Product Description

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I. Overview 
The 5V ESP8266 four-way WIFI relay module uses the ESP-01 as a WIFI module, with a mature and stable 8-bit MCU chip. It can realize the wireless control of the 4-way relay using the mobile phone APP within the LAN in a simple configuration process. 
Second, functional characteristics 
1, Onboard high performance microprocessor and ESP-01 WIFI module; 
2, the module has 2 working modes: 
Mode 1: The mobile phone is directly mounted on the WIFI module; 
Mode 2: The mobile phone and WIFI module are loaded on the router at the same time; 
Additional features: It can also be used as a USB relay when the ESP-01 is unplugged.

3, transmission distance:
(1) In the open environment, the maximum stable transmission distance when the mobile phone is mounted on the WIFI module is 100m;
(2) When the WIFI module and the mobile phone are mounted on the router at the same time, the transmission distance is strong according to the signal of the router.
Weak and certain.

4. Use Smartconfig technology to complete the configuration of the ESP-01 WIFI module account and password on the mobile phone APP. The configured account and password have the power-off memory function.

5, On-board 12V, 10A/250V AC 10A/30V DC relay, can continuously suck 100,000 times, with diode escaping protection, short response time;

6, onboard mode selection and real-time working status indicator;

7, with 4 optocoupler isolation, strong anti-interference ability;

8, reserved UART debug interface and MCU program download interface.

Third, hardware introduction and explanation
Board size: 60*63mm
Board function description:
1, onboard resources:
IN+, IN-: 12V power input;
5V, GND, TX, RX:UART serial port pin;
SWIM, PIN8, NRST: Reserved MCU program download port.
Button S1: Mode switch, default is mode 1
Press key S2: restore factory settings
LED D1/D2/D3/D4 (red light): Relay operation indicator lighted when turned on
LED D7 (red): Mode 1 indicator
LED D5 (blue light): Mode 2 indicator
LED D6 (green light): Operating status indicator, described as follows:
(1) When it goes out, it means that it is self-configuring or losing connection with the router;
(2) When 0.5S is flashing, it means waiting for the mobile phone APP to configure the WIFI account and password for the ESP-01 module;
(3) When the 2S flashes slowly, it means that the configuration is completed, waiting for a TCP connection with the handset;
(4) When it is always on, it means that it establishes a TCP connection with the handset.

Reserved 2 jumper caps: Please plug in the bottom end when using normally (ie RX connects RX1, TX connects TX1). If yo