/**
 * FreeRTOS LED Demo
 * 
 * One task flashes an LED at a rate specified by a value set in another task.
 * 
 * Date: December 4, 2020
 * Author: Shawn Hymel
 * License: 0BSD
 *
 * Introduction to RTOS - Solution to Part 3 (Task Scheduling)
 */


// Needed for atoi()
#include <stdlib.h>

// Use only core 1 for demo purposes
#if CONFIG_FREERTOS_UNICORE
  static const BaseType_t app_cpu = 0;
#else
  static const BaseType_t app_cpu = 1;
#endif

// Settings
static const uint8_t buf_len = 20;

// Pins
static const int led_pin = LED_BUILTIN;

// Globals
static int led_delay = 500;   // ms

//*****************************************************************************
// Tasks

// Task: Blink LED at rate set by global variable
void toggleLED(void *parameter) {
  while (1) {
    digitalWrite(led_pin, HIGH);
    vTaskDelay(led_delay / portTICK_PERIOD_MS);
    digitalWrite(led_pin, LOW);
    vTaskDelay(led_delay / portTICK_PERIOD_MS);
  }
}

// Task: Read from serial terminal
// Feel free to use Serial.readString() or Serial.parseInt(). I'm going to show
// it with atoi() in case you're doing this in a non-Arduino environment. You'd
// also need to replace Serial with your own UART code for non-Arduino.
void readSerial(void *parameters) {

  char c;
  char buf[buf_len];
  uint8_t idx = 0;

  // Clear whole buffer
  memset(buf, 0, buf_len);

  // Loop forever
  while (1) {

    // Read characters from serial
    if (Serial.available() > 0) {
      c = Serial.read();

      // Update delay variable and reset buffer if we get a newline character
      if (c == '\n') {
        led_delay = atoi(buf);
        Serial.print("Updated LED delay to: ");
        Serial.println(led_delay);
        memset(buf, 0, buf_len);
        idx = 0;
      } else {
        
        // Only append if index is not over message limit
        if (idx < buf_len - 1) {
          buf[idx] = c;
          idx++  ;
        }
      }
    }
  }
}

//*****************************************************************************
// Main

void setup() {

  // Configure pin
  pinMode(led_pin, OUTPUT);

  // Configure serial and wait a second
  Serial.begin(115200);
  vTaskDelay(1000 / portTICK_PERIOD_MS);
  Serial.println("Multi-task LED Demo");
  Serial.println("Enter a number in milliseconds to change the LED delay.");

  // Start blink task
  xTaskCreatePinnedToCore(  // Use xTaskCreate() in vanilla FreeRTOS
            toggleLED,      // Function to be called
            "Toggle LED",   // Name of task
            1024,           // Stack size (bytes in ESP32, words in FreeRTOS)
            NULL,           // Parameter to pass
            1,              // Task priority
            NULL,           // Task handle
            app_cpu);       // Run on one core for demo purposes (ESP32 only)
            
  // Start serial read task
  xTaskCreatePinnedToCore(  // Use xTaskCreate() in vanilla FreeRTOS
            readSerial,     // Function to be called
            "Read Serial",  // Name of task
            1024,           // Stack size (bytes in ESP32, words in FreeRTOS)
            NULL,           // Parameter to pass
            1,              // Task priority (must be same to prevent lockup)
            NULL,           // Task handle
            app_cpu);       // Run on one core for demo purposes (ESP32 only)

  // Delete "setup and loop" task
  vTaskDelete(NULL);
}

void loop() {
  // Execution should never get here
}