Update 2

Welcome back!

Sorry I have not updated in a while, I’ve been busy with the project. Right now I have completed getting the computer to communicate with the arduino and a GPRS shield.

I ran into some problems over the past few weeks. First, the documentation on what will and will not work as a power supply for the GPRS shield were quite vague… different documents had different specifications, and I needed to make sure that the power supply I was using would work for sending SMS (text messages). I had found that the shield can be powered by the Arduino itself. Some documentation says that the GPRS shield may pull too much current, but I have not run into a problem, yet. I do have replacement Arduinos in case something goes wrong, but I don’t see that being a problem.

This leads me to another problem I ran into. The SeeedStudio GPRS shield does not work with an Arduino Uno. This was one of my biggest problems because I was hoping to try to use the UNO (my own personal board) for some testing (in case it did fry the board, I would fry my board rather than the research group’s board, an Arduino Duemilanove). I am not sure why it does not work with the UNO. I can get it to start to communicate, but once I start to give it any commands,  it says there are errors. I will be looking into possible solutions in the upcoming weeks(I believe that I heard somewhere that the Duemilanove is being discontinued).

I had to find a SIM card to work with the shield. I found an inexpensive ‘pay as you go’ with unlimited texting from AT&T which seems to work.  A problem I ran into was that I could receive texts, but I couldn’t send them, and I couldn’t see if I was actually transmitting anything. I was debugging and thought of two possible problems: 1) insufficient power. And 2) I was trying to send to the wrong number. After hours and hours of tampering, I found some commands that mentioned an SMS message center number. I was able to set the number into the shield, but that is something that will need to be changed when the machines are placed in Ghana.

Goals for the following week:

·     *           Get the arduino/shield to text as a ‘stand alone’ system (without needing a computer)

·     *           Find a battery to use…  with correct voltage and current, rechargeable, and can be adapted to connect to the arduino.

·      *        Combine the arduino and vending machine so have a working prototype.

·      *        Start documentation on assembly.

Other goals:

·      *       Put together a flash drive with all necessary programs and files to edit and download software on site.

·        *       Assemble wiring for easy assembly on site.