Complete part 2 code

Project_2_Speed_Controller/Part_2_Motor_Response/.gitignore

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+.pio
+.vscode/.browse.c_cpp.db*
+.vscode/c_cpp_properties.json
+.vscode/launch.json
+.vscode/ipch

Project_2_Speed_Controller/Part_2_Motor_Response/include/digital_in.h

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+#ifndef DIGITAL_IN_H
+#define DIGITAL_IN_H
+
+#include <stdint.h>
+
+class Digital_in
+{
+public:
+    Digital_in(int pin);
+
+    void init();
+
+    bool is_hi();
+    bool is_lo();
+
+private:
+    uint8_t pinMask;
+};
+
+#endif

Project_2_Speed_Controller/Part_2_Motor_Response/include/digital_out.h

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+#ifndef DIGITAL_OUT_H
+#define DIGITAL_OUT_H
+
+#include <stdint.h>
+
+class Digital_out
+{
+public:
+    Digital_out(int pin);
+
+    void init();
+    void set_hi();
+    void set_lo();
+    void toggle();
+
+private:
+    uint8_t pinMask;
+};
+
+#endif

Project_2_Speed_Controller/Part_2_Motor_Response/include/encoder.h

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+#ifndef ENCODER_H
+#define ENCODER_H
+
+#include <digital_in.h>
+#include <digital_out.h>
+
+class Encoder
+{
+public:
+    Encoder(int c1Pin, int c2Pin, int ledPin);
+
+    void init();
+    void update();
+    int position();
+    int speed();
+
+private:
+    Digital_in c1;
+    Digital_in c2;
+    Digital_out led;
+
+    bool previousC1;
+    volatile int count;
+    int pastCount;
+    uint32_t pastTime;
+
+};
+
+#endif

Project_2_Speed_Controller/Part_2_Motor_Response/platformio.ini

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+; PlatformIO Project Configuration File
+;
+;   Build options: build flags, source filter
+;   Upload options: custom upload port, speed and extra flags
+;   Library options: dependencies, extra library storages
+;   Advanced options: extra scripting
+;
+; Please visit documentation for the other options and examples
+; https://docs.platformio.org/page/projectconf.html
+
+[env:nanoatmega328new]
+platform = atmelavr
+board = nanoatmega328new
+framework = arduino
+monitor_speed = 115200

Project_2_Speed_Controller/Part_2_Motor_Response/src/digital_in.cpp

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+#include <digital_in.h>
+#include <avr/io.h>
+
+Digital_in::Digital_in(int pin)
+{
+    pinMask = static_cast<uint8_t>(1U << pin);
+}
+
+void Digital_in::init()
+{
+    // Configure pin as input
+    DDRB &= static_cast<uint8_t>(~pinMask);
+
+    // Enable internal pull-up resistor
+    PORTB |= pinMask;
+}
+
+bool Digital_in::is_hi()
+{
+    return (PINB & pinMask) != 0;
+}
+
+bool Digital_in::is_lo()
+{
+    return (PINB & pinMask) == 0;
+}

Project_2_Speed_Controller/Part_2_Motor_Response/src/digital_out.cpp

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+#include <digital_out.h>
+#include <avr/io.h>
+
+Digital_out::Digital_out(int pin)
+{
+    pinMask = static_cast<uint8_t>(1U << pin);
+}
+
+void Digital_out::init()
+{
+    DDRB |= pinMask;
+}
+
+void Digital_out::set_hi()
+{
+    PORTB |= pinMask;
+}
+
+void Digital_out::set_lo()
+{
+    PORTB &= static_cast<uint8_t>(~pinMask);
+}
+
+void Digital_out::toggle()
+{
+    PORTB ^= pinMask;
+}

Project_2_Speed_Controller/Part_2_Motor_Response/src/encoder.cpp

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+#include <encoder.h>
+#include <Arduino.h>
+#include <avr/io.h>
+#include <avr/interrupt.h>
+
+static Encoder* activeEncoder = nullptr;
+
+ISR(PCINT0_vect)
+{
+    if (activeEncoder != nullptr)
+    {
+        activeEncoder->update();
+    }
+}
+
+Encoder::Encoder(int c1Pin, int c2Pin, int ledPin)
+    : c1(c1Pin), c2(c2Pin), led(ledPin),
+      previousC1(false), count(0)
+{
+}
+
+void Encoder::init()
+{
+    c1.init();
+    c2.init();
+    led.init();
+
+    led.set_lo();
+
+    activeEncoder = this;
+
+    // Clear any pending PORTB pin-change interrupt
+    PCIFR |= (1 << PCIF0);
+
+    // Enable pin-change interrupts for PORTB 
+    PCICR |= (1 << PCIE0);
+
+    // Enable interrupt specifically for PB3 / D8 / C1 
+    PCMSK0 |= (1 << PCINT0);
+
+
+    //capture baseline
+    previousC1 = c1.is_hi();
+    count = 0;
+
+    // Enable global interrupts
+    sei();
+
+    // Set initial states for speed
+    pastCount = count;
+    pastTime = micros();
+
+}
+
+void Encoder::update()
+{
+    led.set_lo();
+
+    bool currentC1 = c1.is_hi();
+
+    if (currentC1 != previousC1)
+    {
+        bool currentC2 = c2.is_hi();
+
+        if (currentC1 == currentC2)
+        {
+            count++;
+        }
+        else
+        {
+            count--;
+        }
+
+        previousC1 = currentC1;
+
+        led.set_hi();
+    }
+}
+
+int Encoder::position()
+{
+    uint8_t oldSREG = SREG;
+
+    cli();
+    int currentCount = count;
+    SREG = oldSREG;
+
+    return currentCount;
+}
+
+
+
+int Encoder::speed()
+{
+    int currentCount = position();
+    uint32_t currentTime = micros(); //gives arduino microseconds since program started running
+
+    //from spec sheet we get 1400 counts per revolution from driver 
+    // or from assignment 1: 2100
+    int rpm = ((currentCount-pastCount)*6e7)/((currentTime-pastTime)*2100);  // we turn counts to rotations by dividing by 1400 and microsecond to minutes by multiplying with 60 and 10^6 
+
+    pastTime = currentTime;
+    pastCount = currentCount;
+
+    return rpm;
+}

Project_2_Speed_Controller/Part_2_Motor_Response/src/main.cpp

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+#include <Arduino.h>
+#include <encoder.h>
+#include <digital_out.h>
+
+int main()
+{
+    init();
+
+    Encoder encoder(0, 1, 5);
+
+    Digital_out ain1(3);   // D11
+    Digital_out ain2(4);   // D12
+
+    encoder.init();
+
+    ain1.init();
+    ain2.init();
+
+    // Motor initially OFF
+    ain1.set_lo();
+    ain2.set_lo();
+
+    Serial.begin(115200);
+
+    // Give time to open the serial monitor
+    delay(3000);
+
+    Serial.println("time_ms,rpm");
+
+    // Fresh baseline for speed calculation
+    encoder.speed();
+
+    uint32_t startTime = micros();
+
+    // Step input: motor OFF -> full voltage
+    // This direction should give positive RPM
+    ain1.set_lo();
+    ain2.set_hi();
+
+    while ((micros() - startTime) < 4000000UL)
+    {
+        int rpm = encoder.speed();
+        uint32_t time_ms = (micros() - startTime) / 1000UL;
+
+        Serial.print(time_ms);
+        Serial.print(",");
+        Serial.println(rpm);
+
+        delay(10);
+    }
+
+    // Stop motor
+    ain1.set_lo();
+    ain2.set_lo();
+
+    while (1)
+    {
+    }
+
+    return 0;
+}