Week #11: (11/16-20) End of Semester Project, Chapters 6-8.

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Week #11: (11/16-20) End of Semester Project, Chapters 6-8.

Post by rjagodowski »

I have also posted the information about the End of Year Project here. A printed copy will be given to you in lab the week of class on 11/16/20.


We'll begin this week with a discussion of the End-of-Semester Project. Details are posted here.

For the next couple of weeks we will discuss key topics from Chapters 6 through 9 in the text.

These key topics are:

Light (Wavelength & Color) and the Phototransistor (Page 171)
Basic Stamp I/O Voltage Levels (Page 176)
Ohm's Law (Page 177) and Phototransistor I/O (Page 178)
Capacitors (Page 180) - Reading Capacitor Value: 0.1 uF = 104 (Page 181)
QT (Charge Transfer) circuit for Phototransistor Light Sensitivity

Completed to this point on 11/20/20. Next class (12/4) we'll pick up with the RCTIME Command.

RCTIME Command (Page 184) and on page 363 in Syntax & Reference Manual (P6 used as output AND input)
Fig. 6-13 on Page 188 showing voltages RC Voltage decays due to charge transfer and light intensity.
PWM Command on Page 191 in Boebot text and Page 355 in the Syntax & Reference Manual.

PWM from Sparkfun.com

OK....this is beyond the scope of this course (I discuss it in the senior course EET-200 Solid State Devices), but scroll down to the video near the end of the page on This Link from CircuitDigest.com to show a DC motor being controlled by a PWM signal. In this case the PWM signal is being generated by an integrated circuit known as a 555 and MOSFET transistors using in an H-Bridge configuration are used for the current switching needed for the motor. If you look at the oscilloscope screen in the background, you will see that the wider pulses result in higher motor speed and the thinner pulses result in slow speed. Note that even with the skinny pulses, the motor is still receiving the FULL VOLTAGE so that the motor can develop its maximum torque (spinning force), just for a shorter period of time. The meter in the background is displaying the supply voltage (12V) and the current drawn. Notice the current increases with increasing motor speed, as would be expected. The manual switch reverses direction.

Normalizing ambient light values for navigation on Page 194 in Boebot text, calculations on page 200.
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