Heltec V3/V4-class boards use the ESP32-S3's native USB-Serial-JTAG
peripheral (no discrete USB-UART bridge chip), which resets the chip on a
DTR/RTS transition — the same mechanism esptool uses to force bootloader
entry. The Meshcore/Meshtastic/RNode serial probes all open the port with
library defaults (DTR/RTS asserted), so each probe attempt was likely
rebooting a real, correctly RNode-flashed Heltec board mid-handshake,
surfacing as an endless "No supported mesh radio found" retry loop.
Deassert both lines immediately after open and let the board settle before
writing, in all three probe paths.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
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