Network

Code templates for network communication on MicroPython devices. WiFi and network operations are Cautious tier — inform the user before connecting.

WiFi credentials should never be hardcoded in files saved to the device. Use variables or prompt the user for values.

WiFi Station Mode (Connect to Router)

import network, time, json
try:
    sta = network.WLAN(network.STA_IF)
    sta.active(True)

    ssid = "YOUR_SSID"       # Replace with actual value
    password = "YOUR_PASS"   # Replace with actual value
    sta.connect(ssid, password)

    timeout = 15
    start = time.time()
    while not sta.isconnected():
        if time.time() - start > timeout:
            print("ERROR:WiFi connection timed out after " + str(timeout) + "s")
            raise SystemExit
        time.sleep(0.5)

    ip, mask, gw, dns = sta.ifconfig()
    print("RESULT:" + json.dumps({
        "ip": ip, "mask": mask, "gateway": gw, "dns": dns,
    }))
except Exception as e:
    print("ERROR:" + str(e))

WiFi Access Point Mode

Create a WiFi hotspot on the device:

import network, json
try:
    ap = network.WLAN(network.AP_IF)
    ap.active(True)
    ap.config(essid="ESP32-AP", password="12345678", authmode=network.AUTH_WPA2_PSK)

    ip, mask, gw, dns = ap.ifconfig()
    print("RESULT:" + json.dumps({
        "mode": "AP",
        "ssid": "ESP32-AP",
        "ip": ip,
    }))
except Exception as e:
    print("ERROR:" + str(e))

HTTP Client (urequests)

GET request:

import urequests, json
try:
    r = urequests.get("http://httpbin.org/get")
    print("RESULT:" + json.dumps({
        "status": r.status_code,
        "body_preview": r.text[:200],
    }))
    r.close()
except Exception as e:
    print("ERROR:" + str(e))

POST with JSON:

import urequests, json
try:
    data = {"sensor": "dht22", "temp": 23.5}
    r = urequests.post(
        "http://example.com/api/data",
        json=data,
        headers={"Content-Type": "application/json"}
    )
    print("RESULT:" + json.dumps({"status": r.status_code}))
    r.close()
except Exception as e:
    print("ERROR:" + str(e))

Note:

urequests

is included in most MicroPython firmware builds. For HTTPS, the device needs sufficient memory (ESP32 usually OK, ESP8266 may struggle).

MQTT Publish / Subscribe

Using the built-in

umqtt.simple

module:

from umqtt.simple import MQTTClient
import json, time
try:
    client = MQTTClient(
        "esp32_client",       # Client ID
        "broker.hivemq.com",  # Broker address
        port=1883,
    )
    client.connect()
    print("LOG:Connected to MQTT broker")

    # Publish
    topic = "test/esp32"
    payload = json.dumps({"temp": 23.5, "hum": 61})
    client.publish(topic, payload)

    print("RESULT:" + json.dumps({
        "action": "publish",
        "topic": topic,
        "payload": payload,
    }))

    client.disconnect()
except Exception as e:
    print("ERROR:" + str(e))

Subscribe with callback:

from umqtt.simple import MQTTClient
import json, time
try:
    received = []

    def on_message(topic, msg):
        received.append({"topic": topic.decode(), "msg": msg.decode()})

    client = MQTTClient("esp32_sub", "broker.hivemq.com", port=1883)
    client.set_callback(on_message)
    client.connect()
    client.subscribe(b"test/commands")
    print("LOG:Subscribed, waiting for messages...")

    # Check for messages with timeout
    deadline = time.time() + 10
    while time.time() < deadline:
        client.check_msg()
        time.sleep(0.1)
        if received:
            break

    client.disconnect()
    print("RESULT:" + json.dumps({"received": received}))
except Exception as e:
    print("ERROR:" + str(e))

Note: If

umqtt

is not available, install it:

mpremote mip install umqtt.simple

BLE (Bluetooth Low Energy)

ESP32 BLE advertising example:

import bluetooth, json, struct
try:
    ble = bluetooth.BLE()
    ble.active(True)
    name = "ESP32-BLE"

    # Encode advertising payload
    adv_data = bytearray()
    # Flags
    adv_data += struct.pack("BBB", 2, 0x01, 0x06)
    # Complete name
    name_bytes = name.encode()
    adv_data += struct.pack("BB", len(name_bytes) + 1, 0x09) + name_bytes

    ble.gap_advertise(100000, adv_data)  # Advertise every 100ms

    print("RESULT:" + json.dumps({
        "ble_active": True,
        "name": name,
        "advertising": True,
    }))
except Exception as e:
    print("ERROR:" + str(e))

BLE scan for nearby devices:

import bluetooth, json, time
try:
    ble = bluetooth.BLE()
    ble.active(True)
    devices = []

    def scan_cb(event, data):
        if event == 5:  # _IRQ_SCAN_RESULT
            addr_type, addr, adv_type, rssi, adv_data = data
            addr_hex = ":".join("{:02x}".format(b) for b in addr)
            devices.append({"addr": addr_hex, "rssi": rssi})

    ble.irq(scan_cb)
    ble.gap_scan(5000, 30000, 30000)  # Scan for 5 seconds
    time.sleep(6)

    # Deduplicate by address
    seen = {}
    for d in devices:
        if d["addr"] not in seen or d["rssi"] > seen[d["addr"]]["rssi"]:
            seen[d["addr"]] = d

    print("RESULT:" + json.dumps({"ble_devices": list(seen.values()), "count": len(seen)}))
except Exception as e:
    print("ERROR:" + str(e))

NTP Time Sync

Synchronize device clock from the internet:

import ntptime, time, json
try:
    ntptime.settime()
    t = time.localtime()
    print("RESULT:" + json.dumps({
        "synced": True,
        "utc": "{:04d}-{:02d}-{:02d}T{:02d}:{:02d}:{:02d}Z".format(*t[:6]),
    }))
except Exception as e:
    print("ERROR:NTP sync failed: " + str(e))

Note: Device must be connected to WiFi first. NTP uses UDP port 123.

WebSocket (Minimal Server)

Run a simple WebSocket echo server on the device — useful for real-time data streaming to a browser:

import socket, json, hashlib, binascii
try:
    s = socket.socket()
    s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
    s.bind(("0.0.0.0", 8080))
    s.listen(1)
    print("LOG:WebSocket server on port 8080")
    print("RESULT:" + json.dumps({"server": "started", "port": 8080}))
    # Accept one connection for demo, then close
    # For production, use asyncio-based server
    s.close()
except Exception as e:
    print("ERROR:" + str(e))

For full WebSocket support, consider

micropython-async

or

microdot

framework.