Sonoff IW101 Power Monitoring Switch (IW101)
Sonoff IW101

Available from:


Install method:
USB to Serial

GPIO #Component
GPIO00 Button1
GPIO01 CSE7766 Tx
GPIO02 None
GPIO03 CSE7766 Rx
GPIO04 None
GPIO05 None
GPIO09 None
GPIO10 None
GPIO12 Relay1
GPIO13 LedLink
GPIO14 None
GPIO15 None
GPIO16 None
Configuration (old format, will be converted to new template when applied)
{"NAME":"Sonoff IW101","GPIO":[17,145,0,146,0,0,0,0,21,157,0,0,0],"FLAG":0,"BASE":41}
For more accurate energy consumption measurements this device requires power monitoring calibration.

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I think this is the first wall switch that support power monitoring using an ESP8266. It uses a Chipsea CS7598 chip for it, similiarly to the S31. The relay is rated to 16A 250V but Sonoff states max 15A incandescent or CFL load.

The single led on the front plate serves as power and connectivity indicator.

Back label Insides

The switchplate is removable and is held on only by a few plastic clips. Access to the internals requires unscrewing 4 screws. After removing them we see the main PCB with mains electricty, a wifi daughterboard soldered on to it and the touch pad board connected with a 6 pin header.


Serial Flashing

Necessary GPIO’s are neatly broken out on bottom left, albeit only on pads. To put the device into flash mode you need to ground GPIO0 using a wire to connect the two during boot (I recommend using a dupont wire on the header that connects to the switchplate). See image for pin locations.

Follow the standard flashing procedure and that’s it. Wiring