W1209 digital temperature controller module is a low cost and highly functional thermostat module which is widely used in automation projects. W1209 thermostat module includes a seven segment LED display and a NTC waterproof temperature sensor. There are 3 switches (SET, + and -) on board to set temperature and other parameters like turning on trigger temperature. W1209 module has an integrated microcontroller in it but does not requires programming knowledge. There is an onboard relay which acts as a switch to the load connected to it. A maximum load of 240V AC at 5A or 14V DC at 10A can be connected to the on board relay. Measurement and control accuracy of the circuit is 0.1 C. Temperature control range for the module is -50 C to 110 C. 0.5 seconds is the refresh rate of the W1209 module.

Displaying the current temperature
The thermostat will display the current temperature in C by default. When in any other mode making no input for approximately 5 seconds will cause the thermostat to return to this default display.
Setting the trigger temperature.
To set the trigger temperature, press the button marked SET. The seven-segment display will flash. You can now set a trigger temperature (in C) using the + and – buttons in 0.1 increments. If we dont press any buttons for approximately 2 seconds, the trigger temperature will be stored, and the display will return back to the current temperature.
Setting the parameters
To set any parameter, first long-press the SET button for at least 5 seconds. The seven-segment display should now display P0. This represents parameter P0. Pressing the + or – buttons will cycle through the various parameters (P0 to P6). Pressing the SET button whilst any of these parameters are displayed will allow you to change the value for that parameter using the + and – buttons. When finished setting a parameter, press the set button to exit that option. If no buttons are pressed for appro