knock sensing peak detect (#2910)

* knock peak detect

* comments

* comment

* initialize

* test

* fix warnings while we're here

* those are functions, not values

* ram

firmware/controllers/actuators/boost_control.h

@@ -11,7 +11,7 @@
 #include "closed_loop_controller.h"
 #include "pid.h"
 
-class IPwm;
+struct IPwm;
 
 class BoostController : public ClosedLoopController<float, percent_t> {
 public:

firmware/controllers/actuators/gppwm/gppwm_channel.h

@@ -6,7 +6,7 @@
 
 struct gppwm_channel;
 class OutputPin;
-class IPwm;
+struct IPwm;
 class ValueProvider3D;
 
 class GppwmChannel {

firmware/controllers/engine_controller.cpp

@@ -698,7 +698,7 @@ void initEngineContoller(DECLARE_ENGINE_PARAMETER_SUFFIX) {
  * UNUSED_SIZE constants.
  */
 #ifndef RAM_UNUSED_SIZE
-#define RAM_UNUSED_SIZE 1500
+#define RAM_UNUSED_SIZE 1400
 #endif
 #ifndef CCM_UNUSED_SIZE
 #define CCM_UNUSED_SIZE 300

firmware/controllers/sensors/software_knock.cpp

@@ -1,4 +1,3 @@
-
 #include "global.h"
 #include "engine.h"
 #include "biquad.h"
@@ -7,6 +6,7 @@
 #include "knock_logic.h"
 #include "software_knock.h"
 #include "thread_priority.h"
+#include "peak_detect.h"
 
 #if EFI_SOFTWARE_KNOCK
 
@@ -15,9 +15,10 @@ EXTERN_ENGINE;
 #include "knock_config.h"
 #include "ch.hpp"
 
-NO_CACHE adcsample_t sampleBuffer[2000];
-int8_t currentCylinderIndex = 0;
-Biquad knockFilter;
+static NO_CACHE adcsample_t sampleBuffer[2000];
+static int8_t currentCylinderIndex = 0;
+static efitick_t lastKnockSampleTime = 0;
+static Biquad knockFilter;
 
 static volatile bool knockIsSampling = false;
 static volatile bool knockNeedsProcess = false;
@@ -141,6 +142,7 @@ void startKnockSampling(uint8_t cylinderIndex) {
 	currentCylinderIndex = cylinderIndex;
 
 	adcStartConversionI(&KNOCK_ADC, conversionGroup, sampleBuffer, sampleCount);
+	lastKnockSampleTime = getTimeNowNt();
 }
 
 class KnockThread : public ThreadController<256> {
@@ -164,6 +166,10 @@ void initSoftwareKnock() {
 	}
 }
 
+using PD = PeakDetect<float, MS2NT(100)>;
+static PD peakDetectors[12];
+static PD allCylinderPeakDetector;
+
 void processLastKnockEvent() {
 	if (!knockNeedsProcess) {
 		return;
@@ -190,16 +196,27 @@ void processLastKnockEvent() {
 		sumSq += filtered * filtered;
 	}
 
+	// take a local copy
+	auto lastKnockTime = lastKnockSampleTime;
+
+	// We're done with inspecting the buffer, another sample can be taken
+	knockNeedsProcess = false;
+
 	// mean of squares (not yet root)
 	float meanSquares = sumSq / localCount;
 
 	// RMS
 	float db = 10 * log10(meanSquares);
 
-	tsOutputChannels.knockLevels[currentCylinderIndex] = roundf(clampF(-100, db, 100));
-	tsOutputChannels.knockLevel = db;
+	// clamp to reasonable range
+	db = clampF(-100, db, 100);
+
+	// Pass through peak detector
+	float cylPeak = peakDetectors[currentCylinderIndex].detect(db, lastKnockTime);
+
+	tsOutputChannels.knockLevels[currentCylinderIndex] = roundf(cylPeak);
+	tsOutputChannels.knockLevel = allCylinderPeakDetector.detect(db, lastKnockTime);
 
-	knockNeedsProcess = false;
 }
 
 void KnockThread::ThreadTask() {

firmware/util/peak_detect.h

@@ -0,0 +1,25 @@
+#pragma once
+
+#include "rusefi_types.h"
+
+/**
+ * Stores the recent peak value, preventing loss of intermittent peaks in a signal.
+ */
+template <typename TValue, efitick_t TTimeoutPeriod>
+class PeakDetect {
+public:
+	TValue detect(TValue currentValue, efitick_t nowNt) {
+		if ((nowNt > m_lastPeakTime + TTimeoutPeriod) ||	// if timed out
+			(currentValue > m_peak)) {						// or current is higher than the previous peak
+			// store new peak and time
+			m_peak = currentValue;
+			m_lastPeakTime = nowNt;
+		}
+
+		return m_peak;
+	}
+
+private:
+	TValue m_peak = std::numeric_limits<TValue>::min();
+	efitick_t m_lastPeakTime = std::numeric_limits<efitick_t>::min();
+};

unit_tests/tests/test_util.cpp

@@ -24,6 +24,7 @@
 #include "io_pins.h"
 #include "efi_gpio.h"
 #include "efilib.h"
+#include "peak_detect.h"
 
 #include "gtest/gtest.h"
 
@@ -490,3 +491,24 @@ TEST(util, datalogging) {
 //	printf("Got [%s]\r\n", LOGGING_BUFFER);
 //	ASSERT_STREQ("rusEfiVersion,776655@321ID DEFAULT_FRANKENSO 239,", LOGGING_BUFFER);
 }
+
+TEST(util, PeakDetect) {
+	constexpr int startTime = 50;
+	constexpr int timeout = 100;
+	PeakDetect<int, timeout> dut;
+
+	// Set a peak
+	EXPECT_EQ(dut.detect(1000, startTime), 1000);
+
+	// Smaller value at the same time is ignored
+	EXPECT_EQ(dut.detect(500, startTime), 1000);
+
+	// Larger value at the same time raises the peak
+	EXPECT_EQ(dut.detect(1500, startTime), 1500);
+
+	// Small value at almost the timeout is ignored
+	EXPECT_EQ(dut.detect(500, startTime + timeout - 1), 1500);
+
+	// Small value past the timeout is used
+	EXPECT_EQ(dut.detect(500, startTime + timeout + 1), 500);
+}