Added mapping tables for the intake/exhaust valves

ArduinoFreevalve/ArduinoFreevalve.ino

@@ -0,0 +1,92 @@
+// An Arduino program for controlling valve timing on a 6.5HP Predator engine from Harbor Freight.
+//
+// License goes here?
+//
+// Wesley Kagan, 2020
+// Ric Allinson, 2020
+
+// Pins assignment.
+const int HALL_MAGNET = 2;
+const int EXHAUST_V = 12;
+const int INTAKE_V = 13;
+
+// Control constants.
+const int DEG_PER_MAGNET = 6; // Number of degrees for per magnet.
+const int ROTATION_TWO = (720/DEG_PER_MAGNET)-1;   // Number of interrupts in the full cycle.
+const int ROTATION_ONE = (720/DEG_PER_MAGNET)-2; // Number of interrupts in a half cycle.
+
+// Runtime mapping variables.
+bool intakeMap[ROTATION_TWO] = {};  // Intake open/close mapping is equal the total number of interrupts for two rotations.
+bool exhaustMap[ROTATION_TWO] = {}; // Exhaust open/close mapping is equal the total number of interrupts for two rotations.
+
+// ISR variables.
+volatile int hallCounter = 0;           // The number of magnets after the last TDC.
+volatile bool secondRotation = false;   // "true" if the cam is on its second rotation.
+volatile bool printLog = false;         // Used to stop duplicate values from printing in the loop.
+volatile unsigned long timeGap = 0;     // Function level time between interrupts.
+volatile unsigned long lastTimeGap = 0; // Global level time between interrupts.
+
+void setup() {
+  Serial.begin(115200);
+  pinMode(HALL_MAGNET, INPUT);
+  attachInterrupt(0, magnetDetect, RISING);
+  pinMode(INTAKE_V, OUTPUT);
+  pinMode(EXHAUST_V, OUTPUT);
+  // Load mappings here.
+  // intakeMap = ?
+  // exhaustMap = ?
+}
+
+void loop() {
+  // This may not print all values. Only the most recent from the last interrupt.
+  if(printLog){
+    Serial.print(lastTimeGap);
+    Serial.print(hallCounter);
+    Serial.println(secondRotation);
+    printLog = false;
+  }
+}
+
+// This function will be called about every ~263.16usec at the maximum RPM of 3800.
+// The missing tooth will come by roughly every 15.79 ms.
+// (1 rev / 60 pulses) * (1 min / 3800 rev) * (60 sec / min) = 1 / 3800 sec/pulse = ~263.16usec.
+void magnetDetect() {
+  // Increment the counter to keep track of the position.
+  hallCounter++;
+
+  // Get the time gap between this interrupt and the last.
+  // Returns the number of microseconds since the Arduino board began running the current program.
+  // This number will overflow (go back to zero), after approximately 70 minutes.
+  // On 16 MHz Arduino boards (e.g. Duemilanove and Nano),
+  // this function has a resolution of four microseconds (i.e. the value returned is always a multiple of four).
+  // On 8 MHz Arduino boards (e.g. the LilyPad), this function has a resolution of eight microseconds.
+  timeGap = micros() - lastTimeGap;
+
+  // Find the missing tooth for Top Dead Center (TDC).
+  if (timeGap >= lastTimeGap * 3 / 2) {
+    // On the second rotation reset the hallCounter.
+    if (secondRotation) {
+      hallCounter = 0;
+    } else {
+      hallCounter = ROTATION_ONE; // Forcing the counter in case of drift over a rotation.
+    }
+    // Flip the secondRotation.
+    secondRotation = !secondRotation;
+  }
+
+  // Store the last time difference so we can use it in the next interrupt.
+  lastTimeGap = timeGap;
+
+  // If the hallCounter is greater than the mapping index reset it.
+  // This would only happen when the missing tooth was NOT detected.
+  if (hallCounter >= ROTATION_TWO) {
+    hallCounter = 0;
+  }
+
+  // Use the intake/exhaust maps to open or close the valves.
+  digitalWrite(INTAKE_V, intakeMap[hallCounter]);
+  digitalWrite(EXHAUST_V, exhaustMap[hallCounter]);
+
+  // Tells the loop() that values have changed.
+  printLog = true;
+}

README.md

@@ -1,9 +1,16 @@
-# Freevalve_Arduino
-Codebase for the Arduino Freevalve Project- found here: www.youtube.com/c/wesleykagan 
+# Arduino Freevalve
+
+Repository for the Arduino Freevalve Project at www.youtube.com/c/wesleykagan 
+
+## Overview
+
+This code is tested with the [Harbor Freight 6.5hp 212cc OHC Horizontal Shaft Gas Engine EPA&CARB](https://www.harborfreight.com/engines-generators/gasoline-engines/65-hp-212cc-ohv-horizontal-shaft-gas-engine-epacarb-69727.html)
+
+## Original README
 
 Okay, so this is a super early stage of this project, but as of this post, it does work in the configuration uploaded.
 
-If you want to do nothing else becides make the test engine run, edit the two degree functions as noted in the comments. One is intake, one is exhaust. It will require some
+If you want to do nothing else besides make the test engine run, edit the two degree functions as noted in the comments. One is intake, one is exhaust. It will require some
 tweaking to perfectly work. My values were around 252 degrees Open and 102 Close (next cycle) For exhaust, and then 30 degrees open and 252 Closed for intake. I will update as I get a better understanding of the abilities- there's a few odd things with this cam that I'm still working through.
 
 CAD files can be found here: https://www.thingiverse.com/thing:4678730