You can use an M5Stack Core ESP32 and Visuino to scan for nearby Bluetooth Low Energy (BLE) devices and show discovered devices on the board’s screen. The scan detects devices that are broadcasting BLE advertisements; it does not automatically connect to them, pair with them, or read their data. The tutorial demonstrating this build was published on June 20, 2023, and does not establish a universal scan range or device limit.
What you need for the M5Stack Bluetooth scanner
- M5Stack Core ESP32 development kit: This is the scanner platform used in the tutorial. Check the exact board revision: the original Core/Gray ESP32 is not the same hardware target as Core2 or CoreS3.
- A computer and compatible USB cable: These are practical setup items; the tutorial description does not specify a particular cable model.
- Visuino: The tutorial uses this visual development environment to build the scanner.
M5Stack’s Core/Gray documentation describes an ESP32 development kit with Wi-Fi, 4 MB SPI flash, dual-core operation, and Arduino IDE support. Those are board characteristics, not a guarantee that every M5Stack product or revision uses the same hardware.
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How the scan finds Bluetooth devices
A passive BLE scan listens for advertising packets sent by devices in radio range. Devices that are not advertising, or whose packets the scanner does not receive, will not necessarily appear. Nearby interference, obstacles, the devices’ advertising behavior, and scan configuration can all affect what is discovered.
The tutorial shows scan results on the M5Stack display, but reports no universal range, maximum device count, latency, or accuracy figure. Treat the display as a view of devices observed during that scan, not an exhaustive inventory of every Bluetooth device nearby.
#1 Best Overall
- Powerful ESP32-S3 Chip: The M5Stack CoreS3 is powered by the advanced ESP32-S3 chip, offering improved performance and enhanced capabilities for IoT projects.
- Built-in Wi-Fi and Bluetooth: The CoreS3 comes with built-in Wi-Fi and Bluetooth connectivity, allowing seamless wireless communication and integration with other devices.
- Integrated Camera Interface: This development board features an integrated camera interface, enabling users to easily connect a camera module for capturing images or implementing computer vision applications.
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Scanning, connecting, and pairing are different steps
| Operation | What it does | Does it require pairing? |
|---|---|---|
| Passive BLE scanning | Receives advertising packets from devices that are broadcasting. | No. Observing advertisements does not itself require pairing. |
| GATT connection | Connects to a device to interact with its services and characteristics. | Not necessarily; requirements depend on the device and the data or operation involved. |
| Protected GATT access | Exchanges data or performs operations protected by the device’s security settings. | Authentication or other BLE security procedures may be required. |
Espressif’s ESP-IDF multi-connection example lays out a broader workflow: initialize the system, configure scanning, discover devices, connect to selected devices, and register for notifications. It demonstrates an ESP32 central device working with three peripherals; that example is not a scan-capacity guarantee for the M5Stack/Visuino build.
Development options beyond the demonstrated Visuino build
Visuino is the workflow used in the tutorial. Developers building their own scanner may instead use Arduino or ESP-IDF, but those are separate implementation paths rather than steps required to reproduce the demonstrated project.
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Espressif’s Arduino BLE documentation distinguishes the original ESP32 Arduino core’s Bluedroid stack, which supports Bluetooth Classic and BLE, from NimBLE, a BLE-only stack with lower flash and RAM requirements. The appropriate stack depends on the application; a passive BLE scanner does not need Bluetooth Classic simply because the board can support it.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Saving scan results to a MicroSD card
The tutorial’s screen display is not the same as persistent logging. For a more advanced implementation, the open-source ESP32-BLECollector project describes a passive BLE scanner with a user interface that stores discovered data in SQLite on an SD card.
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- RFID & ALERT INTERACTION: WS1850S RFID (13.56 MHz, ISO/IEC 14443 Type A/B), 80dB buzzer, RTC and under-screen buttons – enable access control, timed alerts, and device wake-up functions.
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That project documents requirements of an ESP32-WROOM or WROVER, an SD card, FAT32 MicroSD up to 4 GB, and a 320×240 display. It also warns that BLE and SQLite libraries consume substantial memory and recommends using a large application partition scheme. These requirements describe that project, not the basic M5Stack/Visuino tutorial; confirm hardware and library compatibility before adapting it to a Core board.
Quick Recap
What this scanner can—and cannot—tell you
- It can show BLE devices whose advertisements the scanner receives during its scan.
- It does not, through scanning alone, reveal protected GATT data or establish a connection.
- A missing device is not proof that the device is absent; it may not be advertising or its packets may not be received under the current radio conditions.
- The cited tutorial does not provide a tested range, device limit, or timing benchmark, so results should be evaluated in the environment where you plan to use the scanner.
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