The first accomplishment of the environmental sensing module was the design. Upon first hearing the idea, we quickly came up with the general concept. The next accomplishment was just getting the parts, ordering delays and shipping problems had us wasting large amounts of time waiting on parts. Miscommunication also played a part in slowing us down. When ordering sensors one team member was under the impression that the Altera DE2 board had an analog to digital converter, it does not. So ordering analog sensors and sending them back took a decent amount of time as well. Our third accomplishment would be the system build. Every time the environmental sensing module starts up it puts a smile on our faces, especially because it had to be built twice due to a malfunctioning computer. Our fourth accomplishment was switching from assembly language to C with only a few days left to work on the project. The fact that we even got it measuring is a miracle at this pace. Our final accomplishment will be to finish up all the accompanying paperwork, like I said, we just started getting data.
ADXL345. That is our uncertainty, our system sees the accelerometer. The accelerometer is transmitting data; the problem is it is wrong data. If we had a few more weeks, we could order another ADXL345 and I imagine it would integrate and work immediately. Unfortunately we do not have this extra time. We spent a few weeks attempting to get the ADXL345 to work with no success in assembly language. When we switch over to C, we still could not get good reading. So as time was coming to a close, we focused on the SHT21 and the real time clock. Both of these ICs integrated into the system without problem and interfaced using the I2C protocol. Now as a group we were really confused, because the ADXL345 uses the same protocol. A protocol we have already proven effective. So on our last possible day to work on our project, we decided to run a self test on the ADXL345. The figures below shows a range of values we expected to get and the range of values we did get, as you can see the ADXL345 is not working. When the IC got damaged and stopped working is a mystery to us, unfortunately they do not come with a tiny environmental sensing module inside of the ADXL345.
Two of our sensors, the real time clock and the temperature/humidity sensors both communicated with the Altera DE2 board as expected. Even the sensor that was outputting faulty information still was able to communicate with the DE2 board. Obviously this means the scope of the project has been proven successfully. Had we a working ADXL345 I have no doubts that the environmental sensing module would have accurately recorded temperature, humidity, and shock without fail. So the lesson we shall take away from this project is to run the self-test first on all ICs. Even with this set back, I believe that the data shown below should be enough to call this project a success.