Goal | Class Archive | Video | Challenges | Related Classes | Class Notes | Review Materials | Assignment
Goal
add an output device to a microcontroller board you’ve designed and program it to do something
Video
Challenges
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Class Notes
Output Devices
Electrical Safety
Power electronics = more voltage and more current
As current and voltage go up, we need to be more careful similar to dealing with machine tools.
Power electronics deal with larger capacitors whihc store charges for longer times.
Convention: In the examples this week, unpolarized connectors are used. Unpolarized headers used for convenience, the header points in with the ground on the right. If you have a voltage regulator (I 6-30V / O 5V) and connect it backwards, you will fry the regulator. Connect a diode to protect from connectiong regulator backwards.
Power Supplies
You pay more for more power and how quiet it is. Do not use batteries for these examples.
LED Array
Charlieplexing
Additive process – cast epoxy film can be soldered, copper tape added to simplify design with same code
LCD
LCDs universally use HD44780U
Video
Simple, output should be generated very quickly.
A little thing can produce a lot of information on a big screen by synthesizing video. Nice example of speed and power of processors.
Speaker
MOSFET let you source or sync a lot of current.
Need to pulse width modulate acoustically. The Hardware counter knows how to PWM. For higher fidelity, use class D amplifiers.
DC Motor
H-bridge, for the motor (or better audio) current goes in either direction. By turning transistor on in pairs, you control directions.
Trace width calculation
As you start ot use more current, the resistance of the traces matter. If you use skinny traces with a lot of current, you start to dissipate power in them and they heat up. Trace width calculators are available.
DC Motors want to spin very fast to be efficient.
Servo motors
Instead of spinning continuously, direction is adjusted.
Review Materials
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Assignment
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