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Shelly Plug S Gen3

← README · All devices · Commands

State: confirmed Generation: 3 Chip: ESP32-C3

🧰 Before you start · ⚙️ Config · 📍 Pins · ⚡ Flash it · 👀 What to expect · ↩️ Way back

Fact Value
Profile PlugSG3
Flash 8 MB
Official package 2.1.0 (stable since 2026-10-14; Bootloader, partition table and filesystem are the same as in 2.0.1; the hardware runs were made with 2.0.1)
Partition table 0x10000
App slot size 0x2a0000
ESPHome device page Shelly Plug S Gen3

Note

Confirmed: the whole chain ran on a real device. The package route was confirmed with a minimal config (Wi-Fi, API and OTA only): send with --esphome-factory ran and ESPHome runs. The owner also runs the full ESPHome device-database config (relay, metering, LED) on these plugs.

Before you start

Check first:

  • the device runs Shelly's own firmware, not ESPHome yet
  • you know its IP address (--ip), or this PC is on the device's own access point (default 192.168.33.1)
  • the device can reach this PC: same network, port 8000 (--port) not blocked
  • your ESPHome config uses the partition table below and is compiled
  • a UART adapter is at hand as your way back (Recovery over UART)

ESPHome config

Important

build refuses a config without Shelly's partition table. Copy partitions/PlugSG3-stock.csv from this repository next to your YAML and keep CONFIG_PARTITION_TABLE_OFFSET: "0x10000".

esp32:
  variant: ESP32C3
  board: esp32-c3-devkitm-1
  flash_size: 8MB
  partitions: PlugSG3-stock.csv        # copy from partitions/ in this repository
  framework:
    type: esp-idf
    sdkconfig_options:
      CONFIG_PARTITION_TABLE_OFFSET: "0x10000"
    advanced:
      enable_ota_rollback: false

ota:
  - platform: esphome
    allow_partition_access: true

Tip

Start from the config on the ESPHome device page (relay, BL0942 metering, temperature, LED, button) and replace its esp32: block with the one above.

Pins

Function Pin
Relay GPIO4
Button (pull-up, inverted) GPIO18
BL0942 power meter (UART1, 9600 baud) ESP RX GPIO6, ESP TX GPIO7
Internal temperature (NTC) GPIO3
LED: addressable, WS2812, 4 pixels GPIO5

Source: the owner's config on the ESPHome device page, which the owner runs on real plugs. The firmware agrees: it sets up UART1 with RX 6 / TX 7, a button on GPIO18 and an RMT LED on GPIO5 with 4 pixels.

Note

The device database labels GPIO6 "BL0942 TX" and GPIO7 "BL0942 RX". That is the BL0942's point of view: in ESPHome, rx_pin is GPIO6 and tx_pin is GPIO7.

Flash it

  1. Install the requirements (once):
pip install -r requirements.txt
  1. Fetch the official package:
python ota.py fetch PlugSG3 --insecure
  1. Build: put your app into it; the ZIP goes to out/:
python ota.py build PlugSG3 app.ota.bin --esphome-factory app.factory.bin --esphome-yaml app.yaml
  1. Check the device first. Nothing is sent:
python ota.py send PlugSG3 out/PlugSG3-app-<date>.zip --ip <device IP> --dry-run
  1. Flash it (the log goes to a file with --log-file):
python ota.py send PlugSG3 out/PlugSG3-app-<date>.zip --ip <device IP> --log-file

app.ota.bin and app.factory.bin are the two files ESPHome compiles. --dry-run only checks the device and, for this package, reads the update target slot. Command reference: Commands.

What to expect

send shows these lines at the default log level, in this order:

# Log line Meaning
1 Update target slot: 0 ... The slot check of send. Anything else: run python ota.py restore PlugSG3 first
2 Device: The bootloader will be replaced ... (raw log: Boot: cur ... min ... update? 1) The installer will write ESPHome's bootloader. WARNING: ESPHome's bootloader was NOT written (update? 0) means it will not: build again with a higher --boot-min-version (why)
3 The progress (Update: ... %, one line that updates in place) up to 100 %, then Done: update installed, the device confirmed it The device restarts into ESPHome

Notes for this device

  • The profile sets boot_min_version: 1.0.9. The official 2.0.1 package carries the same bootloader as the Plug M Gen3 package (the files are byte-identical), which reports Shelly OS loader 1.0.3 once installed. A plug that already runs it (restored from the package, or shipped with it) would skip the default 1.0.3, and later ESPHome OTAs would not take effect. The run on a real Plug S Gen3 used the default and the plug had loader 1.0.2; the change is not run on a Plug S Gen3 yet. Check the --watch log for Boot: cur ... update? 1.

Way back

python ota.py restore PlugSG3 sends the official firmware back while Shelly firmware still runs.

Warning

  • Wipes Wi-Fi and settings. ESPHome opens its own access point or joins the Wi-Fi from your config; if nothing comes up, power-cycle the device (help).
  • No way back over the network once ESPHome's bootloader runs: restore gets no answer, only UART brings Shelly OS back (Recovery over UART). Take a flash backup first if you can.
  • Flashed it? Tell us, also when it worked: open a device report.

Bootloader and slots · Troubleshooting · Recovery over UART