revolutionTime should be owned by crank math module.

speeduino/comms_CAN.cpp

@@ -305,7 +305,7 @@ void DashMessage(uint16_t DashMessageID)
     case CAN_HALTECH_DATA3:
       temp_Advance = currentStatus.advance * 10U; //Note: Signed value
       //Convert PW into duty cycle
-      temp_DutyCycle = (fuelSchedule1.pw * 100UL * currentStatus.nSquirts) / revolutionTime; 
+      temp_DutyCycle = (fuelSchedule1.pw * 100UL * currentStatus.nSquirts) / getRevolutionTime(); 
       if (configPage2.strokes == FOUR_STROKE) { temp_DutyCycle = temp_DutyCycle / 2U; }
 
       outMsg.len = 8;

speeduino/corrections.cpp

@@ -30,6 +30,7 @@ There are 2 top level functions that call more detailed corrections for Fuel and
 #include "maths.h"
 #include "sensors.h"
 #include "src/PID_v1/PID_v1.h"
+#include "crankMaths.h"
 
 long PID_O2, PID_output, PID_AFRTarget;
 /** Instance of the PID object in case that algorithm is used (Always instantiated).
@@ -1096,11 +1097,11 @@ uint16_t correctionsDwell(uint16_t dwell)
     pulsesPerRevolution = (configPage2.nCylinders >> 1);
     dwellPerRevolution = dwellPerRevolution * pulsesPerRevolution;
   }
-  if(dwellPerRevolution > revolutionTime)
+  if(dwellPerRevolution > getRevolutionTime())
   {
     //Possibly need some method of reducing spark duration here as well, but this is a start
-    uint16_t adjustedSparkDur = udiv_32_16(sparkDur_uS * revolutionTime, dwellPerRevolution);
-    tempDwell = udiv_32_16(revolutionTime, (uint16_t)pulsesPerRevolution) - adjustedSparkDur;
+    uint16_t adjustedSparkDur = udiv_32_16(sparkDur_uS * getRevolutionTime(), dwellPerRevolution);
+    tempDwell = udiv_32_16(getRevolutionTime(), (uint16_t)pulsesPerRevolution) - adjustedSparkDur;
   }
 
   return tempDwell;

speeduino/crankMaths.cpp

@@ -1,4 +1,3 @@
-#include "globals.h"
 #include "crankMaths.h"
 #include "bit_shifts.h"
 
@@ -13,23 +12,40 @@ int rpmDelta;
 typedef uint32_t UQ24X8_t;
 static constexpr uint8_t UQ24X8_Shift = 8U;
 
-/** @brief uS per degree at current RPM in UQ24.8 fixed point */
+/** @brief µS per degree at current RPM in UQ24.8 fixed point 
+ * 
+ * Ranges between 
+ *   * 1040649 (4065.039 µS/°) at MIN_RPM/MIN_REVOLUTION_TIME
+ *   * 2370    (9.258333 µS/°) at MAX_RPM/MAX_REVOLUTION_TIME
+*/
 static  UQ24X8_t microsPerDegree;
 static constexpr uint8_t microsPerDegree_Shift = UQ24X8_Shift;
 
 typedef uint16_t UQ1X15_t;
 static constexpr uint8_t UQ1X15_Shift = 15U;
 
-/** @brief Degrees per uS in UQ1.15 fixed point.
+/** @brief Degrees per µS in UQ1.15 fixed point.
  * 
- * Ranges from 8 (0.000246) at MIN_RPM to 3542 (0.108) at MAX_RPM
+ * Ranges between 
+ *   * 8    (0.000246 °/µS) at MIN_RPM/MIN_REVOLUTION_TIME
+ *   * 3539 (0.108011 °/µS) at MAX_RPM/MAX_REVOLUTION_TIME
  */
 static UQ1X15_t degreesPerMicro;
 static constexpr uint8_t degreesPerMicro_Shift = UQ1X15_Shift;
 
-void setAngleConverterRevolutionTime(uint32_t revolutionTime) {
-  microsPerDegree = div360(lshift<microsPerDegree_Shift>(revolutionTime));
-  degreesPerMicro = (uint16_t)UDIV_ROUND_CLOSEST(lshift<degreesPerMicro_Shift>(UINT32_C(360)), revolutionTime, uint32_t);
+/** @brief The time in µS that one revolution would take at current speed */
+uint32_t revolutionTime = MIN_REVOLUTION_TIME; // cppcheck-suppress misra-c2012-8.4 ; To allow inlining in header
+
+bool setRevolutionTime(uint32_t revTime) {
+  bool hasChanged = (revTime!=revolutionTime) && (revTime>=MIN_REVOLUTION_TIME) && (revTime<MAX_REVOLUTION_TIME);
+
+  if (hasChanged) {
+    revolutionTime = revTime;
+    microsPerDegree = div360(lshift<microsPerDegree_Shift>(revTime));
+    degreesPerMicro = (uint16_t)UDIV_ROUND_CLOSEST(lshift<degreesPerMicro_Shift>(UINT32_C(360)), revTime, uint32_t);
+  }
+
+  return hasChanged;
 }
 
 uint32_t angleToTimeMicroSecPerDegree(uint16_t angle) {
@@ -38,8 +54,8 @@ uint32_t angleToTimeMicroSecPerDegree(uint16_t angle) {
 }
 
 uint16_t timeToAngleDegPerMicroSec(uint32_t time) {
-    uint32_t degFixed = time * (uint32_t)degreesPerMicro;
-    return rshift_round<degreesPerMicro_Shift>(degFixed);
+  uint32_t degFixed = time * (uint32_t)degreesPerMicro;
+  return rshift_round<degreesPerMicro_Shift>(degFixed);
 }
 
 #if SECOND_DERIV_ENABLED!=0
@@ -83,4 +99,4 @@ void doCrankSpeedCalcs(void)
           timePerDegreex16 = ldiv( 2666656L, currentStatus.RPM + rpmDelta).quot; //This gives accuracy down to 0.1 of a degree and can provide noticeably better timing results on low resolution triggers
       }
 }
-#endif
+#endif

speeduino/crankMaths.h

@@ -1,8 +1,45 @@
 #ifndef CRANKMATHS_H
 #define CRANKMATHS_H
 
+/**
+ * @file
+ * 
+ * @brief Crank revolution based mathemtical functions. 
+ * 
+ */
+
 #include "maths.h"
-#include "globals.h"
+
+/** @brief At 1 RPM, each degree of angular rotation takes this many microseconds */
+static constexpr uint32_t MICROS_PER_DEG_1_RPM = UDIV_ROUND_CLOSEST(MICROS_PER_MIN, 360UL, uint32_t);
+
+/** @brief The maximum rpm that the ECU will attempt to run at. 
+ * 
+ * It is NOT related to the rev limiter, but is instead dictates how fast certain operations will be
+ * allowed to run. Lower number gives better performance 
+ **/
+static constexpr uint16_t MAX_RPM = 18000U;
+
+/** @brief Absolute minimum RPM that the crank math (& therefore all of Speeduino) can be used with.
+ * 
+ * This is dictated by the use of uint16_t as the base type for storing
+ * time --> angle conversion factor (degreesPerMicro)
+*/
+static constexpr uint16_t MIN_RPM = (uint16_t)UDIV_ROUND_UP(MICROS_PER_DEG_1_RPM, (uint32_t)UINT16_MAX/16UL, uint32_t);
+
+/**
+ * @brief Minumum time in µS that one crank revolution can take.
+ * 
+ * @note: many calculations are done over 2 revolutions (cycles), in which case this would be doubled 
+ */
+static constexpr uint16_t MIN_REVOLUTION_TIME = MICROS_PER_MIN/MAX_RPM;
+
+/**
+ * @brief Maximum time in µS that one crank revolution can take.
+ * 
+ * @note: many calculations are done over 2 revolutions (cycles), in which case this would be doubled 
+ */
+static constexpr uint32_t MAX_REVOLUTION_TIME = MICROS_PER_MIN/MIN_RPM;
 
 /**
  * @brief Makes one pass at nudging the angle to within [0,CRANK_ANGLE_MAX_IGN]
@@ -28,51 +65,58 @@ static inline int16_t injectorLimits(int16_t angle)
     return tempAngle;
 }
 
-/** @brief At 1 RPM, each degree of angular rotation takes this many microseconds */
-#define MICROS_PER_DEG_1_RPM INT32_C(166667)
-
-/** @brief The maximum rpm that the ECU will attempt to run at. 
+/**
+ * @brief Set the revolution time, from which the degree<-->angle conversions are derived
  * 
- * It is NOT related to the rev limiter, but is instead dictates how fast certain operations will be
- * allowed to run. Lower number gives better performance 
- **/
-#define MAX_RPM INT16_C(18000)
-
-/** @brief Absolute minimum RPM that the crank math (& therefore all of Speeduino) can be used with 
+ * If the return value is true, then the calculated RPM (@ref rpmFromRevolutionTime) and 
+ * degree<-->angle conversions (@ref angleToTimeMicroSecPerDegree, @ref timeToAngleDegPerMicroSec) will change.
  * 
- * This is dictated by the use of uint16_t as the base type for storing
- * angle<->time conversion factor (degreesPerMicro)
-*/
-#define MIN_RPM ((MICROS_PER_DEG_1_RPM/(UINT16_MAX/16UL))+1UL)
+ * @param revTime The crank revolution time in µS.
+ * @return true If the revolution time has changed
+ * @return false If the new time is the same as the current revolution time.
+ */
+bool setRevolutionTime(uint32_t revTime);
 
 /**
- * @brief Set the revolution time, from which some of the degree<-->angle conversions are derived
+ * @brief Get the latest revolution time
  * 
- * @param revolutionTime The crank revolution time.
+ * @return uint32_t The revolution time, limited to [MIN_REVOLUTION_TIME, MAX_REVOLUTION_TIME)
  */
-void setAngleConverterRevolutionTime(uint32_t revolutionTime);
+static inline uint32_t getRevolutionTime(void) {
+  extern uint32_t revolutionTime;
+  return revolutionTime;
+}
 
 /**
- * @name Converts angular degrees to the time interval that amount of rotation
- * will take at current RPM.
+ * @brief Converts angular degrees to the time interval that amount of rotation
+ * will take at the current crank revolution time (@ref setRevolutionTime).
  * 
  * Based on angle of [0,720] and min/max RPM, result ranges from
- * 9 (MAX_RPM, 1 deg) to 2926828 (MIN_RPM, 720 deg)
+ * 9 (MAX_RPM, 1 deg) to 2926828 (MIN_RPM, 720 deg). I.e. 24 bits
  *
  * @param angle Angle in degrees
- * @return Time interval in uS
+ * @return Time interval in µS
  */
 uint32_t angleToTimeMicroSecPerDegree(uint16_t angle);
 
 /**
- * @name Converts a time interval in microsecods to the equivalent degrees of angular (crank)
- * rotation at current RPM.
+ * @brief Converts a time interval in µS to the equivalent degrees of angular (crank)
+ * rotation at the current crank revolution time (@ref setRevolutionTime).
  *
  * Inverse of angleToTimeMicroSecPerDegree
  *
- * @param time Time interval in uS
+ * @param time Time interval in µS
  * @return Angle in degrees
  */
 uint16_t timeToAngleDegPerMicroSec(uint32_t time);
 
+/** @brief Calculate RPM based on the current crank revolution time (@ref setRevolutionTime). */
+static inline uint16_t rpmFromRevolutionTime(void) {
+  if (getRevolutionTime()<=(uint32_t)UINT16_MAX) {
+    return udiv_32_16_closest(MICROS_PER_MIN, getRevolutionTime());
+  } else {
+    return UDIV_ROUND_CLOSEST(MICROS_PER_MIN, getRevolutionTime(), uint32_t);
+  }
+}
+
 #endif