Index: firmware/App/Controllers/BloodFlow.c
===================================================================
diff -u -rf8feb10a7e19e17148e4ce8b247316c9772d1753 -r5e77f78c5dee9dfb441bd5d2053f7f4ac50dc619
--- firmware/App/Controllers/BloodFlow.c	(.../BloodFlow.c)	(revision f8feb10a7e19e17148e4ce8b247316c9772d1753)
+++ firmware/App/Controllers/BloodFlow.c	(.../BloodFlow.c)	(revision 5e77f78c5dee9dfb441bd5d2053f7f4ac50dc619)
@@ -55,7 +55,8 @@
 
 #define BP_HOME_RATE                        100             ///< target pump speed (in estimate mL/min) for homing.
 #define BP_HOME_TIMEOUT_MS                  10000           ///< maximum time allowed for homing to complete (in ms).
-#define BP_SPEED_CALC_INTERVAL              ( MS_PER_SECOND / TASK_PRIORITY_INTERVAL )  ///< interval (ms/task time) at which the blood pump speed is calculated.
+#define BP_SPEED_CALC_INTERVAL              ( 40 / TASK_PRIORITY_INTERVAL )  ///< interval (ms/task time) at which the blood pump speed is calculated.
+#define BP_SPEED_CALC_BUFFER__LEN           25              ///< number of hall sensor counts kept in buffer to hold last 1 second of count data.
 #define BP_HALL_EDGE_COUNTS_PER_REV         48              ///< number of hall sensor edge counts per motor revolution.
 #define BP_MAX_ROTOR_SPEED_RPM              100.0           ///< maximum rotor speed allowed for blood pump.
 
@@ -150,9 +151,10 @@
 static BOOL bpStopAtHomePosition = FALSE;                                       ///< stop blood pump at next home position
 static U32 bpHomeStartTime = 0;                                                 ///< when did blood pump home command begin? (in ms)
 
-static U16 bpLastMotorHallSensorCount = 0;                                      ///< last hall sensor count for the blood pump motor
+static U16 bpLastMotorHallSensorCounts[ BP_SPEED_CALC_BUFFER__LEN ];            ///< last hall sensor count for the blood pump motor
+static U32 bpMotorSpeedCalcIdx = 0;                                             ///< index into 1 second buffer of motor speed hall sensor counts
 static MOTOR_DIR_T bpMotorDirectionFromHallSensors = MOTOR_DIR_FORWARD;         ///< pump direction according to hall sensor count
-static U32 bpMotorSpeedCalcTimerCtr = 0;                                        ///< counter determines interval for calculating blood pump motor speed from hall sensor count.
+static U32 bpMotorSpeedCalcTimerCtr = 0;                                        ///< counter determines interval for calculating blood pump motor speed from hall sensor count.
 
 static U32 errorBloodFlowVsMotorSpeedPersistTimerCtr = 0;                       ///< persistence timer counter for flow vs. motor speed error condition.
 static U32 errorBloodMotorOffPersistTimerCtr = 0;                               ///< persistence timer counter for motor off check error condition.
@@ -199,15 +201,22 @@
  * @return none
  *************************************************************************/
 void initBloodFlow( void )
-{
-    bpLastMotorHallSensorCount = getFPGABloodPumpHallSensorCount();
+{
+    U32 i;
 
     stopBloodPump();
     setBloodPumpDirection( MOTOR_DIR_FORWARD );
 
     // zero rolling flow average buffer
     resetBloodFlowMovingAverage();
-
+
+    // zero motor hall sensors counts buffer
+    bpMotorSpeedCalcIdx = 0;
+    for ( i = 0; i < BP_SPEED_CALC_BUFFER__LEN; i++ )
+    {
+        bpLastMotorHallSensorCounts[ i ] = 0;
+    }
+
     // initialize blood flow PI controller
     initializePIController( PI_CONTROLLER_ID_BLOOD_FLOW, MIN_BLOOD_PUMP_PWM_DUTY_CYCLE,
                             BP_P_COEFFICIENT, BP_I_COEFFICIENT,
@@ -894,8 +903,9 @@
 {
     if ( ++bpMotorSpeedCalcTimerCtr >= BP_SPEED_CALC_INTERVAL )
     {
-        U16 bpMotorHallSensorCount = getFPGABloodPumpHallSensorCount();
-        U16 incDelta = ( bpMotorHallSensorCount >= bpLastMotorHallSensorCount ? bpMotorHallSensorCount - bpLastMotorHallSensorCount : ( HEX_64_K - bpLastMotorHallSensorCount ) + bpMotorHallSensorCount );
+        U16 bpMotorHallSensorCount = getFPGABloodPumpHallSensorCount();
+        U32 nextIdx = INC_WRAP( bpMotorSpeedCalcIdx, 0, BP_SPEED_CALC_BUFFER__LEN - 1 );
+        U16 incDelta = ( bpMotorHallSensorCount >= bpLastMotorHallSensorCounts[ nextIdx ] ? bpMotorHallSensorCount - bpLastMotorHallSensorCounts[ nextIdx ] : ( HEX_64_K - bpLastMotorHallSensorCounts[ nextIdx ] ) + bpMotorHallSensorCount );
         U16 decDelta = HEX_64_K - incDelta;
         U16 delta;
 
@@ -914,7 +924,8 @@
         }
 
         // update last count for next time
-        bpLastMotorHallSensorCount = bpMotorHallSensorCount;
+        bpLastMotorHallSensorCounts[ nextIdx ] = bpMotorHallSensorCount;
+        bpMotorSpeedCalcIdx = nextIdx;
         bpMotorSpeedCalcTimerCtr = 0;
     }
 }