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Update of the BITalino sensors transfer functions (according to PLUX datasheets) #6

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f8b5927
Update of the BITalino sensors transfer functions (according to PLUX …
GRamosPlux Aug 24, 2021
3e9a7a4
Update of the BITalino Respiration Sensor Transfer Function
GRamosPlux Aug 26, 2021
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112 changes: 69 additions & 43 deletions src/main/java/com/bitalino/util/SensorDataConverter.java
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Original file line number Diff line number Diff line change
Expand Up @@ -26,6 +26,7 @@

import java.math.BigDecimal;
import java.math.RoundingMode;
import java.util.Arrays;

/**
* This class holds methods for converting/scaling raw data from BITalino
Expand All @@ -34,20 +35,27 @@
public class SensorDataConverter {

private static final double VCC = 3.3; // volts
private static final int ACC_MIN = 185;
private static final int ACC_MAX = 275;
private static final int NBR_BITALINO_CHANNELS = 6;
private static final int EMG_GAIN = 1009;
private static final int ECG_GAIN = 1100;
private static final double EDA_SCALE_FACTOR = 0.132;
private static final int EEG_GAIN = 41782;

/**
* ElectroMyoGraphy conversion.
*
* @param port
* the port where the <tt>raw</tt> value was read from.
* @param activePorts
* array containing the list of active <tt>ports</tt>, for example, when the 6
* available ports are active the array should be {0, 1, 2, 3, 4, 5}.
* @param raw
* the value read.
* @return a value ranging between -1.65 and 1.65mV
* @return a value ranging between -1.64 and 1.64mV
*/
public static double scaleEMG(final int port, final int raw) {
final double result = (raw * VCC / getResolution(port) - VCC / 2);
public static double scaleEMG(final int port, final Integer[] activePorts, final int raw) {
final double result =
((raw * VCC / getResolution(port, activePorts) - VCC / 2) * 1000) / EMG_GAIN;
return new BigDecimal(result).setScale(2, RoundingMode.HALF_UP)
.doubleValue();
}
Expand All @@ -57,31 +65,36 @@ public static double scaleEMG(final int port, final int raw) {
*
* @param port
* the port where the <tt>raw</tt> value was read from.
* @param activePorts
* array containing the list of active <tt>ports</tt>, for example, when the 6
* available ports are active the array should be {0, 1, 2, 3, 4, 5}.
* @param raw
* the value read.
* @return a value ranging between -1.5 and 1.5mV
*/
public static double scaleECG(final int port, final int raw) {
final double result = (((raw / getResolution(port) -0.5)*VCC) / 1100) * 1000;
public static double scaleECG(final int port, final Integer[] activePorts, final int raw) {
final double result = (((raw / getResolution(port, activePorts) - 0.5) * VCC) / ECG_GAIN) * 1000;
return new BigDecimal(result).setScale(2, RoundingMode.HALF_UP)
.doubleValue();
}

/**
* Accelerometer conversion based on reference calibration values. If you want
* to acquire more precise values, use
* {@link #scaleAccelerometerWithPrecision(int, int, int, int)
* {@link #scaleAccelerometerWithPrecision(int, Integer[], int)
* scaleAccelerometerWithPrecision} method.
*
* @param port
* the port where the <tt>raw</tt> value was read from.
* @param activePorts
* array containing the list of active <tt>ports</tt>, for example, when the 6
* available ports are active the array should be {0, 1, 2, 3, 4, 5}.
* @param raw
* the value read.
* @return a value ranging between -5 and 4.5Gs
* @return a value ranging between -4.85 and 4.85g (6 bits) or between -4.85 and 4.99 (10 bits).
*/
public static double scaleAccelerometer(final int port, final int raw) {
final double result = scaleAccelerometerWithPrecision(port, raw, ACC_MIN,
ACC_MAX);
public static double scaleAccelerometer(final int port, final Integer[] activePorts, final int raw) {
final double result = scaleAccelerometerWithPrecision(port, activePorts, raw);
return new BigDecimal(result).setScale(2, RoundingMode.HALF_UP)
.doubleValue();
}
Expand All @@ -91,16 +104,17 @@ public static double scaleAccelerometer(final int port, final int raw) {
*
* @param port
* the port where the <tt>raw</tt> value was read from.
* @param activePorts
* array containing the list of active <tt>ports</tt>, for example, when the 6
* available ports are active the array should be {0, 1, 2, 3, 4, 5}.
* @param raw
* the value read.
* @param min
* the calibration minimum value
* @param max
* the calibration maximum value
* @return a value ranging between -3 and 3Gs
* @return a value ranging between -4.85 and 4.85g (6 bits) or between -4.85 and 4.99 (10 bits).
*/
public static double scaleAccelerometerWithPrecision(final int port,
final int raw, final int min, final int max) {
public static double scaleAccelerometerWithPrecision(final int port, final Integer[] activePorts,
final int raw) {
int min = getResolution(port, activePorts) == 1023 ? 400 : 25;
int max = getResolution(port, activePorts) == 1023 ? 608 : 38;
return 2 * ((double)(raw - min) / (max - min)) - 1;
}

Expand All @@ -109,48 +123,52 @@ public static double scaleAccelerometerWithPrecision(final int port,
*
* @param port
* the port where the <tt>raw</tt> value was read from.
* @param activePorts
* array containing the list of active <tt>ports</tt>, for example, when the 6
* available ports are active the array should be {0, 1, 2, 3, 4, 5}.
* @param raw
* the value read.
* @return a value ranging from 1 and inf uS (micro Siemens),
* beware might return Double.POSITIVE_INFINITY
* @return a value ranging from 0 to 25 uS (micro Siemens).
*/
public static double scaleEDA(final int port, final int raw) {
// need to round maximum value that otherwise is 1.05496875
final double ohm = 1 - ( (double)raw /(double)1023);
double result = 1/ohm;
if (result != Double.POSITIVE_INFINITY)
result = new BigDecimal(result).setScale(4, RoundingMode.HALF_UP)
public static double scaleEDA(final int port, final Integer[] activePorts, final int raw) {
final double result = ((raw / getResolution(port, activePorts)) * VCC) / EDA_SCALE_FACTOR;
return new BigDecimal(result).setScale(2, RoundingMode.HALF_UP)
.doubleValue();
return result;
}

/**
* Luminosity conversion.
*
* @param port
* the port where the <tt>raw</tt> value was read from.
* @param activePorts
* array containing the list of active <tt>ports</tt>, for example, when the 6
* available ports are active the array should be {0, 1, 2, 3, 4, 5}.
* @param raw
* the value read.
* @return a value ranging from 0 and 100%.
*/
public static double scaleLuminosity(final int port, final int raw) {
return 100 * (raw / getResolution(port));
public static double scaleLuminosity(final int port, final Integer[] activePorts, final int raw) {
return 100 * (raw / getResolution(port, activePorts));
}

/**
* Temperature conversion.
*
* @param port
* the port where the <tt>raw</tt> value was read from.
* @param activePorts
* array containing the list of active <tt>ports</tt>, for example, when the 6
* available ports are active the array should be {0, 1, 2, 3, 4, 5}.
* @param raw
* the value read.
* @param celsius
* <tt>true</tt>:use celsius as metric,
* <tt>false</tt>: fahrenheit is used.
* @return a value ranging between -40 and 125 Celsius (-40 and 257 Fahrenheit)
* @return a value ranging between -50 and 280 Celsius (-58 and 536 Fahrenheit)
*/
public static double scaleTMP(final int port, final int raw, boolean celsius){
double result = (((raw/getResolution(port))*VCC) - 0.5)*100;
public static double scaleTMP(final int port, final Integer[] activePorts, final int raw, boolean celsius){
double result = (((raw/getResolution(port, activePorts))*VCC) - 0.5)*100;

if (!celsius)
// Convert to fahrenheit
Expand All @@ -165,12 +183,15 @@ public static double scaleTMP(final int port, final int raw, boolean celsius){
*
* @param port
* the port where the <tt>raw</tt> value was read from.
* @param activePorts
* array containing the list of active <tt>ports</tt>, for example, when the 6
* available ports are active the array should be {0, 1, 2, 3, 4, 5}.
* @param raw
* the value read.
* @return a value ranging between -50% and 50%
* @return a value ranging between -1.65V and 1.65V
*/
public static double scalePZT(final int port, final int raw){
double result = ((raw/getResolution(port)) - 0.5)*100;
public static double scalePZT(final int port, final Integer[] activePorts, final int raw){
double result = ((raw/getResolution(port, activePorts)) - 0.5)*VCC;
return new BigDecimal(result).setScale(2, RoundingMode.HALF_UP)
.doubleValue();

Expand All @@ -181,15 +202,16 @@ public static double scalePZT(final int port, final int raw){
*
* @param port
* the port where the <tt>raw</tt> value was read from.
* @param activePorts
* array containing the list of active <tt>ports</tt>, for example, when the 6
* available ports are active the array should be {0, 1, 2, 3, 4, 5}.
* @param raw
* the value read.
* @return a value ranging between -41.5 and 41.5 microvolt
* @return a value ranging between -39.49 and 39.49 microvolt
*/
public static double scaleEEG(final int port, final int raw){
double G_ECG = 40000; // sensor gain

public static double scaleEEG(final int port, final Integer[] activePorts, final int raw){
// result rescaled to microvolt
double result = (((raw/getResolution(port))-0.5)*VCC)/G_ECG;
double result = (((raw/getResolution(port, activePorts))-0.5)*VCC)/EEG_GAIN;
result = result*Math.pow(10, 6);

return new BigDecimal(result).setScale(2, RoundingMode.HALF_UP)
Expand All @@ -203,10 +225,14 @@ public static double scaleEEG(final int port, final int raw){
* From port 4 to 5, the resolution is 6-bit, thus 2^6 - 1 = 63.
*
* @param port
* index of the port under analysis.
* @param activePorts
* array containing the list of active <tt>ports</tt>, for example, when the 6
* available ports are active the array should be {0, 1, 2, 3, 4, 5}.
* @return the resolution (maximum value) for a certain port.
*/
private static final double getResolution(final int port) {
return (double) port < 4 ? 1023 : 63;
private static final double getResolution(final int port, final Integer[] activePorts) {
return (double) activePorts.length > NBR_BITALINO_CHANNELS - 2 && Arrays.asList(activePorts).indexOf(port) < NBR_BITALINO_CHANNELS - 2 || activePorts.length <= NBR_BITALINO_CHANNELS - 2 ? 1023 : 63;
}

}
74 changes: 58 additions & 16 deletions src/test/java/com/bitalino/util/SensorDataConverterTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -32,50 +32,92 @@ public class SensorDataConverterTest {

@Test
public void test_emg_conversion() {
assertEquals(SensorDataConverter.scaleEMG(0, 0), -1.65);
assertEquals(SensorDataConverter.scaleEMG(0, 1023), 1.65);
assertEquals(SensorDataConverter.scaleEMG(0, new Integer[]{0}, 0), -1.64);
assertEquals(SensorDataConverter.scaleEMG(5, new Integer[]{1, 2, 3, 5}, 0), -1.64);
assertEquals(SensorDataConverter.scaleEMG(5, new Integer[]{0, 1, 2, 3, 5}, 0), -1.64);
assertEquals(SensorDataConverter.scaleEMG(5, new Integer[]{0, 1, 2, 3, 5}, 63),1.64);
assertEquals(SensorDataConverter.scaleEMG(3, new Integer[]{0, 1, 2, 3, 5},1023),1.64);
assertEquals(SensorDataConverter.scaleEMG(0, new Integer[]{0}, 1023),1.64);
}

@Test
public void test_ecg_conversion() {
assertEquals(SensorDataConverter.scaleECG(0, 0), -1.5);
assertEquals(SensorDataConverter.scaleECG(0, 1023), 1.5);
assertEquals(SensorDataConverter.scaleECG(0, new Integer[]{0}, 0), -1.5);
assertEquals(SensorDataConverter.scaleECG(5, new Integer[]{1, 2, 3, 5}, 0), -1.5);
assertEquals(SensorDataConverter.scaleECG(5, new Integer[]{0, 1, 2, 3, 5}, 0), -1.5);
assertEquals(SensorDataConverter.scaleECG(5, new Integer[]{0, 1, 2, 3, 5}, 63),1.5);
assertEquals(SensorDataConverter.scaleECG(3, new Integer[]{0, 1, 2, 3, 5},1023),1.5);
assertEquals(SensorDataConverter.scaleECG(0, new Integer[]{0}, 1023), 1.5);
}

@Test
public void test_acc_conversion() {
assertEquals(SensorDataConverter.scaleAccelerometer(0, new Integer[]{0}, 0), -4.85);
assertEquals(SensorDataConverter.scaleAccelerometer(5, new Integer[]{1, 2, 3, 5}, 0),-4.85);
assertEquals(SensorDataConverter.scaleAccelerometer(5, new Integer[]{0, 1, 2, 3, 5}, 0),-4.85);
assertEquals(SensorDataConverter.scaleAccelerometer(5, new Integer[]{0, 1, 2, 3, 5}, 63),4.85);
assertEquals(SensorDataConverter.scaleAccelerometer(3, new Integer[]{0, 1, 2, 3, 5},1023),4.99);
assertEquals(SensorDataConverter.scaleAccelerometer(0, new Integer[]{0}, 1023), 4.99);
}

@Test
public void test_eda_conversion() {
assertEquals(SensorDataConverter.scaleEDA(0, 0), 1.0);
assertEquals(SensorDataConverter.scaleEDA(0, 1023), Double.POSITIVE_INFINITY);
assertEquals(SensorDataConverter.scaleEDA(0, new Integer[]{0}, 0), 0.0);
assertEquals(SensorDataConverter.scaleEDA(5, new Integer[]{1, 2, 3, 5}, 0), 0.0);
assertEquals(SensorDataConverter.scaleEDA(5, new Integer[]{0, 1, 2, 3, 5}, 0), 0.0);
assertEquals(SensorDataConverter.scaleEDA(5, new Integer[]{0, 1, 2, 3, 5}, 63),25.0);
assertEquals(SensorDataConverter.scaleEDA(3, new Integer[]{0, 1, 2, 3, 5},1023),25.0);
assertEquals(SensorDataConverter.scaleEDA(0, new Integer[]{0}, 1023), 25.0);
}

@Test
public void test_luminosity_conversion() {
assertEquals(SensorDataConverter.scaleLuminosity(0, 0), 0.0);
assertEquals(SensorDataConverter.scaleLuminosity(0, 1023), 100.0);
assertEquals(SensorDataConverter.scaleLuminosity(0, new Integer[]{0}, 0), 0.0);
assertEquals(SensorDataConverter.scaleLuminosity(5, new Integer[]{1, 2, 3, 5}, 0), 0.0);
assertEquals(SensorDataConverter.scaleLuminosity(5, new Integer[]{0, 1, 2, 3, 5}, 0), 0.0);
assertEquals(SensorDataConverter.scaleLuminosity(5, new Integer[]{0, 1, 2, 3, 5}, 63),100.0);
assertEquals(SensorDataConverter.scaleLuminosity(3, new Integer[]{0, 1, 2, 3, 5},1023),100.0);
assertEquals(SensorDataConverter.scaleLuminosity(0, new Integer[]{0}, 1023), 100.0);
}

@Test
public void test_tmp_celsius_conversion() {
assertEquals(SensorDataConverter.scaleTMP(0, 0, true), -50.0);
assertEquals(SensorDataConverter.scaleTMP(0, 1023, true), 280.0);
assertEquals(SensorDataConverter.scaleTMP(0, new Integer[]{0}, 0, true), -50.0);
assertEquals(SensorDataConverter.scaleTMP(5, new Integer[]{1, 2, 3, 5}, 0, true), -50.0);
assertEquals(SensorDataConverter.scaleTMP(5, new Integer[]{0, 1, 2, 3, 5}, 0, true), -50.0);
assertEquals(SensorDataConverter.scaleTMP(5, new Integer[]{0, 1, 2, 3, 5}, 63, true),280.0);
assertEquals(SensorDataConverter.scaleTMP(3, new Integer[]{0, 1, 2, 3, 5},1023, true),280.0);
assertEquals(SensorDataConverter.scaleTMP(0, new Integer[]{0}, 1023, true), 280.0);
}

@Test
public void test_tmp_fahrenheit_conversion() {
assertEquals(SensorDataConverter.scaleTMP(0, 0, false), -58.0);
assertEquals(SensorDataConverter.scaleTMP(0, 1023, false), 536.0);
assertEquals(SensorDataConverter.scaleTMP(0, new Integer[]{0},0, false), -58.0);
assertEquals(SensorDataConverter.scaleTMP(5, new Integer[]{1, 2, 3, 5},0, false), -58.0);
assertEquals(SensorDataConverter.scaleTMP(5, new Integer[]{0, 1, 2, 3, 5},0, false), -58.0);
assertEquals(SensorDataConverter.scaleTMP(5, new Integer[]{0, 1, 2, 3, 5}, 63, false),536.0);
assertEquals(SensorDataConverter.scaleTMP(3, new Integer[]{0, 1, 2, 3, 5},1023, false),536.0);
assertEquals(SensorDataConverter.scaleTMP(0, new Integer[]{0},1023, false), 536.0);
}

@Test
public void test_pzt_conversion() {
assertEquals(SensorDataConverter.scalePZT(0, 0), -50.0);
assertEquals(SensorDataConverter.scalePZT(0, 1023), 50.0);
assertEquals(SensorDataConverter.scalePZT(0, new Integer[]{0},0), -1.65);
assertEquals(SensorDataConverter.scalePZT(5, new Integer[]{1, 2, 3, 5},0), -1.65);
assertEquals(SensorDataConverter.scalePZT(5, new Integer[]{0, 1, 2, 3, 5},0), -1.65);
assertEquals(SensorDataConverter.scalePZT(5, new Integer[]{0, 1, 2, 3, 5}, 63),1.65);
assertEquals(SensorDataConverter.scalePZT(3, new Integer[]{0, 1, 2, 3, 5},1023),1.65);
assertEquals(SensorDataConverter.scalePZT(0, new Integer[]{0},1023), 1.65);
}

@Test
public void test_EEG_conversion() {
assertEquals(SensorDataConverter.scaleEEG(0, 0), -41.25);
assertEquals(SensorDataConverter.scaleEEG(0, 1023), 41.25);
assertEquals(SensorDataConverter.scaleEEG(0, new Integer[]{0}, 0), -39.49);
assertEquals(SensorDataConverter.scaleEEG(5, new Integer[]{1, 2, 3, 5}, 0), -39.49);
assertEquals(SensorDataConverter.scaleEEG(5, new Integer[]{0, 1, 2, 3, 5}, 0), -39.49);
assertEquals(SensorDataConverter.scaleEEG(5, new Integer[]{0, 1, 2, 3, 5}, 63),39.49);
assertEquals(SensorDataConverter.scaleEEG(3, new Integer[]{0, 1, 2, 3, 5},1023),39.49);
assertEquals(SensorDataConverter.scaleEEG(0, new Integer[]{0}, 1023), 39.49);
}

}