HeltecTM ESP32+Arduino Series Frequently Asked Questions


This page contains the most frequently questions from user. If this page’s detail can’t solve your problem, you can also talk in our forum: community.heltec.cn


Can’t Download Firmware

  • Use a better USB cable, or change a USB socket;

  • Check and make sure the CP210x drive had been correctly installed, users can refer to this document: Establish Serial Connection;

  • Press “PRG” button before upload.


Another Communication Bus Usage Example


System Reset All the Time


According to the situation we have collected so far, the most likely to cause a constant reset problem may have two reasons:

  • Power supply problem: please make sure the voltage of USB ≥ 4.7V, 300mA;

  • You chose an error board: because each type of board may have a different FLASH size, and they have a different partition map, it will cause the internal logic error.

Vext Control

The Vext is a power source for external devices. Refer from the schematic diagram, It’s controlled by GPIO21:


  • GPIO 21 --> LOW --> Vext(3.3V/250mA) ON

  • GPIO 21 --> HIGH --> Vext(3.3V/250mA) OFF