Avoid using floating point in the heartbeat code

Prior work in 2015 in this repository (commit 1c8ae71 and 52f3151)
had removed all uses of floating point, saving the flash memory needed
for floating point software routines.

More recently, floating point is used if HEARTBEAT_SUPERVISION is
enabled. By making a few small changes and adjusting things to use
integer math, we can save 600+ bytes of flash.

This also removes the deprecated function `HsDeactivate` which isn't
called from anywhere.

firmware/open_evse/CHANGELOG

@@ -1,10 +1,11 @@
 Change Log
 
-202012 toofishes
+20201209 toofishes
 - various code size optimizations for a smaller binary
 - recode energy meter usage calculation for better accuracy using integer math
 - remove Time.h and Time.cpp libraries, not needed as we track time in other ways
 - remove SERIALCLI, it hasn't been maintained in years and is replaced by RAPI
+- avoid using floating point in heartbeat code to save 600+ bytes of Flash
 
 20201001 SCL
 - move MV_FOR_xx from EnergyMeter.h to openevse.h, and outside of KWH_RECORDING

firmware/open_evse/J1772EvseController.cpp

@@ -2039,7 +2039,7 @@ int J1772EVSEController::HsPulse() {
   int rc = 1;
   #ifdef DEBUG_HS
 	Serial.print(F("HsPulse called.  Time interval before reset: "));
-	Serial.println((unsigned long)((millis() - m_HsLastPulse)/1000.0));
+	Serial.println((millis() - m_HsLastPulse)/1000);
   #endif
   if ((m_HsTriggered == HS_MISSEDPULSE_NOACK)) { //We were in a state of missed pulse 
     rc = 1; //We have been triggered but have not been acknowledged.  Therfore respond with NK.
@@ -2050,13 +2050,12 @@ int J1772EVSEController::HsPulse() {
   m_HsLastPulse = millis(); //We just had a heartbeat so reset the HEARTBEAT SUPERVISION timeout interval;
   #ifdef DEBUG_HS
 	Serial.print(F("                 Time interval  after reset: "));
-	Serial.println((unsigned long)((millis() - m_HsLastPulse)/1000.0));
+	Serial.println((millis() - m_HsLastPulse)/1000);
   #endif
   return rc;
 }
 
 int J1772EVSEController::HsRestoreAmpacity() {
-  UNION4B u1,u2,u3,u4;
   #ifdef DEBUG_HS
 	Serial.println(F("HsRestoreAmpacity called"));
   #endif
@@ -2065,14 +2064,14 @@ int J1772EVSEController::HsRestoreAmpacity() {
     #ifdef DEBUG_HS
 	  Serial.println(F("HEARTBEAT_SUPERVISION was previously triggered - checking if OK to restore ampacity"));
     #endif
-    u3.u8 = g_EvseController.GetMaxCurrentCapacity();  //We get the ceiling for how high we can set ampacity
+    uint8_t maxCapacity = g_EvseController.GetMaxCurrentCapacity();  //We get the ceiling for how high we can set ampacity
     #ifdef TEMPERATURE_MONITORING
       if (!g_TempMonitor.OverTemperature()) { //We need to ensure that OverTemperature is not active before we raise current capacity
 	    #ifdef DEBUG_HS
 	      Serial.print(F("Not over temp - OK to restore ampacity to: "));
-		  Serial.println(u3.u8);
+		  Serial.println(maxCapacity);
         #endif
-        rc = g_EvseController.SetCurrentCapacity(u3.u8,1,1);  //We are not writing EEPROM, but we are setting current to maximum capacity
+        rc = g_EvseController.SetCurrentCapacity(maxCapacity,1,1);  //We are not writing EEPROM, but we are setting current to maximum capacity
       }
       else {
         #ifdef DEBUG_HS
@@ -2081,7 +2080,7 @@ int J1772EVSEController::HsRestoreAmpacity() {
         rc = 1;  //Fail.  Cannnot restore ampacity, as TEMPERATURE_MONITORING OverTemperature() is still in force 
       }
     #else // !TEMPERATURE_MONITORING
-      rc = g_EvseController.SetCurrentCapacity(u3.u8,1,1);   //Do not write this value to EEPROM
+      rc = g_EvseController.SetCurrentCapacity(maxCapacity,1,1);   //Do not write this value to EEPROM
     #endif // TEMPERATURE_MONITORING
   }
   else {
@@ -2091,9 +2090,9 @@ int J1772EVSEController::HsRestoreAmpacity() {
 }
 
 int J1772EVSEController::HsExpirationCheck() {
-  unsigned long sinceLastPulse = (unsigned long)((millis() - m_HsLastPulse)/1000.0); //convert ms to seconds
+  unsigned long sinceLastPulse = millis() - m_HsLastPulse;
   int rc=1;
-  if ((m_HsInterval != 0) && (sinceLastPulse > m_HsInterval)) { //HEARTBEAT_SUPERVISION is currently active and the Heartbeat interval has timed out
+  if (m_HsInterval != 0 && sinceLastPulse > (m_HsInterval * 1000)) { //HEARTBEAT_SUPERVISION is currently active and the Heartbeat interval has timed out
   	#ifdef DEBUG_HS
 	  Serial.println(F("HsExpirationCheck: Heartbeat timer expired account late or no pulse"));
 	#endif
@@ -2103,7 +2102,7 @@ int J1772EVSEController::HsExpirationCheck() {
 	  #endif
       rc=SetCurrentCapacity(m_IFallback,1,1);  //Drop the current, update the display, and do not write it to EEPROM 	  
     }
-	//m_HsInterval timed out, and as a result we may have to perturb the system ampacity setting.
+    //m_HsInterval timed out, and as a result we may have to perturb the system ampacity setting.
     //We flag that here by setting m_HsTriggered = HS_MISSEDPULSE_NOACK
     m_HsTriggered = HS_MISSEDPULSE_NOACK; //Flag the fact that HEARTBEAT_SUPERVISION had a missed pulse and report same when pulsed (via nack), until acknowledged
 	m_HsLastPulse = millis(); //Reset the timer so we don't check again until the next interval
@@ -2145,17 +2144,6 @@ int J1772EVSEController::HsAckMissedPulse(uint8_t ack) {
   return rc;
 }
 
-int J1772EVSEController::HsDeactivate() {   
-//DEPRECATED USE HeartbeatSupervision set to 0 interval instead so update EEPROM!
-  #ifdef DEBUG_HS
-    Serial.println(F("HsDeactivate called - BUT I AM DEPRECATED!"));
-  #endif
-  int rc=1;
-  m_HsInterval = 0;
-  rc=(int)m_HsInterval;
-  return rc;
-}
-
 int J1772EVSEController::GetHearbeatInterval() {
   return (int)m_HsInterval;
 }

firmware/open_evse/J1772EvseController.h

@@ -403,7 +403,6 @@ int HsPulse();
 int HsRestoreAmpacity();
 int HsExpirationCheck();
 int HsAckMissedPulse(uint8_t ack);
-int HsDeactivate();
 int GetHearbeatInterval();
 int GetHearbeatCurrent();
 int GetHearbeatTrigger();