The project aims to develop a smart home automation application using LPC 2148. using different sensors such as the rcwl-0516 microwave radar sensor and the optical infrared liquid level sensor, a smart home lighting system and an automatic water management system is developed respectively.
Using the rcwl-0516 microwave radar sensor we sense any external movement and upon successful detection we light up different LEDs to switch on the lights in the room. The sensor detects even in walled environment and hence can also be used in work spaces. The sensor gives logic high output in its out pin for a duration of 3 seconds upon successful detection. we raise an interrupt vector function in the LPC 2148 upon receiving this input from the sensor and send an output logic high to the LED for a duration of 15 minutes (15 sec used to test). this is implemented using the inbuilt timer in the LPC 2148. if a motion is detected within this logic high interval the timer is reset for another 15 minutes.
Using the optical infrared liquid level sensor we detect the total level of water in the tank and upon reaching the threshold an external signal is sent to cut off the power supply to the motor indicating full level in the tank. The Real time clock (RTC) of the 2148 is used to check the water level every 24 hours or 1 day (1 min used to test). If the level is below the threshold a logic high is sent to the pump to begin inflow of water in the tank until its filled. once the tank is filled the optical waterlevel sensor sends a logic low, which interrupts the LPC to switch off the pump.
the optical water level sensor although sends a binary value to the processor but its not digital. hence it was not possible to interface to the LPC 2148 using the GPIO pins. it was interfaced with the help of the inbuilt ADC.