Rivr Firmware – relay_rak4631 (nRF52840)
===============================

Files in this package
---------------------
  rivr_relay_rak4631.hex          Intel HEX for J-Link / nrfjprog
  rivr_relay_rak4631_dfu.zip      adafruit-nrfutil DFU package (serial bootloader)
  rivr_relay_rak4631.uf2          UF2 image for USB-drive drag-and-drop flashing
  rivr_relay_rak4631.json         Metadata
  flash.sh                    Linux/macOS flash script

Flashing – UF2 drag-and-drop (simplest)
----------------------------------------
  1. Double-tap RESET – device mounts as a USB drive (T1000-E-BOOT etc.)
  2. Copy rivr_relay_rak4631.uf2 onto the drive – done!

Flashing – adafruit-nrfutil / serial bootloader
------------------------------------------------
  1. Install: pip install adafruit-nrfutil
  2. Double-click RESET to enter the serial DFU bootloader.
  3. chmod +x flash.sh && ./flash.sh /dev/ttyACM0

Flashing – J-Link / nrfjprog
-----------------------------
  nrfjprog --program rivr_{variant}.hex --chiperase --reset

Support
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  https://github.com/MichTronics/Rivr
