Bas BotBerg wanted to report the sensor data collected by the ESP32-C3 microcontroller on a portable Bluetooth thermal printer. Since there was no official interface other than the proprietary smartphone app provided by the manufacturer and the communication was undocumented, he set out to reverse-engineer the printer’s protocol. In such work, Bluetooth traffic is usually recorded while the app is running using Android’s debugging feature, and the file is examined in Wireshark to extract the commands. BotBerg, however, used a tool that listed the device’s Bluetooth Low Energy services and characteristics instead of the manufacturer’s software; he sent data to writable services and observed the responses. In his tests with Python and Bleak, he managed to run the motor and advance the paper. He then mapped the necessary data and endpoints and sent the same payloads from the ESP32 in C++. He also added the Adafruit GFX library to format the output and generate symbols. His code does not appear to have been published; open-source driver projects exist for similar inexpensive Bluetooth printers.
Why it matters
This work offers a practical response to the lack of an interface that would allow portable printers dependent on the manufacturer’s app to be used with different hardware. It particularly demonstrates the possibility of building an embedded setup instead of relying on phone-centered operation for developers who collect sensor data with an ESP32 and want to transfer the results to paper in the field. Moving the communication payloads validated in Python to a C++ environment shows that protocol knowledge can be adapted to a microcontroller application rather than remaining limited to experiments on a computer. Adding a graphics library allows the output to go beyond raw data transmission and be used for formatted reporting and symbol generation. However, the fact that the code has not been published leaves open the question of whether others can directly try the method and to what extent it will work with similar printers.
Background
ESP32 is not a new name in the FikirPilot archive: we have published 3 articles mentioning this name in the last 90 days; the most recent one is dated September 11, 2026.