From Thursday through the long weekend...

We met everyday from Thursday through Monday (yes, even President's day) to continue development of our project. Our mission was to continue working upon our code of making a LED light blink, but instead of having it already programmed into the pic, we wanted to use the USB interface to control the blinking. Ideally, we wanted to have a system working such that if we plugged in the USB cable attached to our bread board (on which the Pic is connected), the connected PC would detect the "new hardware" that we had just connected, and then would allow us to use some sort of GUI to control the LED.

To prepare for this, extensive reading was done. We also turned an MC1455 into a 20MHz oscillator. However, though the resistor and capacitor values we used to achieve this seems to be correct, after using an oscilloscope, we found that it was only running at 2MHz. We are unsure whether this was an error in the oscilloscope, or in the equation we used to try and create the oscillator. Now, we have created a 4MHz oscillator to act as our external oscillator, and further testing will see if we need to change this as well. We have an old satellite receiver, on which has three crystal oscillators, but we are unsure of whether they work or not. Nevertheless, we have managed to de-solder one of them, and will test it on the oscilloscope to test its actual frequency rate. In the worst case, we will go out to Action Electronics and purchase an oscillator from them.

Slow steady progress

After our last couple of meetings, we have managed to correctly create a program to make an LED blink using our pic. This is important because it has accomplished three tasks. First, it has proven to us that the pic actually does work, and that we are able to program it and change the program at will. Second, being able to output voltage through the pins of the pic is extremely similar to what our pic will be doing in its final stage -- the only difference being that it will have to output at a certain time instead of turning on and off at a regular interval. Lastly, thanks to this experiment we were able to finalize the language of choice to use for the pic's program: C (as opposed to Assembly).

We are now trying to create an interface between a USB port and the pic itself. We have done a good amount of research on it, and are beginning to use some sample code online and integrate it with our pic. Our next goal is to use the USB interface to allow a computer to dictate when the LED will light up. If we can accomplish this little task, then we will be able to fully connect our image processing program with the pic.

Things are slowly coming together

Our new pics have arrived. These re-programmable pics are compatible with the pic programmer, and testing of it will begin shortly. We have successfully mounted a stepper motor on top of another stepper motor, and tested to see if the stepper motor on bottom can still rotate with the added load. This test proved successful, and the entire contraption will be complete soon. All four stepper motor drivers have been soldered onto a circuit board, and because we are able to hook up one successfully to a stepper motor, we can just duplicate its setup for the other stepper motor drivers. Things are really coming together, and completion of the initial prototype is imminent.

Technical Difficulties

We have finished construction of the two stands for the stepper motors/spotlights. We plan to add bridges to it to increase the stability of the structure. The height of the stands have been overestimated so that if need be, we could cut off some of its height to better fit our project. There may be some difficulties connecting the stepper motors to the bred boards (as the stepper motors are now mounted so high above the ground), but this could easily be remedied by soldering additional wires as intermediaries between the two.

We also tried to use our new threading set to thread the shaft of the stepper motor, but this proved difficult because it is difficult to keep the stepper motor's shaft from rotating while simultaneously threading it. We plan to use some sort of tool to keep the shaft steady the next time we meet.

Construction of the stage

We turned our attention to another part of our project that needs to be completed before the Senior Design Expo: the stage. Initially, we were planning on using a regular table to act as our stage, but because of potential errors and complications that could occur from using one of the provided tables (perhaps light would refract of the table, or it was unsteady...the potential list of problems goes on) we decided to create a stage on which to mount all our necessary equipment on (the stepper motors, stepper, spotlight, camera, etc).

We bought the necessary materials which included plywood, aluminum, screws, and begun working! The basic layout is to create a plywood matting on which we could place on top of any tabletop. On this matting would be a clearly marked of area to act as our stage, while having some leftover space on the matting to erect several stands that will hold the stepper motors and the webcam. The stands will be constructed to a specific height so we can use that height in the calculations we need to make (when finding the person on stage).

Yet another task that we will work on simultaneously with the list of other things we have to do.

Pic Programmer

On Tuesday, we were able to acquire our pic programmer, which we hastily began to work on. Using our own laptop with the necessary software (MPLAB IDE), we immediately took some simple code (to test the functionality of both the programmer as well as our pic) that would light up a LED light, and attempted to test it. But after hooking up the pic to the LED, we were baffled to find that the LED did NOT light up. Initially, we assumed that our code was incorrectly programmed, and proceeded to debug it. But after we found no error, we assumed that we were not using the software correctly. It was only after we brought up our problems with Professor Ihler was the REAL problem found. We had bought a OTP pic: One Time Programmable. Naturally, we did not do this intentionally. But we had overlooked this one piece of valuable information. Good thing we had bought two spares of the same pic.

We now have two paths we can choose to take. We could go ahead and order another pic (this time a RE-programmable one) and work off of that, OR to save money, we could thoroughly test our program on the software simulator, THEN attempt to program on our remaining pics. This approach is extremely risky (as we only have two tries before we are out of options) but is a road we are still contemplating as we have already passed our set budget.

Using the new lab

Today we decided to test how the stepper motor works when given a step function. So, we have gone to the lab today to use the Arbitrary Waveform generator. And after spending a couple of hours to learn how to use the machine properly, we are able to make the stepper motor move with various step sizes, step speeds, making it start and stop, etc. The results of these experiments will be useful when programming our pic, which we will be the goal of our next meeting provided we are able to acquire a pic programmer. A video of our results will be posted shortly.

Also as an update to our project, we have decided to use a laptop instead of the NSLU. And should we have time after completing the project, we will go back to it. This will allow us to advance in our project without further hindrances.