// Standard Arduino Code to Read Analog Value from A0, Compare with 500, and Control LED

const int ledPin = 13; // Pin where the LED is connected

void setup() {
  // Start the serial communication
  Serial.begin(9600);

  // Initialize the LED pin as an output
  pinMode(ledPin, OUTPUT);
}

void loop() {
  // Read the analog value from pin A0
  int analogValue = analogRead(A0);

  // Split the analog value into lower and higher bytes
  uint8_t lowerByte = analogValue & 0xFF; // Lower 8 bits of the analog value
  uint8_t higherByte = (analogValue >> 8) & 0x03; // Higher 2 bits of the analog value (since analogRead returns a 10-bit value)

  // Inline assembly to load the lowerByte and higherByte into r24 and r25 respectively
  asm volatile (
    "mov r24, %0 \n\t"
    "mov r25, %1 \n\t"
    :
    : "r" (lowerByte), "r" (higherByte) // Input operands
    : "r24", "r25" // Clobbered registers
  );

  // Variable to store the result of the comparison
  uint8_t result;

 // Inline assembly to compare combinedValue with 819 (0x0333) and set result
asm volatile (
  "cpi r25, 3 \n\t" // Compare the higher byte of combinedValue (r25) with 3 (higher byte of 819)
  "brlo less_than_819 \n\t"
  "brne greater_or_equal_819 \n\t" // Branch if r25 is not equal to 3
  "cpi r24, 51 \n\t" // If r25 equals 3, compare the lower byte of combinedValue (r24) with 51 (lower byte of 819)
  "brlo less_than_819 \n\t" // Branch if r24 is less than 51
  "greater_or_equal_819: \n\t"
  "ldi r18, 1 \n\t" // Load 1 into r18 if combinedValue >= 819
  "rjmp end_compare \n\t" // Jump to end_compare
"less_than_819: \n\t"
  "ldi r18, 0 \n\t" // Load 0 into r18 if combinedValue < 819
"end_compare: \n\t"
  "mov %0, r18 \n\t" // Move the result from r18 to result
  : "=r" (result) // Output operand
  : // No input operands
  : "r18", "r24", "r25" // Clobbered registers
);

  // Control the LED based on the comparison result
  if (result) {
    // Turn the LED on if the value is above or equal to 500
    digitalWrite(ledPin, HIGH);
  } else {
    // Turn the LED off if the value is less than 500
    digitalWrite(ledPin, LOW);
  }

  // Print the analog value to the serial monitor
  Serial.println(analogValue);

  // Add a small delay to stabilize the readings
  delay(100);
}