Index: firmware/App/Controllers/LoadCell.c
===================================================================
diff -u -r85b81717a743d9a805d249dbb10f58253410f00c -r849d55bf09a76e59424878b1ae4dac4b51ead3a9
--- firmware/App/Controllers/LoadCell.c	(.../LoadCell.c)	(revision 85b81717a743d9a805d249dbb10f58253410f00c)
+++ firmware/App/Controllers/LoadCell.c	(.../LoadCell.c)	(revision 849d55bf09a76e59424878b1ae4dac4b51ead3a9)
@@ -8,7 +8,7 @@
 * @file    LoadCell.c
 *
 * @author  (last)      Dara Navaei
-* @date    (last)      02-May-2022
+* @date    (last)      03-Aug-2022
 *
 * @author  (original)  Saeed Nejatali
 * @date    (original)  25-Feb-2020
@@ -170,10 +170,10 @@
     loadcells[ LOAD_CELL_RESERVOIR_2_BACKUP ].rawReading  = b2 & MASK_OFF_U32_MSB;
 
     // Check error bits from new readings
-    a1 = ( a1 >> 31 ) << SHIFT_24_BITS;
-    a2 = ( a2 >> 31 ) << SHIFT_16_BITS_FOR_WORD_SHIFT;
-    b1 = ( b1 >> 31 ) << SHIFT_8_BITS_FOR_BYTE_SHIFT;
-    b2 = ( b2 >> 31 );
+    a1 = ( a1 >> SHIFT_BITS_BY_31 ) << SHIFT_24_BITS;
+    a2 = ( a2 >> SHIFT_BITS_BY_31 ) << SHIFT_16_BITS_FOR_WORD_SHIFT;
+    b1 = ( b1 >> SHIFT_BITS_BY_31 ) << SHIFT_8_BITS_FOR_BYTE_SHIFT;
+    b2 = ( b2 >> SHIFT_BITS_BY_31 );
     if ( TRUE == isPersistentAlarmTriggered( ALARM_ID_DG_LOAD_CELL_ADC_ERROR, ( ( a1 > 0 ) || ( a2 > 0 ) || ( b1 > 0 ) || ( b2 > 0 ) ) ) )
     {
         SET_ALARM_WITH_1_U32_DATA( ALARM_ID_DG_LOAD_CELL_ADC_ERROR, ( a1 | a2 | b1 | b2 ) )
@@ -277,7 +277,7 @@
     SELF_TEST_STATUS_T result = SELF_TEST_STATUS_IN_PROGRESS;
 
     BOOL calStatus = getNVRecord2Driver( GET_CAL_LOAD_CELL_SENSORS, (U08*)&loadCellsCalRecord, sizeof( DG_LOAD_CELLS_CAL_RECORD_T ),
-                                                  NUM_OF_CAL_DATA_LOAD_CELLS, ALARM_ID_DG_LOAD_CELLS_INVALID_CAL_RECORD );
+                                         NUM_OF_CAL_DATA_LOAD_CELLS, ALARM_ID_DG_LOAD_CELLS_INVALID_CAL_RECORD );
 
     if ( TRUE == calStatus )
     {
@@ -293,6 +293,29 @@
 
 /*********************************************************************//**
  * @brief
+ * The isLoadCellTared function returns load cell tare status
+ * for a given load cell ID.
+ * @details Inputs: none
+ * @details Outputs: load cell tare status
+ * @param loadCellID ID of load cell tare status
+ *************************************************************************/
+BOOL isLoadCellTared( LOAD_CELL_ID_T loadCellID )
+{
+    BOOL tared = FALSE;
+
+    if ( fabs( loadcells[ loadCellID ].autoCalOffset ) < NEARLY_ZERO )
+    {
+        tared = FALSE;
+    }
+    else
+    {
+        tared = TRUE;
+    }
+    return tared;
+}
+
+/*********************************************************************//**
+ * @brief
  * The tareLoadCell function sets the load cell auto calibration offset
  * for a given load cell ID.
  * @details Inputs: none
@@ -302,9 +325,8 @@
 void tareLoadCell( LOAD_CELL_ID_T loadCellID )
 {
     BOOL isWeightOutOfRange = FALSE;
+    F32 weight              = getLoadCellSmallFilteredWeight( loadCellID );
 
-    F32 weight = getLoadCellSmallFilteredWeight( loadCellID );
-
     // Check if the load cell is being tared for the first time
     if ( hasLoadCellBeenTared[ loadCellID ] != TRUE )
     {
@@ -474,31 +496,38 @@
  *************************************************************************/
 static void monitorLoadCellsPrimaryBackupDriftOutOfRange( void )
 {
-    // TODO do we need this function at all?
-    F32 drift;
+    F32 drift = 0.0;
+    F32 loadCellADrift = 0.0;
+    F32 loadCellBDrift = 0.0;
+    BOOL isDriftOutOfRange = FALSE;
 
-    F32 loadCellADrift = fabs( getLoadCellSmallFilteredWeight( LOAD_CELL_RESERVOIR_1_PRIMARY ) -
+    // Test is valid after load cells are tared
+    if ( isLoadCellTared( LOAD_CELL_RESERVOIR_1_PRIMARY ) && isLoadCellTared( LOAD_CELL_RESERVOIR_1_BACKUP ) )
+    {
+        loadCellADrift = fabs( getLoadCellSmallFilteredWeight( LOAD_CELL_RESERVOIR_1_PRIMARY ) -
                                getLoadCellSmallFilteredWeight( LOAD_CELL_RESERVOIR_1_BACKUP ) );
-
-    F32 loadCellBDrift = fabs( getLoadCellSmallFilteredWeight( LOAD_CELL_RESERVOIR_2_PRIMARY ) -
+    }
+    if ( isLoadCellTared( LOAD_CELL_RESERVOIR_2_PRIMARY ) && isLoadCellTared( LOAD_CELL_RESERVOIR_2_BACKUP ) )
+    {
+        loadCellBDrift = fabs( getLoadCellSmallFilteredWeight( LOAD_CELL_RESERVOIR_2_PRIMARY ) -
                                getLoadCellSmallFilteredWeight( LOAD_CELL_RESERVOIR_2_BACKUP ) );
+    }
 
-    BOOL isDriftOutOfRange = ( loadCellADrift > LOAD_CELL_PRIMARY_BACKUP_MAX_ALLOWED_DRIFT_GRAMS ) ||
-                             ( loadCellBDrift > LOAD_CELL_PRIMARY_BACKUP_MAX_ALLOWED_DRIFT_GRAMS );
-
-    if ( TRUE == isDriftOutOfRange )
+    if ( ( loadCellADrift > LOAD_CELL_PRIMARY_BACKUP_MAX_ALLOWED_DRIFT_GRAMS ) ||
+            ( loadCellBDrift > LOAD_CELL_PRIMARY_BACKUP_MAX_ALLOWED_DRIFT_GRAMS ) )
     {
+        isDriftOutOfRange = TRUE;
         drift = ( loadCellADrift > LOAD_CELL_PRIMARY_BACKUP_MAX_ALLOWED_DRIFT_GRAMS ? loadCellADrift : loadCellBDrift );
     }
     else
     {
+        isDriftOutOfRange = FALSE;
         // Pick the biggest drift in between the two load cells when none of the is above range
         drift = ( loadCellADrift > loadCellBDrift ? loadCellADrift : loadCellBDrift );
     }
 
-    // TODO this alarm is disabled until a better drift algorithm is figured out. Drift check might be removed from the load cells
-    //checkPersistentAlarm( ALARM_ID_DG_LOAD_CELL_PRIMARY_BACKUP_DRIFT_OUT_OF_RANGE, isDriftOutOfRange, drift,
-     //                     LOAD_CELL_PRIMARY_BACKUP_MAX_ALLOWED_DRIFT_GRAMS );
+    checkPersistentAlarm( ALARM_ID_DG_LOAD_CELL_PRIMARY_BACKUP_DRIFT_OUT_OF_RANGE, isDriftOutOfRange, drift,
+                          LOAD_CELL_PRIMARY_BACKUP_MAX_ALLOWED_DRIFT_GRAMS );
 }