Finishing up

We were able to get the stepper motor working a couple weeks before the Expo. However, we could not figure out a viable solution to integrate the prism. The placement of the prisms and the direction of light was extremely temperamental and hard to calibrate. Additionally, we did not have enough time to figure out the mechanics required to rotate the prisms with the stepper motor in order to get the desired light frequency. This is because the frequency gradient, when split by the prisms, was very slim, requiring extremely small and precise rotations.

We were able to come up with an alternate solution that is much cheaper and easier to manage. Using the refraction of light from a CD (yes, a Compact Disc), we successfully split the light into a wide enough frequency gradient to get results. Using this solution, we were also able to get more intense light that is easier for the photo detector to see.

The Design Expo was a great success. We received complements from industry critics and praise from school faculty.

On the right track

After about a month of trying to get an ADC to interface with an 8051 micro-controller, we finally decided to try a different one. We were able to get it working within a day's work.

Currently, we have the new ADC connected to the IR photodetector, with the 8051 passing values to a PC through an RS-232 connection. The PC then converts the values into a CVS file in which we can graph with Excel. We also have new parts that we need to integrate into the system, including a stepper motor with a controller and prisms we intend to use to split the frequencies from a single light source.

Our current working parts list is as follows:

Atmel 8051 Micro-Controller

MAX232 (serial interface chip)

ADC (analog to digital converter)

IR Photodetector

Our soon to be working parts list:

Stepper Motor Driver

Bipolar Stepper Motor

Transistors (4 PNP + 4 NPN)

Glass Prisms

Dead Butterfly

I killed our young AVR Butterfly while soldering more pins onto it. I don't see any shorts on my soldering job, so it could have died due to poor transportation conditions.

We now have to re-think the design. We will consider using a stand alone micro-controller to build our own custom circuit. The advantage is in avoiding the extra cost of buying a pre-packaged design. The butterfly has features that we will never use, and if one component goes bad, the whole thing is dead. Additionally, using separate components will allow for more flexibility incase our design requirements change.

Miscellaneous Project Notes

List of Parts

Amtel AVR Butterfly

Pin Headers, 0.1 inch

USB to RS232 (Serial) adapter

Some sort of IR emitting device

Some sort of IR detector

Useful Links

AVR Flasher for OS X	http://www.ipnas.org/garnir/avr
OS X driver for our PL2303 USB-Serial adapter	http://sourceforge.net/projects/osx-pl2303/