I think it might be possible to construct a ESP32-NOW Gateway...
[ESP-NOW Nodes] ---> [ESP32-S2 Gateway] ---> [MQTT Broker] ---> Node-RED
Possible experiment for the weekend.
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Dave, this has been around for some time -
esp-now is nice, except for one downside (to me) - a message is limited to 250 bytes, which should be sufficient for many applications but it takes away some flexibility.
I couldn't wait until the weekend - had to have a play today.
I've managed to create, using Micro-Python, a script for a 'now_sender' and a 'now_gateway'.
Note: You will need to change the suffix from .txt to .py as the Forum doesn't allow Python files.
now_gateway.txt (2.0 KB)
now_sender_v1.txt (1.4 KB)
The scripts will auto-discover the MAC addresses needed for communication.
You need to make sure the sender is on the same WiFi channel as the Gateway to MQTT.
Having got a simple 'Sender' to 'Gateway' setup working I intend to explore what I can do with ESP-NOW further. For example, sending commands (from the Gateway) to the Sender to get it send BME280 T/H/P readings on-demand or change its parameters (like update intervals).
ESP-NOW is a proprietary, low-power, peer-to-peer communication protocol developed by Espressif. It doesn’t rely on a WiFi router.
Features:
- Peer-to-peer communication: Devices can communicate directly without a router or internet.
- Low-latency: Message delivery is very fast (milliseconds).
- Broadcast support: Can send to a single peer or broadcast to multiple devices.
- Lightweight protocol: Minimal overhead, just sending raw data or JSON.
- MAC address based: Each device identifies peers by MAC addresses.
- No IP stack needed: Works at the link layer.
Benefits:
- Low power consumption: Devices can stay in sleep mode most of the time.
- Reliable for small data: Perfect for sensor networks or simple control messages.
- No WiFi network needed: Useful in remote areas or ad-hoc networks.
- Fast discovery and communication: Can instantly send small packets.
Limitations:
- Short range: Similar to WiFi (depends on antenna and environment).
- Limited payload: Max ~250 bytes per packet.
- Limited network complexity: Best for small networks (20-30 nodes practical).
- No encryption by default: Requires extra configuration for security.
Comparison Table
| Feature | ESP-NOW | WiFi (Conventional) |
|---|---|---|
| Network Type | Peer-to-peer | Router-based |
| Latency | Very low (ms) | Moderate (ms → s) |
| Payload | Small (~250 bytes) | Large (KB → MB) |
| Power | Very low | Higher |
| Range | ~100 m line-of-sight | ~100 m (depends on AP) |
| Scalability | Limited (20–30 nodes) | High (hundreds of nodes) |
| Security | Optional | Standard (WPA2/WPA3, TLS) |
| Internet Access |  |
 |
| Best Use Case | Sensor networks, remote controls, IoT nodes | Cloud IoT, web apps, video, audio |
Perhaps you want to consider a dedicated ESP as gateway, then you are not limited to a single wifi channel.
ie:
Where 1 is handling esp-now to wifi and the other is dedicated to esp-now
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That's a good suggestion - as I was trying work out how my Gateway could tell the Sender which WiFi channel to use. Your method means the 'esp-now to wifi' microcontroller could do a scan and pick the strongest AP (as I do with a number of my other nodes).
