Editing PAM8403 Stereo Amplifier

= Description =
An amplifier can be used to driver bigger speakers and to generate sound that is louder. 

The amplifier is connected (similar to a [[speaker]]) to the ESP32/ESP8266, it is also connected to power, and then it has connections for the speakers.

[[File:File:Amplifier.PNG|x200px]]
[[File:Amplifier2.PNG|x200px]]
[[File:File:Amplifer03.PNG|x200px]]

= How to connect it electrically =
[[File:Piezzo.PNG|300px]]

= How to control it in MicroPython =

== Basic code to generate a 500 Hz signal ==
<syntaxhighlight lang="python" line='line'>
from machine import Pin
from time import sleep, sleep_us, sleep_ms 

# assume our LED is connected to Pin 26, we use it as output 
myLED = Pin(27, Pin.OUT)

#generate a 500Hz on/off signal
while True:
      # this switcheson for 1ms = 1000 us
      myLED.on()
      sleep_us(1000)
      # this switches off for 1 ms = 1000 us
      myLED.off()
      sleep_us(1000)
</syntaxhighlight>

== Code to play a melody - decoding notes ==
Example code shows how you can play a melody with the speaker. If you want to add higher notes see https://en.wikipedia.org/wiki/Piano_key_frequencies for the needed frequency. The example code was taken and edited from https://micropython-on-esp8266-workshop.readthedocs.io/en/latest/basics.html#beepers.

There are some issues with restarting PWM outputs - see [[Known Issues]].

<syntaxhighlight lang="python" line='line'>
# beeper code from https://micropython-on-esp8266-workshop.readthedocs.io/en/latest/basics.html#beepers
from machine import Pin, PWM
from time import sleep

tempo = 4
#notes and corresponding frequency
tones = {
    'c': 262,
    'd': 294,
    'e': 330,
    'f': 349,
    'g': 392,
    'a': 440,
    'b': 494,
    'C': 523,
    ' ': 0,
}
pin = Pin(27, Pin.OUT)
# Init Beeper without frequency.
beeper = PWM(pin, duty=512)
melody = 'cdefggaaaagaaaagffffeeddddc'
rhythm = [8, 8, 8, 8, 4, 4, 8, 8, 8, 8, 4, 8, 8, 8, 8, 4, 8, 8, 8, 8, 4, 4, 8, 8, 8, 8, 4]

for tone, length in zip(melody, rhythm):
    beeper.freq(tones[tone])
    sleep(tempo/length)
    
beeper.deinit()
</syntaxhighlight>

[[file:Piezo_Speaker.jpg|300px]]
[[file:Piezo_Speaker_close_up.jpg|300px]]

= Related Tutorial Videos =
<youtube>HPQMvL1SP_c</youtube>