Wireless Modules

Wireless modules connect a project to a phone, another board or a network, with no cable.

  • The HC-05 Bluetooth module is a transparent serial bridge. A phone app's bytes arrive on its UART pins as if typed into the Serial Monitor.
  • The HM-10 adds Bluetooth Low Energy (BLE) to boards that do not have it.
  • The nRF24L01 is a cheap 2.4GHz radio for board-to-board links.
  • LoRa modules trade speed for range. They send small, infrequent messages over long distances on very little power.
  • The SIM800 adds SMS and mobile data.
  • Built-in alternatives: an ESP32 already has Wi-Fi, BLE and ESP-NOW, a direct peer-to-peer link between ESP32 boards with no router.

How to choose:

  • Pick Bluetooth for phone control.
  • Pick ESP-NOW or an nRF24L01 for board-to-board links.
  • Pick LoRa for long range.
  • Pick GSM where there is no Wi-Fi.

Check the module's logic voltage before wiring. Many radios are 3.3V parts, which suits the ESP32 but may need level shifting on a 5V Arduino.

Frequently asked questions

Bluetooth Classic or BLE?

BLE for battery devices sending short readings. Classic for a continuous serial stream to a laptop or older app.

How far does LoRa reach?

Kilometres in good conditions, for small, infrequent messages. It is not for large data.

Do I need a module with an ESP32?

Often not. It has Wi-Fi, BLE and ESP-NOW built in. Add LoRa or GSM for long range or no Wi-Fi.

What is ESP-NOW?

A direct peer-to-peer protocol between ESP32 boards, with no router and no pairing.

Guides

Reference pages on soldr.ai

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