Prime Injection Pulse impl. (#516)

* Prime Injection Pulse impl.

* Move backup_ram into a separate PR

* fix formatting

firmware/controllers/engine_controller.cpp

@@ -262,6 +262,8 @@ static void periodicSlowCallback(Engine *engine) {
 		writeToFlashIfPending();
 #endif
 		resetAccel();
+	} else {
+		updatePrimeInjectionPulseState(PASS_ENGINE_PARAMETER_SIGNATURE);
 	}
 
 	if (versionForConfigurationListeners.isOld()) {

firmware/controllers/trigger/main_trigger_callback.cpp

@@ -59,6 +59,7 @@
 #include "engine.h"
 #include "efilib2.h"
 #include "aux_valves.h"
+#include "backup_ram.h"
 
 EXTERN_ENGINE
 ;
@@ -66,6 +67,8 @@ extern bool hasFirmwareErrorFlag;
 
 static const char *prevOutputName = NULL;
 
+static InjectionEvent primeInjEvent;
+
 static Logging *logger;
 #if ! EFI_UNIT_TEST
 static pid_s *fuelPidS = &persistentState.persistentConfiguration.engineConfiguration.fuelClosedLoopPid;
@@ -512,6 +515,47 @@ void mainTriggerCallback(trigger_event_e ckpSignalType, uint32_t trgEventIndex D
 	}
 }
 
+// Prime injection pulse, mainly needed for mono-injectors or long intake manifolds.
+static void startPrimeInjectionPulse(DECLARE_ENGINE_PARAMETER_SIGNATURE) {
+#if EFI_PROD_CODE || defined(__DOXYGEN__)
+	// First, we need a protection against 'fake' ignition switch on and off (i.e. no engine started), to avoid repeated prime pulses.
+	// So we check and update the ignition switch counter in non-volatile backup-RAM
+	uint32_t ignSwitchCounter = backupRamLoad(BACKUP_IGNITION_SWITCH_COUNTER);
+	// if we're just toying with the ignition switch, give it another chance eventually...
+	if (ignSwitchCounter > 10)
+		ignSwitchCounter = 0;
+	// start prime injection if this is a 'fresh start'
+	if (ignSwitchCounter == 0) {
+		// fill-in the prime event struct
+#if EFI_UNIT_TEST || defined(__DOXYGEN__)
+		primeInjEvent.engine = engine;
+#endif
+		primeInjEvent.ownIndex = 0;
+		primeInjEvent.isSimultanious = true;
+
+		scheduling_s *sDown = &ENGINE(fuelActuators[0]).signalTimerDown;
+		startSimultaniousInjection(&primeInjEvent);
+		efitimeus_t turnOffTime = getTimeNowUs() + MS2US(CONFIG(startOfCrankingPrimingPulse));
+		scheduleTask(sDown, turnOffTime, (schfunc_t) &endSimultaniousInjection, &primeInjEvent);
+	}
+	// we'll reset it later when the engine starts
+	backupRamSave(BACKUP_IGNITION_SWITCH_COUNTER, ignSwitchCounter + 1);
+#endif /* EFI_PROD_CODE */
+}
+
+void updatePrimeInjectionPulseState(DECLARE_ENGINE_PARAMETER_SIGNATURE) {
+#if EFI_PROD_CODE || defined(__DOXYGEN__)
+	static bool counterWasReset = false;
+	if (counterWasReset)
+		return;
+
+	if (!engine->rpmCalculator.isStopped(PASS_ENGINE_PARAMETER_SIGNATURE)) {
+		backupRamSave(BACKUP_IGNITION_SWITCH_COUNTER, 0);
+		counterWasReset = true;
+	}
+#endif /* EFI_PROD_CODE */
+}
+
 #if EFI_ENGINE_SNIFFER || defined(__DOXYGEN__)
 #include "engine_sniffer.h"
 #endif
@@ -554,6 +598,11 @@ void initMainEventListener(Logging *sharedLogger DECLARE_ENGINE_PARAMETER_SUFFIX
 #endif /* EFI_HISTOGRAMS */
 
 	addTriggerEventListener(mainTriggerCallback, "main loop", engine);
+
+    // We start prime injection pulse at the early init stage - don't wait for the engine to start spinning!
+    if (CONFIG(startOfCrankingPrimingPulse) > 0)
+    	startPrimeInjectionPulse(PASS_ENGINE_PARAMETER_SIGNATURE);
+
 }
 
 #endif /* EFI_ENGINE_CONTROL */

firmware/controllers/trigger/main_trigger_callback.h

@@ -26,4 +26,8 @@ void seTurnPinHigh(InjectionSignalPair *pair);
 void seTurnPinLow(InjectionSignalPair *pair);
 
 float getFuel(int rpm, float key);
+
+// reset injection switch counter if the engine started spinning
+void updatePrimeInjectionPulseState(DECLARE_ENGINE_PARAMETER_SIGNATURE);
+
 #endif /* MAIN_LOOP_H_ */