Update to “Dumbwaiter Challenge”

If you’re reading this you should already be familiar with the previous build, if not you can find that post here.

The previous post solved was a great proof of concept and was pragmatic and functional. This update adds a bit of flair and builds on the previous ideas. Basically we are doing what several other electronic devices have done over the years, we are going wireless! Thats right! Using Xbee modules the arduinos can use the same serial communication it did in the previous project and the Xbee shield has space to mount all the hardware we had to use breadboards.

Here is a list of the parts you will need:

(2) Arduino uno
(2) Xbee
(2) Xbee shields
(1) red LED
(1) yellow LED
(1) green LED
(1) 270Ω resistor 1/4 watt
(2) ultra sonic distance sensors
(10) female pin header
Hookup Wire / Jumpers  cables

Some tools you will need:

-Soldering set up
-Iron
-Solder
-Sponge
-Helping Hands
-Drill
-Bit with diameter of sensor heads (about 1 inch)
-Ruler to measure placement of holes in the dumbwaiter

The schematic is similar to the last one but there are a few changes

 photo Screen Shot 2015-04-29 at 12.35.15 AM.png
The Arduino on the left is the Arduino Rx and the Arduino Tx is on the right

Preparing Xbee shield Tx

Now its time to start the upgrade!

This time we will begin by working on the Xbee Shield’s empty space. Grab a Xbee Shield and we will solder a female header right next to the 5V pin. You can lineup the labeled Arduino in case your Xbee shield isn’t labeled

 photo IMG_3798.jpg
This image shows the XBee shield with the female pin header in place. The cast shadows covers the 5V pin label. photo IMG_3799.jpg This image shows the underside where the actual soldering takes place. (masking tape is very effective at holding components in place while flipping them over to solder)
Next we need to connect the pin header to the 5V pin, I used a stripped piece of hookup wire and soldered it to 5V pin and the female pin header

 photo IMG_3800.jpg
This Image shows the connection between the 5V pin and the female pin header before soldering
 photo IMG_3801.jpg
THIs image shows the 5V pin soldered to the Female pin header
This XBee shield is ready to be installed on the Arduino Tx, the one with the Ultra sonic distance sensors. The hook up is identical to the last post. simply connect the ground to ground pins and now the board has 2 5V pins eliminating the need for the bread board. And the Signal pins are connected to pin 12 or 13

Preparing Xbee shield Rx

Now we move on to the other XBee shield, this one needs a little more work, have the Pin headers and the resistor on hand. Instal the resistor and female pin headers as shown.(don’t snip the resistors legs!!) photo IMG_3812.jpg

Solder like so
The resistor protects the LEDs and the female pin headers make swapping of LEDs very easy.
 photo IMG_3810.jpg
Now this Shield is also ready to be installed on to the Arduino. The hook up is simple place the LEDs on the female pin headers that are spaced apart with the cathode(negative/flat side) on the side of the resistor. then use jumpers wires to connect them to pin 7,6 and 5. Before you test the project be sure to read the notes section for some important information.

It Works!


Some Notes/ Troubleshooting

-The Xbees act like a wireless version of serial communication therefor there is a Tx and Rx and they need to be set properly or the Xbees wont communicate. Reference the Images Provided
-If you attempt to power both arduinos with 9V batteries the transmitting Arduino will not transmit any data, you must use an external power source or 4 AA batteries.
-The code used in each Arduino is exactly the same but here it is again Arduino Tx  Arduino Rx
If you try to upload the code with the Xbee shield in place the Arduino IDE will not allow it and give you error codes, simply remove the shield when uploading the code and reinstall it when done uploading the code.

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Dumbwaiter Challenge

Hello George,

We are writing in response to your letter describing a series of problems in your hotel. We have discussed it and we have found we can best help you with your problems with the dumbwaiter your patrons have been over filling.  We have devised a way for you to be notified of the status of the dumbwaiter. There will be sensors in the dumbwaiter that will measure the distance from the top of the dumbwaiter to the height of the stacked dishes. Those measurements will be interpreted and will light either a red, yellow, or green led. The red will mean the dumb waiter is overfilled and requires your assistance before it can be operated. Yellow will mean it may possible to operate but as it will be moving, things might shift and could possibly get jammed. Finally, green will mean the dumbwaiter is within the normal filling range and can be operated without worry. In order to have this feedback system working you will need to install sensors in the dumbwaiter and program an Arduino. We will walk you through the steps and will even help you understand how the system works. These instructions will give you a working prototype. We understand that you are busy and might not have the time to go through some of the set up required, so we also are working on a upgrade that would make the system wireless thus simplifying the set up and making the capacity indicator portable.

Here is a list of the parts you will need:

(2) Arduino uno
(1) red LED
(1) yellow LED
(1) green LED
(2) ultra sonic distance sensors
(1) breadboard
Hookup Wire / Jumpers  cables photo 249769E9-9E5B-4606-BEF4-AA77D06C8FB3.jpg


Here also is a more formal Bill of Materials (BOM).

 photo Screen Shot 2015-04-27 at 1.53.54 PM.png


Before we get started on the actual build you should familiarize yourself with the schematic for the build and what system will look like once completed, shown here.

 photo IMG_3776.jpg
The wiring may look confusing but it will all be made clear in the project schematic shown below.

 photo Screen Shot 2015-04-27 at 1.03.26 PM.png


Preparing Arduino Tx

Now that you’re familiar with the schematic, its time to build! It’s quite simple, it’s just a matter of connecting the components to the right pins on the Arduino. Fortunately we already wrote the code for you so you just need to follow our instructions and you will have a working prototype in a few minutes.

1.  First gather your 2 distance sensors and one Arduino, we will call it “Arduino Tx”. The sensors will have 4 pins you can go ahead and wrap a bit of hookup wire connecting the 2 middle pins(Trig and Echo), we will call this junction the signal pin. The other two are labeled Vcc and GND thats Voltage and ground respectively.

2.   We will begin by connecting the sensors to the Arduino Tx. Next connect the signal pin into pin 13, then Vcc to the 5v pin on the Arduino. On the second sensor, connect the ground pin to the ground pins on the Arduino, next connect the signal pin or trigger and echo into pin 12, then Vcc to the 5v pin on the Arduino. Because the Arduino only has one 5V pin use a breadboard to connect the two pins with the 5V pin like shown.
 photo b2fa5c95-2bb7-43cc-9ce2-cbb1b849ad82.jpg

3.  Now upload the code to the Arduino 1. It is now ready to send the distance information to the Arduino 2.
Here’s a link to the code.
 photo Screen Shot 2015-04-27 at 11.50.26 AM.png 

4.  On the other Arduino (Arduino Rx) we will set up the LEDs. Using a bread board connect the green LED’s anode to pin 7 and the cathode to the ground pin. Next connect the yellow LED’s anode to pin 6 and the cathode to the ground pin. Next connect the red LED’s anode to pin 5 and the cathode to the ground pin.
 photo da5c55eb-bded-471e-abd5-a7ec1bbf6117.jpg

5.  Now upload the code to the Arduino 2. It is now ready to receive the distance information to the Arduino 1
Here is a link to the code

 photo Screen Shot 2015-04-27 at 11.51.24 AM.png  

6.  Now wire for serial communication by connecting a wire from Arduino Tx pin 1 to Arduino Rx pin 0, and another wire from Arduino Tx ground pin to Arduino Rx ground pin.
 photo IMG_3775.jpg

7. Both Arduinos are ready. Simply power both Arduinos and the system will be functional!
On the transmitting Arduino(Arduino 1/Arduino Tx) its best to use 4 AA Batteries
The Receiving (Arduino 2/Arduino Rx) will work just fine with a standard 9V battery

8. One last thing we tested and designed this system by strategically placing the sensors on top of the roof panel of the dumbwaiter you described. If you want to change the placement to better suit your dumbwaiter the system will still work. we placed them evenly across the image shows the holes for the sensors from above. photo 7685B7D4-1DD8-4301-A1F3-AB4F1C8B0712.jpg

And there you have it, your fully functioning “Smart Waiter.” To improve this project even further you could set up multiple Xbee receivers i.e. one that you could carry around with you to let you know when the waiter is full or getting there. Another improvement would be to add more steps of “fullness” with some added code and more LEDs hooked up to the receivers. Last but not least, you could add an alarm or buzzer of sorts to not only give a visual warning, but an audible one to heighten awareness of the urgent and desperately dire issue that is the overfilled dumbwaiters. If your interested in making it wireless follow this link Thanks for reading.

Electronics Final Guidelines

1. description of problem (cover letter)

2. How you are solving from the point of view of george & his patrons experience
3. in order to make that happen…
4. this is what you’ll need
–tools/ bill of materials
–pictures
–establishing, people using
–establishing, inside guts
   -(block diagram)
–schematic(step 3 or 4)
5. Step by step instructions
(code at the end)
6. closing thoughts
   -what he might try to do differently
   -minor problems he might run into not in the step by step