Piezo Speaker

Description

A Piezo-Speaker has two connectors and can generate sounds if you apply a frequency. One is + and one is -. If you connect it to the ESP + is connected to the Pin and - to GND. With the speaker in the LMUBox the long Pin is +.

How to connect it electrically

How to control it in MicroPython

Basic code to generate a 500 Hz signal

 1 from machine import Pin
 2 from time import sleep, sleep_us, sleep_ms 
 3 
 4 # assume our LED is connected to Pin 26, we use it as output 
 5 myLED = Pin(27, Pin.OUT)
 6 
 7 #generate a 500Hz on/off signal
 8 while True:
 9       # this switcheson for 1ms = 1000 us
10       myLED.on()
11       sleep_us(1000)
12       # this switches off for 1 ms = 1000 us
13       myLED.off()
14       sleep_us(1000)

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.

 1 # beeper code from https://micropython-on-esp8266-workshop.readthedocs.io/en/latest/basics.html#beepers
 2 from machine import Pin, PWM
 3 from time import sleep
 4 
 5 tempo = 4
 6 #notes and corresponding frequency
 7 tones = {
 8     'c': 262,
 9     'd': 294,
10     'e': 330,
11     'f': 349,
12     'g': 392,
13     'a': 440,
14     'b': 494,
15     'C': 523,
16     ' ': 0,
17 }
18 pin = Pin(27, Pin.OUT)
19 # Init Beeper without frequency.
20 beeper = PWM(pin, duty=512)
21 melody = 'cdefggaaaagaaaagffffeeddddc'
22 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]
23 
24 for tone, length in zip(melody, rhythm):
25     beeper.freq(tones[tone])
26     sleep(tempo/length)
27     
28 beeper.deinit()