|| || | Demonstrates changing the keypad size and key values. LiquidCrystal lcd ( 7, 8, 9, 10, 11, 12 ) LiquidCrystal lcd (A0, A1, A2, A3, A4, A5 ) bool doInitilizeLCD = true // -KEY PAD START. #include // initialize the library with the numbers of the interface pins This example code is in the public domain. Library modified by Limor Fried ( ) Example added by Tom Igoe Wiper to LCD VO pin (pin 3 ) Library originally added by David A. LCD RS pin to digital pin 7 LCD Enable pin to digital pin 8 LCD D4 pin to digital pin 9 LCD D5 pin to digital pin 10 LCD D6 pin to digital pin 11 LCD D7 pin to digital pin 12 LCD R/W pin to ground This sketch prints "Hello World!" to the LCD There are many of them out there, and youĬan usually tell them by the 16-pin interface. Library works with all LCD displays that are compatible with the The systems make the assumption that the user know to either choose the # button to signal the end the input and submit the code.ĭemonstrates the use of a 16x2 LCD display. The design of the UI was modeled after keypad entry systems which generally do not have a way to view the code entered. The # key is used to send the key for evaluation while the * key will reset the input. The key is hardcoded in a variable, but could be changed by the user in later enhancement iterations to the design. To disable the system, a 4 digit key code is entered. The buzzer volume is adjustable via a rotary potentiometer. The handleBuzz() function acts to change the frequency of the buzzer which can be adjusted by changing the check value of the buzzCycleCounter. The alarm() function checks if the device is armed, when armed and when motion is detected the active buzzer is turned on and a red LED is lit. When armed, the devise polls the output from the PIR sensor to detect movement. On start up, the LCD indicates that to arm the system press the * key. This includes arming and disarming the system and making programming changes. An LCD with adjust brightness and contrast via a potary potentiometer indicates the state of the system and allows the user to see the input of the membrane keypad. An alarm keypad is used as a way of controlling an alarm system. When the device is powered it is initialized in the disarmed state. All libraries are standard for the components. The libraries required are available for download in zip format from Elegoo here or they can be downloaded from online by searching for the component libraries online. The usual hello world blinky LED code in this case is insufficient. The keypad must be capable of sending input signals, the LCD screen must refresh and the LED indicator must switch off and on all without blocking. I undertook this project to gain more experience with coding more complex embedded projects that require the use of state machine programming.
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