- Letter box system is actually an indicating system, it shows indications whenever there arrives latter in the letter box.
- It works using on the concept of Obstacle detection. In this arrangement IR Transmitter & IR Receiver are placed near to each other whenever any obstacle (Letter in our case) comes in front if this arrangement the rays gets reflected and thus we get the output as HIGH.
- Thus we have detected the Letter in the Box.
Step 1: Parts
You will need the following parts for building the Smart Letter Box:-
1. Arduino Board
2. Obstacle Sensor Module.
3. A Regular Letter Box.
4. An LED Module.
5. SIRC Remote Control (To Reset the Box)
6. TSOP (To Receive the IR Signals)
You can Buy these Parts from HERE !
Step 2: Arrangement & Connections.
Stick as Obstacle Sensor Module as shown here in the Letter Box i.e Just 2-3 below the Window inside the Box. And mount the LED Module on the Top of Letter Box, for indication.
Provide the +5 volt and Ground to an Obstacle sensor Module from Arduino Board. No need to connect any thing in Enable Pin of the Module. And connect the output pin to the Digital Pin 2 of Arduino Board.
Connect the +5 volt & Ground of LED Module from an Arduino Board. And connect the B (For Blue Light) to the Digital Pin 10 of Arduino Board.
Step 3: Reset Using Remote Control
Select Any Pin on SIRC Remote Control. Note the readings of that button by loading the code of SIRC Remote Control of my previous Instructable. According do the Changes in the Program of the Letter Box. Finally that Key will be used for Resetting.
Reset is required to switch off the LED when you take your Letters out of the Box.
Step 4: Code
Code here will initialize one Counter and will increment it once an Obstacle is being Detected by Sensor (i.e A Letter). And whenever the counter is greater than zero the LED will be set High & thus we will get an indication that a letter was Arrived.