11th week : The Keypad

Hello everybody,

Initially, we used a potentiometer to regulate the target value. We changed this one by a keypad because of the ergonomics and to define other option by using the letter A to D and the character * and #. The keypad has 8 connexions whose 4 entries (L1 to L4) and 4 exits (C1 to C4).



We use the Keypad library. Keypad.h is a library for using matrix style keypads with the Arduino.

Figure : Matrix keypad


We can add new functionalities to our project, for example, when you press the “A” key, it can show to the user the difference between the set point and the temperature who come from the sensor. If you press the “*” key, it will show the credits.

For now, we just have a minor problem, the main loop of your program wait until the user press a key, but we need the refresh your display to show the current temperature, so we need to find a solution. Maybe with the setHoldTime() function it will work. Have to wait to next week to try it out.

The final improvement of the assembly is the implementation of a security bottom. This one permit to prevent for example the intrusion of kids. To introduce a new order, we must have to push on this button to unlock the command during a few seconds.

Thanks for your reading,


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