Team Glen – Prototype I Final Report: Smart Mailbox


The Smart Mailbox project is designed to target a wide range of consumers from people living in remote areas to people with disability.  The Smart Mailbox is mainly designed to help people with mobility issues that find it a chore to check their mailbox everyday just to see if they have any mail or not.  This is especially true if the weather is bad, if they are having any health issues or just want to know if there is mail to be picked up.  The project our group is currently working on will address some of these issues.  Our Smart Mailbox System uses infrared sensors to detect mail and wirelessly transmits a signal to the receiver unit that is located inside the owner’s house.  The notification from receiver unit will alert the owner that mail has just been delivered to their mailbox

The materials we used for this project are:

  1. Two Arduino microprocessors
  2. Two Xbee Pros
  3. Two Xbee Shields
  4. One Infrared LED
  5. Two Infrared Transistors (IR sensors)
  6. One 1K ohm resistor
  7. One 330 ohm resistor
  8. Two 500K ohm resistors
  9. Two LED’s
  10. Wood used to create insert
  11. Hookup wire


The Arduino first provides power to the infrared LED which you will not be able to see it on unless you are viewing it through some device like a digital camera.  The infrared light is pickup by the two infrared transistor sensors on the sides of the insert for mailbox.  The infrared light will saturate the base of the transistor that will bring Vce=0 and thus grounding Sensor 1 and Sensor 2 Pins for a LOW digital state, as shown in the wiring diagram.  This is our “no mail state.”  The no mail state will not change until mail is place inside the mailbox which will trigger the “mail state.”  You only need to block the infrared light to one Sensor (Sensor1 or Sensor2).  When this happens, the resistance between the transistor’s collector and emitter goes to infinity.  This means that Vce=5v and Sensor1 or Sensor2 goes to a HIGH digital state.  This is our “mail state.”  These digital states are transmitted through Xbee to an receiving Xbee that is located some distance from the mailbox.  This will alert the owner that mail has arrived in there mailbox.  View the wiring diagram and Arduino Code below:                                                                                        

Below on the left is the mailbox with on the far left the transmitter Xbee Pro and Arduino board. Next to it is the receiving Xbee pro mounted on it arduino board.

LED on either transmitter and receiver are off with no mail in the box.



 Below on the right are both LEDs of the transmitter and the receiver turned out after mail have been dropped into the box.

As you can see the receive which is the assembly powered by a 9volt battery will be placed into the owner’s room.



Below on the left is a wiring diagram for both the transmitter receiving Xbee Pros attached to separate arduino boards.

On the right is drawing of the mailbox insert with IR sensor and color coded wired that will be connected to the transmitting

ardiuno and Xbee. 

Arduino code for the transmitter can be found under the below link:

Arduino code for the receiver can be found under the below link:


Our objective for part 1 of this project was to build and insert for mailbox, that can detect and send notification to the mailbox owner through Xbee Pros. We have successfully accomplished that. This success boosted our confidence on moving on to the second phase of this project, which will consist on implementing an RFID system that will be used to unlock and lock the mailbox upon exhibiting a badge in front of the box.

Then nicely and swiftly, we shall start working on how to enhance the range our Xbee Pros can cover as far as transmission is concerned.  

 As a 4th and final phase of our project, we shall look into how to expand this project to multiple users. Meaning by that have one arduino and Xbee control up to 7 mailboxes and notify the different receiver each mailbox owner has in his/her room. For now our earlier approach of solution to that is multiplexing. But until then we’ll still be looking for other ways to expand this project.

The project was overall fun to work on with no problems that we could not deal with.  A few comments on the insert we made and why it was designed it that way.  We were hoping to have the sensors mounted straight up and down for easy alignment of the sensors but we soon realized this would not be possible if we were to use the current mailboxes used at CPRF, our main clients in mind for our project.  The link below is what the apartment style mailboxes look like:

This is the mailbox we design our insert for.  You can also see when the postmaster opens the mailbox with the master key the whole thing hinges forward and the opening on top is where the postmaster places the mail.  Because of this top opening we could not have a straight up and down sensor system we were hoping for, which made thing more difficult to get proper angle alignment with the two sensors to the IR LED.

March 16th, 2012 3:53 pm

Good Job everybody on getting prototype I completed way ahead of time.
Glen, the presentation went well and the residents liked it.
Most of the comment we received were “I like what I see” or “you guys did a great job”.
But the most important one came from Beth at the end when we were done presenting the Smart Mailbox to her and went over the RFID system we plan on implementing to open and close the mailbox door.
She simply said “I like this”.
One of the suggestion we actually received was to have a push button that will make the blink LED on the receiver time out maybe for 2 hours, just in case the box owner, doesn’t want to go pick up the mail right away. Then after that timeout period the LED can resume blinking until either the mail are picked up or the push button is pressed again.

March 19th, 2012 3:37 am

All , I just figured out the code to address the issue of pressing a push button in order to turn off the LED on the receiver for a predefined time ex: 30 minutes, 1 hour, 3 hours ….
After the timeout period expires normal LED activities will resume until mail are picked up from the box or the push button is pressed again.
Please see my new post “addressing CPRF resident concern” for more details.

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