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3. Flash the firmware

Two binaries to flash, in this order:

  1. Each panel gets a bootloader, fuses, and the panel firmware (over a programmer)
  2. The controller gets the controller firmware (over USB serial the first time, then Wi-Fi after that)

After the very first flash, panels are updated over I²C from the controller — you only need a programmer once per panel.

Flash the panels

a. Burn the bootloader and fuses

Each panel needs the twiboot bootloader sitting in the upper flash region, plus the right fuse settings for the 16 MHz crystal. This is a one-time operation done with a USBasp connected to the panel's ISP header.

Don't guess the fuses

Setting fuses by hand is the single easiest way to brick an ATmega — wrong values can lock the chip out of further programming. Use the PlatformIO targets below; they're known good.

Pick the bootloader environment that matches your panel MCU:

Bash
# Fuses (also clears flash)
pio run -e atmega328p_bootloader -t fuses

# Burn the twiboot bootloader
pio run -e atmega328p_bootloader -t upload
Bash
pio run -e atmega328pb_bootloader -t fuses
pio run -e atmega328pb_bootloader -t upload

Repeat for every panel. The expected fuse values, where the bootloader lives in flash, and the OTA protocol it speaks are documented in Firmware → Hardware and Firmware → OTA & Updates.

b. Flash the panel application

Still over USBasp:

Bash
pio run -e panel_atmega328pb -t upload

The same binary works on both 328P and 328PB. The -D upload flag preserves the bootloader region on erase.

After the first flash, future updates are wireless

Subsequent panel updates do not require a programmer. Drop the new .bin into the app or hit POST /api/firmware/panels on the controller and it will reflash every panel one at a time. See Firmware → OTA & Updates.

Flash the controller

Plug the controller (ESP8266 or ESP32) into USB and pick the matching environment:

Bash
pio run -e controller_esp8266 -t upload
Bash
pio run -e controller_wemos -t upload
Bash
pio run -e controller_esp32 -t upload
Bash
pio run -e controller_s2_mini -t upload

Once Wi-Fi is configured (see the next step), the same command flashes over the network:

Bash
pio run -e controller_esp32 -t upload --upload-port lightnet-XXXX.local

where XXXX is the chip ID printed in the captive portal.

Quick sanity check

After flashing the controller, open a serial monitor at 57600 baud. You should see boot logs ending in something like:

Text Only
mDNS started: lightnet-XXXX.local
WebSocket: /ws
HTTP: :80

If you see that, the firmware is healthy. The next step is getting it on your network.

Next: First boot & Wi-Fi