Week 5 - Making Prototype Code, Sharp Rangefinder Not So Sharp Any More

Sharp GP2Y0A21YK0F

Sharp GP2Y0A21YK0F installed into the case lid

During development of the prototype code we hit several roadblocks. The first of which being that the Sharp 2Y0A02 rangefinder module died during testing of one of the revisions of the software prototype. This was particularly difficult to diagnose because it did not go suddenly, but rather it gradually deteriorated over the course of a few hours to the point that the readings were no longer readable. Fortunately Fabio was able to source a new rangefinder from Amazon, the Sharp GP2Y0A21YK0F, and order it with expedited delivery so that it was delivered within the week. We had originally ordered a second Sharp 2Y0A02 rangefinder but the supplier informed us that they were out of stock and on short notice the Sharp GP2Y0A21YK0F was the only one we could get a hold of. The Sharp GP2Y0A21YK0F had a more limited range, making it less ideal for the project than the Sharp 2Y0A02, but still worked to give some reading at least and allowed Liam to continue developing the code. The new rangefinder also needed to be modified as the old one had been to mount more easily to the front of the case. Fabio performed the modification differently this time however as it was suspected that the modification may have been the cause of failure for the dead rangefinder. This time he simply swapped the cable plug from the front side of the sensor to the backside, rather than removing it altogether and replacing it with wires as had been done with the previous one, which had actually caused some of the PCB to peel from the strain.

The second roadblock we encountered was when the accelerometer and gyroscope module suddenly stopped working during development. After a couple of hours of debugging and testing however this issue was tracked down by Fabio to be caused by a poor solder join on the VCC pin. After Fabio re-soldered the join Liam was able to continue development.

Liam also encountered some code-related issues whilst developing the code. The accelerometer and gyro module would read as being rotated to a roughly 90 degree angle when the device was held as intended. This was due to the fact that the way the module was mounted inside of the case was not being compensated for. This was solved by using the first reading from the module as an offset for all subsequent readings.


By the end of the week the code prototype was finished:
https://drive.google.com/file/d/0B5ZXvoDnC39FR1VnenNDbF95b2s/view?usp=sharing