Bootloader mode¶

Heltec V4 has no CP2102 — put the board in download / bootloader mode before the web flasher.

Steps¶

Board stays plugged in over USB-C:

1. Hold USER (silk may also say PRG / BOOT).
2. Tap RST once.
3. Release USER.

USB re-enumerates briefly (Espressif 303a:1001 drops, then returns). On this desk the node came back as /dev/ttyACM0 with a new USB device number — the browser still loses the old handle, so reselect the Espressif / ttyACM* port in the flasher.

Confirm¶

After the button sequence:

esptool --chip esp32s3 --port /dev/ttyACM0 --before no-reset --after no-reset chip-id

Connected to ESP32-S3 on /dev/ttyACM0:
Chip type:          ESP32-S3 (QFN56) (revision v0.2)
Features:           Wi-Fi, BT 5 (LE), Dual Core + LP Core, 240MHz, Embedded PSRAM 2MB (AP_3v3)
…
Staying in bootloader.

If that connect fails, repeat the USER / RST / USER sequence, then reselect the port.

Alternate¶

Hold USER, plug in USB-C, then release USER. Same download mode.

Next: Flash firmware.