From 17cc712326c3a827927daad6af1ed85aa0f1853b Mon Sep 17 00:00:00 2001
From: Josh Stewart <josh@noisymime.org>
Date: Wed, 25 Jan 2017 11:10:12 +1100
Subject: [PATCH] Considerably better rpmDOT (rpm/s) calculation. Faster and
 more accurate

---
 globals.h     |  2 +-
 speeduino.ino |  6 ++----
 timers.h      |  2 ++
 timers.ino    | 14 +++++++++++++-
 4 files changed, 18 insertions(+), 6 deletions(-)

diff --git a/globals.h b/globals.h
index e2bb6e7..7663f51 100644
--- a/globals.h
+++ b/globals.h
@@ -152,7 +152,7 @@ struct statuses {
   unsigned long TPSlast_time; //The time the previous TPS sample was taken
   byte tpsADC; //0-255 byte representation of the TPS
   byte tpsDOT;
-  int rpmDOT;
+  volatile int rpmDOT;
   byte VE;
   byte O2;
   byte O2_2;
diff --git a/speeduino.ino b/speeduino.ino
index 94501ea..718068d 100644
--- a/speeduino.ino
+++ b/speeduino.ino
@@ -31,7 +31,7 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 #include "math.h"
 #include "corrections.h"
 #include "timers.h"
-//#include "display.h"
+//#include "display.h"  
 #include "decoders.h"
 #include "idle.h"
 #include "auxiliaries.h"
@@ -806,10 +806,8 @@ void loop()
     unsigned long timeToLastTooth = (currentLoopTime - toothLastToothTime);
     if ( (timeToLastTooth < MAX_STALL_TIME) || (toothLastToothTime > currentLoopTime) ) //Check how long ago the last tooth was seen compared to now. If it was more than half a second ago then the engine is probably stopped. toothLastToothTime can be greater than currentLoopTime if a pulse occurs between getting the lastest time and doing the comparison
     {
-      int lastRPM = currentStatus.RPM; //Need to record this for rpmDOT calculation
       currentStatus.RPM = currentStatus.longRPM = getRPM(); //Long RPM is included here
       if(fuelPumpOn == false) { digitalWrite(pinFuelPump, HIGH); fuelPumpOn = true; } //Check if the fuel pump is on and turn it on if it isn't. 
-      currentStatus.rpmDOT = ldiv(1000000, (currentLoopTime - previousLoopTime)).quot * (currentStatus.RPM - lastRPM); //This is the RPM per second that the engine has accelerated/decelleratedin the last loop
     }
     else
     {
@@ -846,7 +844,7 @@ void loop()
     {
       readTPS();
      
-      //Check for launching (clutch) can be done around here too
+      //Check for launching/flat shift (clutch) can be done around here too
       previousClutchTrigger = clutchTrigger;
       if(configPage3.launchHiLo) { clutchTrigger = digitalRead(pinLaunch); }
       else { clutchTrigger = !digitalRead(pinLaunch); } 
diff --git a/timers.h b/timers.h
index 3b660d6..f21727a 100644
--- a/timers.h
+++ b/timers.h
@@ -19,10 +19,12 @@ Hence we will preload the timer with 131 cycles to leave 125 until overflow (1ms
 #ifndef TIMERS_H
 #define TIMERS_H
 
+volatile int loop100ms;
 volatile int loop250ms;
 volatile int loopSec;
 
 volatile unsigned int dwellLimit_uS;
+volatile uint16_t lastRPM_100ms; //Need to record this for rpmDOT calculation
 
 #if defined (CORE_TEENSY)
   IntervalTimer lowResTimer;
diff --git a/timers.ino b/timers.ino
index 9934267..e7be9b5 100644
--- a/timers.ino
+++ b/timers.ino
@@ -40,6 +40,7 @@ void initialiseTimers()
 #endif
 
   dwellLimit_uS = (1000 * configPage2.dwellLimit);
+  lastRPM_100ms = 0;
 }
 
 
@@ -53,10 +54,11 @@ void oneMSInterval() //Most ARM chips can simply call a function
 {
   
   //Increment Loop Counters
+  loop100ms++;
   loop250ms++;
   loopSec++;
 
-unsigned long targetOverdwellTime;
+  unsigned long targetOverdwellTime;
   
   //Overdwell check
   targetOverdwellTime = micros() - dwellLimit_uS; //Set a target time in the past that all coil charging must have begun after. If the coil charge began before this time, it's been running too long
@@ -67,6 +69,16 @@ unsigned long targetOverdwellTime;
   if(ignitionSchedule3.Status == RUNNING) { if(ignitionSchedule3.startTime < targetOverdwellTime && configPage2.useDwellLim) { endCoil3Charge(); } }
   if(ignitionSchedule4.Status == RUNNING) { if(ignitionSchedule4.startTime < targetOverdwellTime && configPage2.useDwellLim) { endCoil4Charge(); } }  
   if(ignitionSchedule5.Status == RUNNING) { if(ignitionSchedule5.startTime < targetOverdwellTime && configPage2.useDwellLim) { endCoil5Charge(); } }
+
+  //Loop executed every 100ms loop
+  //Anything inside this if statement will run every 100ms.
+  if (loop100ms == 100)
+  {
+    loop100ms = 0; //Reset counter
+
+    currentStatus.rpmDOT = (currentStatus.RPM - lastRPM_100ms) * 10; //This is the RPM per second that the engine has accelerated/decelleratedin the last loop
+    lastRPM_100ms = currentStatus.RPM; //Record the current RPM for next calc
+  }
   
   //Loop executed every 250ms loop (1ms x 250 = 250ms)
   //Anything inside this if statement will run every 250ms.