WiFi Teardown – arVin Light Switch
This post is the first in what I hope will be a very fun and informative series. Lately there has been a huge influx of cheap wifi enabled IOT/SmartHome devices flooding the market. Each with their own (usually questionable) app.
I have embarked on an exciting journey to find out how many of these devices contain friendly micro controllers, and write basic “snoop-free” firmware replacements!
Price (at time of post): $25.99
Dual color LED (Red and Green)
Relay: Golden brand 15A @ 120V
Flash Size: 1MiB
Relay/Red LED: Pin 12
Green LED: Pin 13 (inverted)
Button: Pin 0 (inverted)
[env:arvin] platform = espressif8266 board = esp01_1m framework = arduino board_build.flash_mode = dio
This device is actually very easy to reprogram, hook up the exposed programming header labeled to a USB -> TTL Serial converter using the following table.
Serial -> Device
GND -> GND
3V3 -> 3V3
RX -> TX
TX -> RX
Put the device into boot mode by holding down the button while powering up the device, then you can use esptool or arduino uploader as normal.
I have included a basic firmware that includes ArduinoOTA and WiFiManager for your hacking pleasure on Github
These are the http endpoints of this basic firmware
http://<device ip>/ will show the name of this device and status of device
http://<device ip>/led/on will turn the Green LED on
http://<device ip>/led/off will turn the Green LED off
http://<device ip>/relay/on will turn the Red LED and Relay on
http://<device ip>/relay/off will turn the Red LED and Relay off
Note: Pressing the button on with this firmware will not work until you connect to the wifi labeled “esp_<chipid>” and set up the wifi
Note: Pressing and holding the button for 5 seconds will clear the stored wifi credentials and restart the device.
If you have any suggestions of what I should tear down next let me know in the comments!
Please let me know if this format is informative enough for you!