_t4 - imu_t)
 
       # Re-read after offset alignment
       sleep_ms(50)
-      ref_t4 = ref.temperature()
+      ref_t5 = ref.temperature()
       hts_t2 = hts.temperature()
       pads_t2 = pads.temperature()
       mag_t2 = mag.read_temperature_c()
+      imu_t2 = imu.temperature_c()
 
       print('--- After offset alignment ---')
-      print('  WSEN-HIDS (ref): ' + str(round(ref_t4, 2)) + ' C')
+      print('  WSEN-HIDS (ref): ' + str(round(ref_t5, 2)) + ' C')
       print('  HTS221:          ' + str(round(hts_t2, 2)) + ' C')
       print('  WSEN-PADS:       ' + str(round(pads_t2, 2)) + ' C')
       print('  LIS2MDL:         ' + str(round(mag_t2, 2)) + ' C')
+      print('  ISM330DL:        ' + str(round(imu_t2, 2)) + ' C')
 
-      spread_after = max(hts_t2, pads_t2, mag_t2, ref_t4) - min(hts_t2, pads_t2, mag_t2, ref_t4)
+      spread_after = max(hts_t2, pads_t2, mag_t2, imu_t2, ref_t5) - min(hts_t2, pads_t2, mag_t2, imu_t2, ref_t5)
       print('  Spread: ' + str(round(spread_after, 2)) + ' C')
 
       # After alignment, spread should be < 2°C

tests/scenarios/ism330dl.yaml

@@ -145,6 +145,33 @@ tests:
     expect_true: true
     mode: [mock]
 
+  - name: "Temperature offset shifts reading"
+    action: script
+    script: |
+      dev.set_temp_offset(-2.5)
+      result = abs(dev.temperature_c() - 22.5) < 0.1
+    expect_true: true
+    mode: [mock]
+
+  - name: "Temperature with two-point calibration"
+    action: script
+    script: |
+      dev.calibrate_temperature(20.0, 25.0, 30.0, 35.0)
+      result = dev.temperature_c()
+    expect_range: [19.0, 21.0]
+    mode: [mock]
+
+  - name: "Calibration rejects equal measurements"
+    action: script
+    script: |
+      try:
+          dev.calibrate_temperature(20.0, 25.0, 30.0, 25.0)
+          result = False
+      except ValueError:
+          result = True
+    expect_true: true
+    mode: [mock]
+
   - name: "Temperature in plausible range"
     action: call
     method: temperature_c