FIX: Bug where ganglion channel data with no scale returned array of 8 instead of 4

Author: AJ Keller

Diff for: changelog.md

@@ -4,6 +4,10 @@
 
 * Add new constants for emitter
 
+### Bug Fixes
+
+* Fix bug where ganglion sample channel data when scale was false produced array of 8 values instead of 4
+
 # v0.2.3
 
 ### New Features

Diff for: openBCIUtilities.js

@@ -1118,7 +1118,7 @@ function parsePacketStandardAccel (o) {
   else sampleObject.accelDataCounts = getDataArrayAccelNoScale(o.rawDataPacket.slice(k.OBCIPacketPositionStartAux, k.OBCIPacketPositionStopAux + 1));
 
   if (o.scale) sampleObject.channelData = getChannelDataArray(o);
-  else sampleObject.channelDataCounts = getChannelDataArrayNoScale(o.rawDataPacket);
+  else sampleObject.channelDataCounts = getChannelDataArrayNoScale(o);
 
   if (k.getVersionNumber(process.version) >= 6) {
     // From introduced in node version 6.x.x
@@ -1165,7 +1165,7 @@ function parsePacketStandardRawAux (o) {
   // Store the channel data
   if (k.isUndefined(o.scale) || k.isNull(o.scale)) o.scale = true;
   if (o.scale) sampleObject.channelData = getChannelDataArray(o);
-  else sampleObject.channelDataCounts = getChannelDataArrayNoScale(o.rawDataPacket);
+  else sampleObject.channelDataCounts = getChannelDataArrayNoScale(o);
 
   // Slice the buffer for the aux data
   if (k.getVersionNumber(process.version) >= 6) {
@@ -1237,7 +1237,7 @@ function parsePacketTimeSyncedAccel (o) {
 
   if (k.isUndefined(o.scale) || k.isNull(o.scale)) o.scale = true;
   if (o.scale) sampleObject.channelData = getChannelDataArray(o);
-  else sampleObject.channelDataCounts = getChannelDataArrayNoScale(o.rawDataPacket);
+  else sampleObject.channelDataCounts = getChannelDataArrayNoScale(o);
 
   // Grab the accelData only if `getFromTimePacketAccel` returns true.
   if (getFromTimePacketAccel(o)) {
@@ -1296,7 +1296,7 @@ function parsePacketTimeSyncedRawAux (o) {
   // Grab the channel data.
   if (k.isUndefined(o.scale) || k.isNull(o.scale)) o.scale = true;
   if (o.scale) sampleObject.channelData = getChannelDataArray(o);
-  else sampleObject.channelDataCounts = getChannelDataArrayNoScale(o.rawDataPacket);
+  else sampleObject.channelDataCounts = getChannelDataArrayNoScale(o);
 
   sampleObject.valid = true;
 
@@ -1637,19 +1637,28 @@ function getChannelDataArray (o) {
 }
 
 /**
- * @description Takes a buffer filled with 24 bit signed integers from an OpenBCI device with gain settings in
- *                  channelSettingsArray[index].gain and converts based on settings of ADS1299... spits out an
- *                  array of floats in VOLTS
- * @param dataBuf {Buffer} - Buffer with 33 bit signed integers, number of elements is same as channelSettingsArray.length * 3
+ * @description Takes a buffer filled with 24 bit signed integers from an OpenBCI device converts to array of counts
+ * @param o {Object} - The input object
+ * @param o.rawDataPacket {Buffer} - The 33byte raw time synced accel packet
+ * @param o.channelSettings {Array} - An array of channel settings that is an Array that has shape similar to the one
+ *                  calling k.channelSettingsArrayInit(). The most important rule here is that it is
+ *                  Array of objects that have key-value pair {gain:NUMBER}
  * @returns {Array} - Array filled with floats for each channel's voltage in VOLTS
  * @author AJ Keller (@aj-ptw)
  */
-function getChannelDataArrayNoScale (dataBuf) {
+function getChannelDataArrayNoScale (o) {
+  if (!Array.isArray(o.channelSettings)) {
+    throw new Error('Error [getChannelDataArrayNoScale]: Channel Settings must be an array!');
+  }
   let channelData = [];
-  // Channel data arrays are always 8 long
-  for (let i = 0; i < k.OBCINumberOfChannelsDefault; i++) {
+  let numChannels = o.channelSettings.length;
+  if (numChannels > k.OBCINumberOfChannelsDefault) {
+    numChannels = k.OBCINumberOfChannelsDefault;
+  }
+  // Channel data arrays cannot be more than 8
+  for (let i = 0; i < numChannels; i++) {
     // Convert the three byte signed integer and convert it
-    channelData.push(utilitiesModule.interpret24bitAsInt32(dataBuf.slice((i * 3) + k.OBCIPacketPositionChannelDataStart, (i * 3) + k.OBCIPacketPositionChannelDataStart + 3)));
+    channelData.push(utilitiesModule.interpret24bitAsInt32(o.rawDataPacket.slice((i * 3) + k.OBCIPacketPositionChannelDataStart, (i * 3) + k.OBCIPacketPositionChannelDataStart + 3)));
   }
   return channelData;
 }

Diff for: package.json

@@ -1,6 +1,6 @@
 {
   "name": "openbci-utilities",
-  "version": "0.2.3",
+  "version": "0.2.4",
   "description": "The official utility package of Node.js SDK for the OpenBCI Biosensor Boards.",
   "main": "index.js",
   "scripts": {

Diff for: test/openBCIUtilities-test.js

@@ -1135,6 +1135,7 @@ describe('openBCIUtilities', function () {
     it('without scale all the channels should have the same number value as their (index + 1)', function () {
       packet = openBCIUtilities.samplePacketRawAuxTimeSynced(0);
       let sample = openBCIUtilities.parsePacketTimeSyncedRawAux({
+        channelSettings: defaultChannelSettingsArray,
         rawDataPacket: packet,
         timeOffset: 0,
         scale: false
@@ -1375,6 +1376,7 @@ describe('openBCIUtilities', function () {
     });
     it('should get raw aux buffer', function () {
       let sample = openBCIUtilities.parsePacketTimeSyncedRawAux({
+        channelSettings: defaultChannelSettingsArray,
         rawDataPacket: packetBuffer,
         timeOffset: 0,
         scale: false
@@ -1384,6 +1386,7 @@ describe('openBCIUtilities', function () {
     });
     it('should get board time', function () {
       let sample = openBCIUtilities.parsePacketTimeSyncedRawAux({
+        channelSettings: defaultChannelSettingsArray,
         rawDataPacket: packetBuffer,
         timeOffset: 0,
         scale: false
@@ -1394,6 +1397,7 @@ describe('openBCIUtilities', function () {
     it('should get time stamp with offset', function () {
       let timeOffset = 80;
       let sample = openBCIUtilities.parsePacketTimeSyncedRawAux({
+        channelSettings: defaultChannelSettingsArray,
         rawDataPacket: packetBuffer,
         timeOffset: timeOffset,
         scale: false
@@ -1755,6 +1759,46 @@ describe('openBCIUtilities', function () {
       expect(openBCIUtilities.isOdd(2)).to.be.false();
     });
   });
+  describe('#getChannelDataArrayNoScale', function () {
+    let sampleBuf;
+    beforeEach(() => {
+      sampleBuf = openBCIUtilities.samplePacket(0);
+    });
+    it('should return length of channel settings when less then 8', function () {
+      let numChannels = 2;
+      let channelSettings = k.channelSettingsArrayInit(numChannels);
+      let valArray = openBCIUtilities.getChannelDataArrayNoScale({
+        channelSettings: channelSettings,
+        rawDataPacket: sampleBuf
+      });
+      expect(valArray).to.have.length(numChannels);
+    });
+    it('should return length of channel settings of 8 when cyton', function () {
+      let numChannels = k.OBCINumberOfChannelsCyton;
+      let channelSettings = k.channelSettingsArrayInit(numChannels);
+      let valArray = openBCIUtilities.getChannelDataArrayNoScale({
+        channelSettings,
+        rawDataPacket: sampleBuf
+      });
+      expect(valArray).to.have.length(k.OBCINumberOfChannelsDefault);
+    });
+    it('should return length of channel settings of 8 when daisy', function () {
+      let numChannels = k.OBCINumberOfChannelsDaisy;
+      let channelSettings = k.channelSettingsArrayInit(numChannels);
+      let valArray = openBCIUtilities.getChannelDataArrayNoScale({
+        channelSettings,
+        rawDataPacket: sampleBuf
+      });
+      expect(valArray).to.have.length(k.OBCINumberOfChannelsDefault);
+    });
+    it('should reject when channelSettingsArray is not in fact an array', function () {
+      expect(openBCIUtilities.getChannelDataArrayNoScale.bind(openBCIUtilities, {
+        rawDataPacket: sampleBuf,
+        channelSettings: {},
+        protocol: k.OBCIProtocolWifi
+      })).to.throw('Error [getChannelDataArrayNoScale]: Channel Settings must be an array!');
+    });
+  });
   describe('#getChannelDataArray', function () {
     let sampleBuf, badChanArray;
     beforeEach(() => {
@@ -1878,20 +1922,6 @@ describe('openBCIUtilities', function () {
       });
     });
     describe('Wifi', function () {
-      it('should multiply each channel by the ganglion scale value when num chan is 4', function () {
-        let chanArr = k.channelSettingsArrayInit(k.OBCINumberOfChannelsGanglion); // Not in daisy mode
-        let scaleFactor = 1.2 / 51.0 / (Math.pow(2, 23) - 1);
-        // Call the function under test
-        let valueArray = openBCIUtilities.getChannelDataArray({
-          rawDataPacket: sampleBuf,
-          channelSettings: chanArr,
-          protocol: k.OBCIProtocolWifi
-        });
-        for (let j = 0; j < k.OBCINumberOfChannelsGanglion; j++) {
-          // console.log(`channel data ${j + 1}: ${valueArray[j]} : actual ${scaleFactor * (j + 1)}`);
-          expect(valueArray[j]).to.be.closeTo(scaleFactor * (j + 1), 0.0001);
-        }
-      });
       it('should multiply each channel by the cyton scale value when num chan is 8', function () {
         let chanArr = k.channelSettingsArrayInit(k.OBCINumberOfChannelsDefault); // Not in daisy mode
         let scaleFactor = 4.5 / 24 / (Math.pow(2, 23) - 1);