Skip to main content

Heltec LoRa Board Common Issues

This page covers the most frequent problems with Heltec LoRa32 V2/V3 boards.

Display Not Working​

Symptom: OLED stays black after flashing.

Causes and fixes:

  1. Wrong board variant selected — V2 and V3 use different pin mappings. In Arduino IDE, V3 needs Heltec WiFi LoRa 32(V3), not V2.
  2. Display not initialized in code — Meshtastic auto-detects, but custom Arduino sketches need explicit init:
#include <U8g2lib.h>
U8G2_SSD1306_128X64_NONAME_F_HW_I2C u8g2(U8G2_R0, U8X8_PIN_NONE);
void setup() { u8g2.begin(); }
  1. Loose OLED connector — The OLED is connected via a delicate FPC ribbon. Re-seat it gently.

LoRa Not Transmitting​

Symptom: No packets seen on other nodes or gateway.

  1. Check frequency — EU (868 MHz) vs US (915 MHz) vs CN (470 MHz). Must match your hardware antenna.
  2. Check antenna — Heltec boards ship without antenna. You must attach one. Running without antenna can damage the radio.
  3. Check power — Some USB ports supply insufficient current during TX bursts (peak 120mA). Use a powered hub or battery.

Battery / Power Issues​

Symptom: Board resets or brownouts during LoRa transmission.

  1. V3 needs external battery — USB alone may not supply enough peak current. Connect a 3.7V LiPo to the JST connector.
  2. V2 battery connector polarity — The V2 JST connector is reversed compared to most LiPo batteries. Double-check polarity before connecting.

USB Not Recognized​

Symptom: No COM port appears when plugged in.

  1. Install CP210x driver — unlike CH340, Heltec V3 uses Silicon Labs CP2102. Download from silabs.com.
  2. Bad USB cable — many micro-USB cables are charge-only. Try a known data cable.
  3. Hold BOOT while plugging in — if the board is stuck in a crash loop, force bootloader mode.

GPS Not Getting Fix (T-Beam only)​

Symptom: GPS shows 0 satellites or no fix.

  1. First fix takes 5–15 minutes with clear sky view. Be patient.
  2. Indoor = no signal — GPS needs sky visibility. Move outdoors.
  3. Antenna connected? — T-Beam needs the external GPS antenna screwed in.
Still stuck?

Post your issue on the Community Forum with your device model, what you tried, and a photo of your setup.