DEV-958: use the ST datasheet accel sensitivity for the gen-2 LSM6DSV

SensorLSM6DSV derived accel sensitivity as 32768/(FS_g*9.80665), while the
firmware seed, the web SDK catalog and the driver's own gen-1 classes all use
the ST datasheet mg/LSB figure - a 0.0576% split, and the only such divergence
left in the gen-2 chain.

  +-2 g   1670.703  -> 1671.665922915
  +-4 g   835.3517  -> 835.832961457
  +-8 g   417.6759  -> 417.916480729
  +-16 g  208.8379  -> 208.958240364

Worth being explicit that the old values were not a mistake, and this is not a
correctness fix. Checked against ST's own vendored driver (lsm6dsv_reg.c):
every printed accel figure - 0.061 / 0.122 / 0.244 / 0.488 mg/LSB - is exactly
32768/FS rounded to three significant figures, because the accel really does
span the full 16-bit range at nominal full scale. So the derived form was the
more precise of the two, and moving to the datasheet figure trades a little
accuracy for agreement.

Agreement is worth more here. The firmware seeds these values into the on-device
calibration blob, so they are what the device reports and what becomes the
source of truth once per-unit calibration is honoured; keeping the exact form
would leave a 0.0576% step change in calibrated output waiting to surface on
that day. 0.0576% is far inside per-unit sensitivity variation.

The gyro is a genuinely different case and is deliberately left alone: 4.375
mdps/LSB implies a real full scale of 143.4 dps on the +-125 dps setting, which
is where the part is observed to saturate, so there a 32768/FS derivation is
wrong by ~14.7% rather than by a rounding. The comment now spells out the
distinction so the two are not "fixed" to match each other later.

API_00008 CAL locks updated (accel +-4 g literal); 51 driver tests pass.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Author: marknolan

ShimmerDriver/src/main/java/com/shimmerresearch/verisense/sensors/SensorLSM6DSV.java

@@ -41,7 +41,7 @@
  * {@code VerisenseDevice.parseDataBlockDataLsm6dsv(...)}. This class provides the
  * channel definitions, configuration and calibration.
  * <p>
- * Sensitivities: 32768/(FS*9.80665) LSB per m/s^2 for accel, the ST angular-rate
+ * Sensitivities: the ST datasheet nominal for every axis - 0.061 mg/LSB at +-2 g
  * spec of 4.375 mdps/LSB at +-125 dps for gyro, and 667 LSB/Gauss for the LIS2MDL
  * mag - the last taken from {@link SensorLIS2MDL} rather than duplicated here, so
  * calibrated magnetometer output is in GAUSS, consistent with every other Shimmer
@@ -285,16 +285,38 @@ public static final class DatabaseConfigHandle {
 	 * det +1 and computes canonical 0.0 entries, so it stays derived.) */
 	public static final double[][] DEFAULT_ALIGNMENT_LIS2MDL_MAG = {{1,0,0},{0,0,1},{0,1,0}};
 
-	// Accel sensitivity (LSB per m/s^2) = 32768/(FS_g*9.80665)
-	public static final double[][] SENS_ACCEL_2G  = {{1670.703,0,0},{0,1670.703,0},{0,0,1670.703}};
-	public static final double[][] SENS_ACCEL_4G  = {{835.3517,0,0},{0,835.3517,0},{0,0,835.3517}};
-	public static final double[][] SENS_ACCEL_8G  = {{417.6759,0,0},{0,417.6759,0},{0,0,417.6759}};
-	public static final double[][] SENS_ACCEL_16G = {{208.8379,0,0},{0,208.8379,0},{0,0,208.8379}};
+	// Accel sensitivity (LSB per m/s^2) from the ST datasheet linear-acceleration
+	// sensitivity: 0.061 / 0.122 / 0.244 / 0.488 mg/LSB, i.e. 1/(mg_per_LSB/1000)/9.80665.
+	//
+	// These were previously derived as 32768/(FS_g*9.80665), which is the exact form:
+	// unlike the gyro (see below) the accel really does span the full 16-bit range at
+	// its nominal full scale, so ST's printed figures are just 32768/FS rounded to
+	// three significant figures (2/32768 g = 0.06103516 mg/LSB -> "0.061"). The exact
+	// derivation is therefore 0.0576% larger and, on its own terms, slightly more
+	// accurate.
+	//
+	// We use the datasheet figures anyway, for agreement rather than precision. The
+	// firmware seeds these exact values into the on-device calibration blob
+	// (SC_ACCEL_SENS in asm_calibration.c), so they are what the device itself
+	// reports and what becomes the source of truth once per-unit calibration is
+	// loaded; the web SDK catalog and the gen-1 SensorLSM6DS3/SensorLIS2DW12 classes
+	// use them too, as does ST's own reference driver (lsm6dsv_from_fs2_to_mg
+	// multiplies by 0.061f). Keeping the exact form here would leave a 0.0576% step
+	// change in calibrated output waiting to appear the day the device blob is
+	// honoured. 0.0576% is far inside per-unit sensitivity variation, so consistency
+	// is worth more than the last digit.
+	public static final double[][] SENS_ACCEL_2G  = {{1671.665922915,0,0},{0,1671.665922915,0},{0,0,1671.665922915}};
+	public static final double[][] SENS_ACCEL_4G  = {{835.832961457,0,0},{0,835.832961457,0},{0,0,835.832961457}};
+	public static final double[][] SENS_ACCEL_8G  = {{417.916480729,0,0},{0,417.916480729,0},{0,0,417.916480729}};
+	public static final double[][] SENS_ACCEL_16G = {{208.958240364,0,0},{0,208.958240364,0},{0,0,208.958240364}};
 
 	// Gyro sensitivity (LSB per dps) from the ST datasheet angular-rate sensitivity
 	// (4.375 mdps/LSB at +-125 dps, doubling per range) - the same spec/values as the
-	// gen-1 LSM6DS3. NOTE: the gyro does NOT span the full 16-bit range at its nominal
-	// full scale (unlike the accel), so a 32768/FS derivation is ~12.8% off.
+	// gen-1 LSM6DS3. NOTE: unlike the accel above, the gyro genuinely does NOT span
+	// the full 16-bit range at its nominal full scale - 4.375 mdps/LSB implies a real
+	// full scale of 143.4 dps for the +-125 dps setting, which is exactly where the
+	// part is observed to saturate - so here a 32768/FS derivation is not a rounding
+	// difference but plainly wrong (~14.7%).
 	public static final double[][] SENS_GYRO_125DPS  = {{228.571428571,0,0},{0,228.571428571,0},{0,0,228.571428571}};
 	public static final double[][] SENS_GYRO_250DPS  = {{114.285714286,0,0},{0,114.285714286,0},{0,0,114.285714286}};
 	public static final double[][] SENS_GYRO_500DPS  = {{57.142857143,0,0},{0,57.142857143,0},{0,0,57.142857143}};

ShimmerDriver/src/test/java/com/shimmerresearch/verisense/API_00008_VerisenseLsm6dsvTaggedFifoParsing.java

@@ -142,14 +142,16 @@ public void test001_accelGyroMagInterleaved() throws Exception {
 		// CAL assertions - regression-locks the calibration constants against
 		// LITERAL expected values (the gyro sensitivity was ~12.8% wrong before the
 		// DEV-793 round-2 review fix; deriving the expectation from the class
-		// constants would defeat the lock). Defaults: accel +/-4 g = 835.3517
-		// LSB/(m/s^2); gyro +/-500 dps = 57.142857 LSB/dps (ST 17.50 mdps/LSB);
+		// constants would defeat the lock). Defaults: accel +/-4 g = 835.832961457
+		// LSB/(m/s^2) (ST 0.122 mg/LSB - see the sensitivity note in SensorLSM6DSV
+		// for why the datasheet figure is used and not the exact 32768/FS form);
+		// gyro +/-500 dps = 57.142857 LSB/dps (ST 17.50 mdps/LSB);
 		// mag 667 LSB/Gauss (LIS2MDL 1.5 mGauss/LSB, legacy rounding of 666.67).
 		// Since DEV-922 the defaults also apply the gen-2 sensor->ASM alignment:
 		// accel/gyro calibrated X/Y/Z come from raw Y/Z/X, mag X/Y/Z from raw X/Z/Y.
-		assertEquals(-200 / 835.3517, cal(aligned0, SensorLSM6DSV.ObjectClusterSensorName.LSM6DSV_ACC_X), 0.0001);
-		assertEquals(300 / 835.3517, cal(aligned0, SensorLSM6DSV.ObjectClusterSensorName.LSM6DSV_ACC_Y), 0.0001);
-		assertEquals(100 / 835.3517, cal(aligned0, SensorLSM6DSV.ObjectClusterSensorName.LSM6DSV_ACC_Z), 0.0001);
+		assertEquals(-200 / 835.832961457, cal(aligned0, SensorLSM6DSV.ObjectClusterSensorName.LSM6DSV_ACC_X), 0.0001);
+		assertEquals(300 / 835.832961457, cal(aligned0, SensorLSM6DSV.ObjectClusterSensorName.LSM6DSV_ACC_Y), 0.0001);
+		assertEquals(100 / 835.832961457, cal(aligned0, SensorLSM6DSV.ObjectClusterSensorName.LSM6DSV_ACC_Z), 0.0001);
 		assertEquals(-20 / 57.142857143, cal(aligned0, SensorLSM6DSV.ObjectClusterSensorName.LSM6DSV_GYRO_X), 0.0001);
 		assertEquals(30 / 57.142857143, cal(aligned0, SensorLSM6DSV.ObjectClusterSensorName.LSM6DSV_GYRO_Y), 0.0001);
 		assertEquals(10 / 57.142857143, cal(aligned0, SensorLSM6DSV.ObjectClusterSensorName.LSM6DSV_GYRO_Z), 0.0001);