Week 9

Output Devices

Pictures

Making Sound

Storaging Premade Sound

SSD to ESP32 MP3 Player Module

Generating Sound

I2S DAC w/ Amplifier
  • I2S Protocol for Audio Data
  • 3 different time sampling rates
  • sounds that respond to what you are doing not as precorded ones but generated in real-time with sin wave frequencies (final project idea: what if i could control the sound with drinking water?)
  • Send out the audio samples along the sin waves. But there is PWM involved. Each note is a waveform. Then each note is modulated by the PWM signal. Why add the PWM in the first place? It allows for more control over the sound output and can help reduce noise.
  • Making sound at the lowest level
  • can not vary the resistance continuously because the power transistor does not want to be in between open and close for a long time. PWM controls how fast we are toggling the switch to produce the waveform.
I2S Protocol is like I2C but for audio data.

Generating Movement

  • Servos
  • Stepper Motors
  • Linear Actuators
  • Brushless Motors. Amps and dollars scale 1:1, 1000 AMPS = 1000 dollars like a car application.

Insert Header

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Notes from Class

MOSFET. Two things to know, RDF and RDS on. RDF is the resistance from drain to source when the MOSFET is off. RDS on is the resistance from drain to source when the MOSFET is on. You want a low RDS on so that when the MOSFET is on it does not waste power and heat up. At low VGS, the MOSFET is off and the current is blocked, bad inductor. At high VGS, the MOSFET is on and current flows, good inductor.

Don't need a current limiting resistor if you have enough resistance in the circuit. The gate of the MOSFET is capacitive so it draws a lot of current when switching. If you have a low resistance circuit, the current spike can damage the microcontroller pin. A resistor in series with the gate limits this current spike.

So enough diodes in series can act like this big resistor, limiting the current spike when switching the MOSFET.

Heat transfer matters when LED brightness is high cuz they can get hot quickly. Make sure to use a heat sink or other cooling methods to keep the temperature down.

MOSFET half way between on and off is bad cuz it dissipates a lot of power as heat, very resistive. When it switches it is "noisy".