Day 9: (Wed Sep 29, Week 5) Photointerrupter in Action¶
Notes for 2021-09-29.
New Assignments¶
New assignment, due next class: Exercise: Reactive Marble Run Tile.
Agenda¶
Summary electrical theory review.
Introduce new assignment.
Demo of reading a switch with a Pico.
3.3V vs 5V circuits
Oscilloscope demo.
Sample code walkthrough: digitalio, logic levels, state machines, hysteresis.
Sample CAD walkthrough.
Sensor lead extension and heatshrink demo.
Hand out a few more parts from the F21 Course Kit (1931, 6049, 482).
In-class sketching, prototyping, and individual design review.
Supplementary Video¶
Electrical Theory Introduction: https://youtu.be/d5HxmQHCO48
Kirchhoff’s Laws, Ohm’s Law: https://youtu.be/hnbD_D4ljOE
Resistors and Voltage Dividers: https://youtu.be/j8rvBSPiiUI
Switch and LED Circuits: https://youtu.be/lY3ckgUBEbg
Reflective Photointerruptor: https://youtu.be/atuFgbVYVsA
Resistive Circuits in Tinkercad: https://www.youtube.com/watch?v=mX5L67WcWec
Photointerrupter Circuit¶
![../_images/LTH-1550-circuit-sketch.png](../_images/LTH-1550-circuit-sketch.png)
A photointerrupter circuit includes a current-limiting resistor for the LED and a bias resistor for the phototransistor.¶
![../_images/Pico-R3-SDK11-Pinout.png](../_images/Pico-R3-SDK11-Pinout.png)
Raspberry Pi Pico diagram of pin functions.¶
Essential Lab Equipment¶
![../_images/breadboard-connections.jpg](../_images/breadboard-connections.jpg)
Solderless breadboards are our workhorse for electronics prototyping. Each short row of five holes connects together by an internal metal clip and forms a single circuit node. Each long bus row is a node. Please disregard the +/- bus labels on your breadboards.¶
![../_images/CSI550S-Lab-Supply.jpg](../_images/CSI550S-Lab-Supply.jpg)
Three-channel lab power supplies.¶
![../_images/Extech-EX330-multimeter.jpg](../_images/Extech-EX330-multimeter.jpg)
Digital multi-meter (DMM).¶
![../_images/DS1102E-oscilloscope.jpg](../_images/DS1102E-oscilloscope.jpg)
Digital oscilloscope. For more details, please see Oscilloscope Guide.¶