Flashing Your Device¶

Download the latest release from GitHub Releases and flash your ESP32 over USB. You only need to do this once — after that you can update over WiFi.

What's in a Release¶

Each release ships three binaries:

File	When to use
`sqmeter-complete-flash-vX.Y.Z.bin`	Fresh ESP32 — everything in one file
`sqmeter-firmware-vX.Y.Z.bin`	OTA update via web UI
`sqmeter-littlefs-vX.Y.Z.bin`	Web UI update only

For a brand-new device, you only need sqmeter-complete-flash-*.bin.

Prerequisites¶

Install esptool:

pip install esptool

Fresh Flash (Recommended for New Devices)¶

One command, one file. Flashes bootloader, partition table, firmware, and web UI filesystem all at once:

esptool.py --chip esp32 --port PORT --baud 115200 \
  write_flash 0x0 sqmeter-complete-flash-v0.0.1.bin

Replace PORT with your serial port:

macOS / LinuxWindows

/dev/cu.usbserial-*   # macOS
/dev/ttyUSB0          # Linux

COM3

Finding your port

esptool.py --chip esp32 chip_id

esptool will scan and print the detected port.

Standard or Bluetooth build?¶

Each release has two builds:

Build	Files	Choose it if
Standard	`sqmeter-complete-flash-.bin`, `sqmeter-firmware-.bin`	You don't need Bluetooth - recommended
Bluetooth	`sqmeter-ble-complete-flash-.bin`, `sqmeter-ble-firmware-.bin`	You want the phone alarm or BLE broadcasts (Bluetooth)

The Bluetooth build uses a different partition layout, so the first install has to be a USB flash of sqmeter-ble-complete-flash-*.bin at 0x0, as above. After that it updates over the web UI like the standard build. Going back to the standard build is also a USB flash.

Selective Updates (Existing Devices)¶

Prefer OTA updates from the web UI — no cable needed. But if you need USB:

Firmware only¶

esptool.py --chip esp32 --port PORT --baud 115200 \
  write_flash 0x10000 sqmeter-firmware-v0.0.1.bin

Web UI filesystem only¶

esptool.py --chip esp32 --port PORT --baud 115200 \
  write_flash 0x310000 sqmeter-littlefs-v0.0.1.bin

On the Bluetooth build the firmware goes to 0x10000 too, but the web UI filesystem lives at 0x380000.

NVS is safe

Firmware and filesystem updates never touch the NVS partition where your WiFi credentials and settings are stored.

Flash Memory Map¶

Partition	Offset	Size	Contents
nvs	`0x9000`	20 KB	WiFi credentials, settings
otadata	`0xe000`	8 KB	OTA boot slot indicator
app0	`0x10000`	1.5 MB	Firmware
app1	`0x190000`	1.5 MB	OTA update slot
spiffs	`0x310000`	512 KB	Web UI (LittleFS)