Add an example using both cores for timing specific work that the blo…

…cking OBD call doesn't effect (#35)

examples/ESP32_dual_core/ESP32_dual_core.ino

@@ -0,0 +1,187 @@
+#include <BluetoothSerial.h>
+#include <ELMduino.h>
+#include <atomic>
+
+const uint8_t led = 2;
+
+ELM327 obd;
+BluetoothSerial SerialBT;
+TaskHandle_t rpm_task;
+TaskHandle_t led_task;
+
+std::atomic<short> rpm{0};
+
+void setup(void)
+{
+    Serial.begin(115200);
+
+    connect_to_obd();
+
+    pinMode(led, OUTPUT);
+
+    // Do blocking OBD call on one core
+    xTaskCreatePinnedToCore(
+        get_rpm_task, // Task function.
+        "Task1",      // Name of task.
+        10000,        // Stack size of task
+        NULL,         // Parameter of the task
+        0,            // Priority of the task
+        &rpm_task,    // Task handle to keep track of created task
+        0);           // Pin task to core 0
+
+    // Do timing specific work on another core
+    xTaskCreatePinnedToCore(
+        flash_led_task, // Task function.
+        "Task2",        // Name of task.
+        10000,          // Stack size of task
+        NULL,           // Parameter of the task
+        0,              // Priority of the task
+        &led_task,      // Task handle to keep track of created task
+        1);             // Pin task to core 1
+
+    delay(500);
+}
+
+void loop()
+{
+    vTaskDelete(NULL);
+}
+
+void flash_led_task(void* parameters)
+{
+    static unsigned long current_time{0};
+    static unsigned long previous_flash_time{0};
+    static const int flash_interval{75};
+    static bool is_on = false;
+
+    for (;;)
+    {
+        current_time = millis();
+
+        if (rpm > 2500)
+        {
+            if (current_time - previous_flash_time >= flash_interval)
+            {
+                if (is_on)
+                {
+                    digitalWrite(led, LOW);
+                }
+                else
+                {
+                    digitalWrite(led, HIGH);
+                }
+
+                previous_flash_time = current_time;
+                is_on = !is_on;
+            }
+        }
+        else
+        {
+            is_on = false;
+            digitalWrite(led, LOW);
+        }
+
+        // Sadly you need this or you will starve the IDLE task
+        delay(1);
+    }
+}
+
+void get_rpm_task(void* parameters)
+{
+    for (;;)
+    {
+        read_rpm();
+        // Sadly you need this or you will starve the IDLE task
+        delay(1);
+    }
+}
+
+void connect_to_obd()
+{
+    SerialBT.begin("led_flasher", true);
+
+    bool connected = SerialBT.connect("OBDII");
+
+    if(connected)
+    {
+        Serial.println("Connected Succesfully!");
+    }
+    else
+    {
+        while(!SerialBT.connected(10000))
+        {
+            Serial.println("Failed to connect. Make sure remote device is available and in range, then restart app.");
+        }
+    }
+
+    while(!obd.begin(SerialBT))
+    {
+        Serial.println("Couldn't connect to OBD scanner");
+    }
+
+    Serial.println("Connected to ELM327");
+}
+
+void read_rpm()
+{
+    static unsigned long current_time{0};
+    static unsigned long previous_rpm_time{0};
+    static const int rpm_interval{112};
+
+    current_time = millis();
+
+    if (current_time - previous_rpm_time >= rpm_interval)
+    {
+        rpm = static_cast<short>(obd.rpm());
+        Serial.print("RPM: "); Serial.println(rpm);
+        previous_rpm_time = current_time;
+
+        if (obd.status != ELM_SUCCESS)
+        {
+            print_error();
+        }
+    }
+}
+
+void print_error()
+{
+    Serial.print("Received: ");
+    for (byte i = 0; i < obd.recBytes; i++)
+    {
+        Serial.write(obd.payload[i]);
+    }
+    Serial.println();
+
+    if (obd.status == ELM_SUCCESS)
+    {
+        Serial.println(F("\tELM_SUCCESS"));
+    }
+    else if (obd.status == ELM_NO_RESPONSE)
+    {
+        Serial.println(F("\tERROR: ELM_NO_RESPONSE"));
+    }
+    else if (obd.status == ELM_BUFFER_OVERFLOW)
+    {
+        Serial.println(F("\tERROR: ELM_BUFFER_OVERFLOW"));
+    }
+    else if (obd.status == ELM_UNABLE_TO_CONNECT)
+    {
+        Serial.println(F("\tERROR: ELM_UNABLE_TO_CONNECT"));
+    }
+    else if (obd.status == ELM_NO_DATA)
+    {
+        Serial.println(F("\tERROR: ELM_NO_DATA"));
+    }
+    else if (obd.status == ELM_STOPPED)
+    {
+        Serial.println(F("\tERROR: ELM_STOPPED"));
+    }
+    else if (obd.status == ELM_TIMEOUT)
+    {
+        Serial.println(F("\tERROR: ELM_TIMEOUT"));
+    }
+    else if (obd.status == ELM_TIMEOUT)
+    {
+        Serial.println(F("\tERROR: ELM_GENERAL_ERROR"));
+    }
+}