Piezo Speaker
Revision as of 14:41, 29 August 2020 by Skwhadmin (talk | contribs) (→Basic code to generate a 500 Hz signal)
Contents
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 speaker is connected to Pin 27, 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()
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