After getting my robot car to navigate autonomously around the next challenge was to have it hone in on a beacon. The initial suggestion was to use another Acebott ESP32 broadcasting a repeated Bluetooth signal.

In short, this ended up failing simply because the Bluetooth signal was simply not strong enough across any meaningful distance (that is, greater than 2 metres).

It want to make this project work and the suggested next options is to use something called ESP-NOW.

ESP-NOW: Direct Device-to-Device Communication for ESP32 Projects

What is ESP-NOW?

ESP-NOW is a proprietary wireless communication protocol developed by Espressif that allows ESP32 and ESP8266 devices to communicate directly with each other without requiring a Wi-Fi router, access point, or internet connection.

Think of it as a lightweight, low-latency messaging system that uses the ESP32’s Wi-Fi radio to exchange data directly between devices.

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Key Benefits

• No Wi-Fi network required
• Low latency communication
• Low power consumption
• Simple device-to-device messaging
• Works alongside Wi-Fi in many scenarios
• Native support on ESP32 hardware
• Typical range often exceeds BLE

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How It Works

Rather than sending data through a router:

ESP32 —> Router —> ESP32

ESP-NOW allows direct communication:

ESP32 <—–> ESP32

Each device is identified by its MAC address, allowing messages to be exchanged directly.

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Typical Uses

ESP-NOW is popular for:

• Robot-to-robot communication
  

• Sensor networks
  

• Remote controls
  

• Home automation
  

• Wireless telemetry
  

• Drone communications
  

• IoT projects requiring low latency

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For ESP32-to-ESP32 projects, ESP-NOW is often preferred over BLE when communication range and update frequency are important.

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Using ESP-NOW for Robot Navigation

A robot can receive regular beacon packets from a stationary ESP32 and use that information to estimate whether it is moving closer to or further away from the destination.

Example:

-85 dBm = Far

-70 dBm = Closer

-55 dBm = Very Close

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Limitations

ESP-NOW provides:

✅ Fast communication

✅ Good range

✅ Direct device-to-device connectivity

ESP-NOW does not provide:

❌ Precise distance measurements

❌ Direction information

❌ Indoor positioning

For navigation applications, RSSI values can be affected by:

• Walls
  

• Furniture
  

• Metal objects
  

• Reflections
  

• People moving through the environment

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Why ESP-NOW Matters

For ESP32-based projects, ESP-NOW offers a simple and effective way to exchange data between devices without the complexity of Wi-Fi networking. It is particularly useful when low latency, low power consumption, and direct communication are more important than internet connectivity.

For robotics, ESP-NOW can provide a low-cost method for building wireless beacons, sharing telemetry, and coordinating multiple robots using hardware many makers already have available.

Apparently, I can use ESP-NOW and still have the Robot car connected to the Internet via Wifi. Given that it won;t cost me anything except some time to code, let’s see how we go.