ESP8266 / ESP-01 NodeMCU playing the Imperial March

Looking at the NodeMCU documentation, I came across the PWM feature of the Firmware. And one of the fundamental laws of electronics is: "If it can make noise, it has to play the Imperial March."

Gooooogling didn't show any results, so it might not have been done before. We can fix that.

I found a rather nice Arduino sketch by Andre Tagliati here and ported that over to LUA for the ESP8266. So all the credits for the artistic work converting the original score go to Andre.

The schematic is rather simple:

I had found a piezo speaker in the junk box. That connects to GPIO2. I added a 100 Ohms resistor just because of a gut-feeling that at high frequencies the current might be too high. It works without that just as well.

The rest of the circuit is exactly the same as always.

Now for the interesting bit - The LUA script:

 --Ported to LUA from https://gist.github.com/tagliati/1804108 (Andre Tagliati)  
 --by AReResearch (www.areresearch.net) Andy Reischle  
 --Port index4=GPIO2  
 speakerPin = 4;  
 gpio.mode(speakerPin,gpio.OUTPUT)  
 --speaker connected port  
 --Tone table  
 t={}  
 t["c"]=261  
 t["d"]= 294  
 t["e"]= 329  
 t["f"]= 349  
 t["g"]= 391  
 t["gS"]= 415  
 t["a"]= 440  
 t["aS"]= 455  
 t["b"]= 466  
 t["cH"]= 523  
 t["cSH"]= 554  
 t["dH"]= 587  
 t["dSH"]= 622  
 t["eH"]= 659  
 t["fH"]= 698  
 t["fSH"]= 740  
 t["gH"]= 784  
 t["gSH"]= 830  
 t["aH"]= 880  
 --frequencies for the tones we're going to use  
 --used http://home.mit.bme.hu/~bako/tonecalc/tonecalc.htm to get these  
 function beep(pin, tone, duration)  
 local freq = t[tone]  
 print ("Frequency:" .. freq)  
 pwm.setup(pin, freq, 512)  
 pwm.start(pin)  
 -- delay in uSeconds  
 tmr.delay(duration * 1000)  
 pwm.stop(pin)  
 --20ms pause  
 tmr.wdclr()  
 tmr.delay(20000)  
 end  
 --Play it  
   --for the sheet music see:  
   --http://www.musicnotes.com/sheetmusic/mtd.asp?ppn=MN0016254  
   --this is just a translation of said sheet music to frequencies / time in ms  
   --used 500 ms for a quart note  
   beep(speakerPin, "a", 500)  
   beep(speakerPin, "a", 500)  
   beep(speakerPin, "a", 500)  
   beep(speakerPin, "f", 350)  
   beep(speakerPin, "cH", 150)  
   beep(speakerPin, "a", 500)  
   beep(speakerPin, "f", 350)  
   beep(speakerPin, "cH", 150)  
   beep(speakerPin, "a", 1000)  
   --first bit  
   beep(speakerPin, "eH", 500)  
   beep(speakerPin, "eH", 500)  
   beep(speakerPin, "eH", 500)  
   beep(speakerPin, "fH", 350)  
   beep(speakerPin, "cH", 150)  
   beep(speakerPin, "gS", 500)  
   beep(speakerPin, "f", 350)  
   beep(speakerPin, "cH", 150)  
   beep(speakerPin, "a", 1000)  
   --second bit...  
   beep(speakerPin, "aH", 500)  
   beep(speakerPin, "a", 350)  
   beep(speakerPin, "a", 150)  
   beep(speakerPin, "aH", 500)  
   beep(speakerPin, "gSH", 250)  
   beep(speakerPin, "gH", 250)  
   beep(speakerPin, "fSH", 125)  
   beep(speakerPin, "fH", 125)  
   beep(speakerPin, "fSH", 250)  
   tmr.delay(250000)  
   beep(speakerPin, "aS", 250)  
   beep(speakerPin, "dSH", 500)  
   beep(speakerPin, "dH", 250)  
   beep(speakerPin, "cSH", 250)  
   --start of the interesting bit  
   beep(speakerPin, "cH", 125)  
   beep(speakerPin, "b", 125)  
   beep(speakerPin, "cH", 250)  
   tmr.delay(250000)  
   beep(speakerPin, "f", 125)  
   beep(speakerPin, "gS", 500)  
   beep(speakerPin, "f", 375)  
   beep(speakerPin, "a", 125)  
   beep(speakerPin, "cH", 500)  
   beep(speakerPin, "a", 375)  
   beep(speakerPin, "cH", 125)  
   beep(speakerPin, "eH", 1000)  
   --more interesting stuff (this doesn't quite get it right somehow)  
   beep(speakerPin, "aH", 500)  
   beep(speakerPin, "a", 350)  
   beep(speakerPin, "a", 150)  
   beep(speakerPin, "aH", 500)  
   beep(speakerPin, "gSH", 250)  
   beep(speakerPin, "gH", 250)  
   beep(speakerPin, "fSH", 125)  
   beep(speakerPin, "fH", 125)  
   beep(speakerPin, "fSH", 250)  
   tmr.delay(250000)  
   beep(speakerPin, "aS", 250)  
   beep(speakerPin, "dSH", 500)  
   beep(speakerPin, "dH", 250)  
   beep(speakerPin, "cSH", 250)  
   --repeat... repeat  
   beep(speakerPin, "cH", 125)  
   beep(speakerPin, "b", 125)  
   beep(speakerPin, "cH", 250)  
   tmr.delay(250000)  
   beep(speakerPin, "f", 250)  
   beep(speakerPin, "gS", 500)  
   beep(speakerPin, "f", 375)  
   beep(speakerPin, "cH", 125)  
   beep(speakerPin, "a", 500)  
   beep(speakerPin, "f", 375)  
   beep(speakerPin, "c", 125)  
   beep(speakerPin, "a", 1000)  
   --and we're done \ó/  

The beep() function is the only moderately interesting bit. I had to insert a tmr.wdclr() to avoid problems with the watchdog timer. The rest is pretty much what Andre had prepared. Just in a LUA flavour.

The videos will appear on my Youtube channel shortly.
Here is the first video: https://youtu.be/dlnj3u-Tj3A