Results
Our oscilloscope works well within a good accuracy. In general,
on the x-axis our results are as good as our choice for our timer1 compare match value,
which we chose rather carefully. The y-axis is divided into 200 mv, which gives us
results within 100mv of the correct value. This is because if the result is in between a
200mv value, if it is 100mv, it goes to the next highest 200mv level, and it is under 100mv, it
goes to the closest lower level. In terms of our time/division findings, we worked
with a range between .1 sec/division to 2ms/division because, at best, the lowest we
could go was 2 ms/division. This was due to the fact that during our ADC conversion we
need 13 cycles to complete it. Hence, we needed to take this time into account, so that
all the samples could be retrieved during the conversion. To be sure, of course, we
double-checked our results with our findings on the computer scope card. For instance, for
the same sine wave, we measured our Vpp to be about 2.69 volts, and the scope measured
2.72 volts for its Vpp, approximately a 1.1% error. A more illustrative look is
presented below for your convenience.
Here is a sine wave on the Scope Card: Note Vpp of 1.9 Volts and wavelength of 10ms. And Below is the same sine wave on our Scope with Vpp 1.828 and wavelength of 10ms
Above is a sine wave of 250 ms wavelength and Vpp of 1.9V. And below is the same wave on our scope with 250 ms wavelength and 1.826 Vpp.
In terms of procedures and methods we would do differently, we
would definitely
try to implement the LCD screen that we had originally intended to display the
waveform. Due to time constraints and problems addressing the screen, of course, we
decided on using HyperTerminal. Also, we would have tried adding some more
features. For instance, we would have like to have determined the frequency of the
wave. This was extremely difficult to implement , and we felt that we had done our scope
justice considering where we started, with an LCD screen that displayed garbage,
and ending with a hyper term window displaying an almost exact replica of a waveform
shown on the computer scope card. This project was truly challenging, yet it was also
very rewarding feeling when you see the product you created does indeed work!
.