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Nanxin NX-SM400 Power Monitoring Plug

BR
Nanxin NX-SM400

Available from:
Aliexpress.com



Manufacturer:
Alibaba.com

Flashed with:
Tuya-Convert

GPIO #Component
GPIO00 None
GPIO01 None
GPIO02 None
GPIO03 Button1
GPIO04 BL0937 CF
GPIO05 HLWBL CF1
GPIO09 None
GPIO10 None
GPIO12 HLWBL SEL
GPIO13 Led1
GPIO14 Relay1
GPIO15 None
GPIO16 None
FLAG None

Template

{"NAME":"NX-SM400","GPIO":[0,0,0,17,134,132,0,0,130,52,21,0,0],"FLAG":0,"BASE":18}
For more accurate energy consumption measurements this device requires power monitoring calibration.

This is the english version

Para a versão em português (pr-BR) use ESSE LINK

Recently, some smart plugs with the BR plug type started appearing on AliExpress

Usually, these products don’t have a specific model and make, since they are mostly Tuya whitelables. After searching alot, I’ve found Nanxin NX-SM400 which looks like this one.

Flash Tasmota

Since this model working with the Smart Life app, we know it uses a Tuya chip. To flash Tasmota, we need to us tuya-convert. There’s an excellent tutorial (in pt-BR) by Douglas Baptista that you can use.

Configuring Tasmota

To configure the smart plug on Tasmota, we have to know how the ESP pins are connected. I had to open mine to check the connections. But you don’t have to do the same. You can use this template that I’ve created.

Go to the device’s IP address > Configuration > Configure Other > Template

{"NAME":"NX-SM400","GPIO":[0,0,0,17,134,132,0,0,130,52,21,0,0],"FLAG":0,"BASE":18}

Just paste that line and check Activate

Teardown

To create the template, I had to open the plug up.

If you want to do that, you can use a hot air gun on the bottom part and a flat head screwdriver to force it open. It will probably damage the case a little bit and you will need to glue it shut.

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The smart plug uses the TYWE2S Tuya chip, which is a ESP8285.

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The power monitoring chip is the BL0937 It’s pins are connected like this:

BL0937 ESP8285
Pin 6 (CF) GPIO 4
Pin 7 (CF1) GPIO 5
Pin 8 (SEL) GPIO 12

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The switch and LEDs are on another PCB. They are connected like this:

PCB ESP8285
Red LED GPIO 14 (Same as Relay)
Blue LED GPIO 13
Switch GPIO 3 (Rx)

At last, the Relay is connected to the GPIO14 pin.