Nano ESP32 BLE Scanner




About: Make it yourself if you cannot buy one!

This instructables show how to use ESP32 to make wireless BLE signal scanner, all scanned data will send to the HTTP server via WiFi.

Step 1: Why BLE Scanner?

BLE (Bluetooth Low Energy) signal is very common for current digital device, mobile phone, wrist band, iBeacon, assets tag. This signal not only help you pair up the devices, it also can report the device status, such as battery level, heart rate, motion (walking, running, falling), temperature, panic button, anti-loss ... etc.

It is a valuable big data for location tracking if we can collect the BLE signal at certain number of position.

In long run, the BLE scanner should fix in selected position. However, selecting a right place require trial and error. A tiny wireless BLE scanner is handy to help you check where is the right place.

Step 2: Preparation

ESP32 board

I am using ESP-WROOM-32 board this time.

A Tiny Container

Any small container should be ok, I have some tiny TicTac box in hand and it just fit an ESP32 board in it, what a coincidence!

Lipo Battery

ESP32 peak current is around 250 mA. For not drawing over 1C current at anytime, Lipo Battery should over 250 mAh capacity. 852025 is the maximum size that can fit into the Tictac box and it claim it have 300 mAh, it's good enough.

Power Regulator Circuit

A 3.3 V LDO regulator, some capacitors, I have some HT7333A regulator, 22 uf and 100 uf capacitor in hand


A 10k Ohm SMD resistor for pull up EN pin, a small piece of multi purpose PCB, a power switch, some coated wires, 7 pins header

ESP32 Dev Dock

In program process, it also require a ESP32 Development Dock, you may find how to make it in my previous instructables:

Step 3: Trim the PCB

Measure the dimension of your tiny container and trim the PCB to fit into it.

Step 4: Soldering Pin Header

Let's start soldering work from the 7 pins header and PCB.

Step 5: Soldering Power Circuit

Here is the connection summary:

LDO Vin  -> Vcc pin header(1) -> power switch -> Lipo V+, Charge pin header(7)
LDO GND  -> GND pin header(2), capacitors V- pins, ESP32 GND
LDO Vout -> capacitors V+ pins, ESP32 Vcc

Step 6: Soldering Pull Up Resistor

It is the most difficult soldering work in this project, the pin width in ESP32 board is only 1.27 mm. Fortunately, Vcc and EN pin is nearby, it can direct soldering resistor between both pin without wire.

ESP32 Vcc pin -> 10k Ohm resistor -> ESP32 EN pin

Step 7: Soldering Program Pins

Here are the connection summary:

Tx pin header(3)      -> ESP32 Tx pin
Rx pin header(4)      -> ESP32 Rx pin
Program pin header(5) -> ESP32 GPIO 0 pin
RST pin header(6)     -> ESP32 EN pin

Step 8: Cleaning Up the TicTac Box

  • Eat all sweets
  • Remove the stickers

Step 9: Squeeze Into the Box

Squeeze all component into the TicTac box, be careful don't tear off any wires.

Step 10: Prepare Software

Arduino IDE

Download and install Arduino IDE if not yet:


Install hardware support for ESP32

Detailed instructions for installation in popular operating systems.

For Linux: (see also the Arduino playground page

For macOS X:

For Windows:


Step 11: Program the ESP32



#define POST_URL "http://YOURSERVERNAMEORIP:3000/"
  • Select Board: Any ESP32 board
  • Select Partition: No OTA / Minimal SPIFFS
  • Upload

Step 12: Receive Data

If you are not yet have any HTTP server to receive the POST data, you may try to use this simple Node.js program:

Here are the sample data received:

Tue Mar 20 2018 08:44:41 GMT+0000 (UTC): [


  "Address": "6e:3d:f0:a0:00:36",

  "Rssi": -65,

  "ManufacturerData": "4c0010050b1047f0b3"



  "Address": "f8:04:2e:bc:51:97",

  "Rssi": -94,

  "ManufacturerData": "75004204018020f8042ebc5197fa042ebc519601000000000000"



  "Address": "0c:07:4a:fa:60:dd",

  "Rssi": -96,

  "ManufacturerData": "4c0009060304c0a80105"



Step 13: Power Measurement

The program scan BLE signal for 30 seconds, then deep sleep 300 seconds and then scan again. For each loop, it consume around 3.9 mWh.

Theoretically, it can run: (I will update the testing result later on my Twitter)

300 mAh Lipo / 3.9 mWh @ 330 seconds

= [(300 mA * 3.3 V) mWh / 3.9 mWh * 330] seconds

~83769 seconds

~23 hours

2018-04-08 Update:

I have changed to use XC6503D331 LDO regulator and made 2 measurements:

Round 1: 12:43:28 - 16:42:10 (~20 hours) 210 BLE scan POST received

Round 2: 10:04:01 - 05:36:47 (~19.5 hours) 208 BLE scan POST received

Step 14: Happy Scanning!

It time to find a place to setup you BLE tracking network!



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    28 Discussions


    5 days ago

    Thank you for sharing this project.
    I have sole BLE beacon sending temperature and humidity value in the services can I get those values with your Arduino program? At the moment you only get rssi, manufacturer data and address.
    Thank you,


    4 weeks ago

    i also did the same you did,i am using esp wroom32 form lolin32 development board.
    i connected sd card reader with that board and i programming using arduino.
    my project is it scans the nearby ble devices and store the datas with time form the server(NTP) and store those values in txt file in sd card and after some time the txt file is send to the server..i completed in development board.
    now how to repeat the same in custom pcb??.
    can you please help me

    10 replies

    Reply 4 weeks ago

    Hi mohandhanush25, did you encounter any problems while following my steps?


    Reply 4 weeks ago

    can you please tell me how to program wroom32 module with arduino using usb to ttl connector


    Reply 4 weeks ago

    Simply follow the dev dock circuit can program ESP32.


    Reply 4 weeks ago

    ok after this setup,will the separate wroom32 module works like a development board, can i connect sd card read with miso,mosi pins of wroom32,will it work??


    Reply 4 weeks ago

    I never tried connect SD card myself, but I have tried M5Stack, ESP32 should work with SD well.


    Reply 4 weeks ago

    after this setup, can i connect sd card module directly with wroom32 pins of miso,mosi. will it work the same way which worked in development board??


    Reply 4 weeks ago

    ok without dev dock. can i program wroom32 module with arduino??


    Reply 4 weeks ago

    dev dock only a simple circuit connect DTR and RTS to GPIO 0 and reset pins. If you insist don’t like connect this circuit, simply pull down GPIO 0 manually and then reset ESP32 to enter program model before you press upload in Arduino IDE.


    4 months ago

    Thank you very much for this! It works fine at first, but after a few hours it stops posting data, and only prints this repeated on the serial console until I power cycle:

    Task watchdog got triggered. The following tasks did not reset the watchdog in time:
    - IDLE (CPU 0)
    Tasks currently running:
    CPU 0: wifi
    CPU 1: IDLE

    1 reply

    Reply 4 months ago

    I guess it stucked at connecting WiFi...


    8 months ago

    I am having issues with the Arduino sketch being too big. I am using Arduino IDE V1.8.5 on windows 10. Here is the error message I receive. Can you help?

    "Sketch uses 1357670 bytes (103%) of program storage space. Maximum is 1310720 bytes.
    Global variables use 72828 bytes (24%) of dynamic memory, leaving 222084 bytes for local variables. Maximum is 294912 bytes.
    Sketch too big; see for tips on reducing it.
    Error compiling for board ESP32 Dev Module."

    3 replies

    Reply 8 months ago

    okay, I didn't follow step 10. Once I did I did receive a different error...."Error at line 7: CSV flag column contains unknown flag
    '</p>'". Once I removed the </p> from the same line it all worked fine. I am working on the HTTP server connections next so please disregard my earlier comment- you did a great job here!!


    Reply 8 months ago

    Hi billp119,
    Yes step 10 is very important, thats why I need clone the main branch and amend it.