Week-14 :- Input devices
This week assigment is to design an input device. I have used Atmega16u4 chip for this
task. This PCB have four Port B and five Port C, hence i am planning to use
these ports for this week assigment.
Passive Infrared (PIR) sensor
I am planning to use PIR sensor as the input device which can detect
any change in motion. PIR sensor details are shown below.
The initial plan was to use ATmega164u, since modified satshas kit is available now, I could use
the same. I have connected PIR sensor to the PIN D1 of the satshas kit. The output from the satshas kit
is used to drive a small relay. The relay have normal open and normal close connections. The Load can be connected
on normal open terminals, thus it act like a switch when charged. The energising pulse for the same is
send from atmega328p. The schematic of the relay is shown below. A few numbers of double pole double throw (DPDT) relay is available in fab lab, and
I have used the same for this project.
One port has been connected to PIR sensor along with the supply terminals. The second port is connected to
the 5v relay. This relay N/O is connected with the 240v, which act like a switch for the tubelight.
The connections were soldered and the same is shown below.
Once after assembly the unit is connected and tested. The video of the same is shown below.
The design files of the same can be downloaded here.
The PIR sensitivity is increased to maximum, it can detect the moving object within 4m. The timing is reduced to minimum level, but can be increased if require.
The satshas kit is powered from 9v battery through a 5v regulator. IC 7805 is used for regulation. For the simplicity, its connected across the battery terminals while testing.
The designing and the steps for realising the satshas kit is mentioned under week-16.