Ultrasonic Sonar Scanner with Raspberry Pi Pico Clone

import machine
import time
import _thread
import math
from machine import UART, Pin, PWM, time_pulse_us

# ==========================================
# 1. CONFIGURATION
# ==========================================

# --- Wi-Fi Settings ---
SSID = "PiedPiper"
PASSWORD = "ErlichBachmanIsAFat"

# --- Servo Calibration ---
# Freq: 50Hz. Standard duty is 1ms to 2ms (approx 1638 to 8192 in u16).
# Depending on your specific servo, you might need to widen these ranges.
SERVO_PIN = 15
SERVO_MIN_US = 1638  # Value for 0 degrees
SERVO_MAX_US = 8192  # Value for 180 degrees
SCAN_DELAY = 0.1    # Time to wait for sensor between steps

# --- Ultrasonic Pins ---
TRIG_PIN = 16
ECHO_PIN = 17

# ==========================================
# 2. SHARED GLOBAL VARIABLES
# ==========================================

servo = PWM(Pin(SERVO_PIN))
servo.freq(50)
trig = Pin(TRIG_PIN, Pin.OUT)
echo = Pin(ECHO_PIN, Pin.IN)

# Thread Lock to prevent reading/writing at same time
data_lock = _thread.allocate_lock()

# The data to be served via JSON
shared_data = {
    "dis": 0,    # Distance in cm
    "rot": 0     # Current Angle (0-180)
}

# ==========================================
# 3. CORE 1: MOTOR & SENSOR CONTROL
# ==========================================

def set_angle(angle):
    duty = SERVO_MIN_US + (SERVO_MAX_US - SERVO_MIN_US) * (angle / 180)
    servo.duty_u16(int(duty))

def get_distance():
    dist_cm = 0
    try:
        trig.low()
        time.sleep_us(2)
        trig.high()
        time.sleep_us(10)
        trig.low()

        # Timeout 30ms (approx 5 meters max) to prevent blocking
        duration = time_pulse_us(echo, 1, 30000) 

        if duration > 0:
            dist_cm = int((duration / 2) / 29.1)
            if dist_cm > 200: dist_cm = 200 # Cap max distance
        else:
            dist_cm = -1 # Out of range
    except OSError:
        dist_cm = -1
    return dist_cm


def core1_task():
    trig.low()
    time.sleep(0.1)

    print("[Core 1] Radar Scan Started")

    current_angle = 0
    accm = 1

    while True:
        set_angle(current_angle)
        time.sleep(SCAN_DELAY)

        dist_cm = get_distance()
        if current_angle >= 180: accm = -1
        if current_angle <= 0: accm = 1

        current_angle += accm

        with data_lock:
            shared_data["dis"] = dist_cm
            shared_data["rot"] = current_angle
            
        print(shared_data)

# ==========================================
# 4. CORE 0: WEB SERVER
# ==========================================

uart = UART(0, baudrate=115200, tx=Pin(0), rx=Pin(1))

def send_at(cmd, wait=1):
    uart.write(cmd + '\r\n')
    time.sleep(wait)
    if uart.any(): return uart.read()
    return b""

def init_wifi():
    print("[Core 0] Init Wi-Fi...")
    send_at("AT+RST", 2)       # Reset module
    send_at("AT+CWMODE=1")
    send_at(f'AT+CWJAP="{SSID}","{PASSWORD}"', 8)
    ip_info = send_at("AT+CIFSR", 2)
    print("[Core 0] IP info:", ip_info)
    send_at("AT+CIPMUX=1")
    send_at("AT+CIPSERVER=1,80")
    print("[Core 0] Server Ready.")

def server_loop():
    buffer = ""

    while True:
        if uart.any():
            try:
                chunk = uart.read().decode('utf-8', 'ignore')
                buffer += chunk

                # Check for Request
                if "+IPD," in buffer:
                    # Parse Connection ID (usually the char after +IPD,)
                    idx = buffer.find("+IPD,")
                    conn_id = buffer[idx + 5]

                    # --- READ SHARED DATA SAFELY ---
                    local_dis = 0
                    local_rot = 0

                    with data_lock:
                        local_dis = shared_data["dis"]
                        local_rot = shared_data["rot"]

                    # --- BUILD RESPONSE ---
                    # We are sending the simplest Valid JSON
                    json_body = '{"dis":' + str(local_dis) + ',"rot":' + str(local_rot) + '}'

                    header = "HTTP/1.1 200 OK\r\n"
                    header += "Content-Type: application/json\r\n"
                    header += "Access-Control-Allow-Origin: *\r\n" # CORS
                    header += "Connection: close\r\n"
                    header += "Content-Length: " + str(len(json_body)) + "\r\n\r\n"

                    full_resp = header + json_body

                    # Send Command
                    uart.write(f"AT+CIPSEND={conn_id},{len(full_resp)}\r\n")
                    time.sleep(0.02) # Short wait for prompt >
                    uart.write(full_resp)

                    # Close Command
                    time.sleep(0.02)
                    uart.write(f"AT+CIPCLOSE={conn_id}\r\n")

                    buffer = "" # Clear buffer for next request

            except Exception as e:
                # If UART garbage causes error, reset buffer
                print("Error:", e)
                buffer = ""

# ==========================================
# 5. EXECUTION START
# ==========================================

print("Reset radar position")
set_angle(0)
time.sleep(0.5)

# Run Core 0 (Wi-Fi) in main thread
init_wifi()
time.sleep(10)
# Start Core 1 (Servo/Sensor) in background
_thread.start_new_thread(core1_task, ())
server_loop()