Eh, looks like there is a bug in the first top post that make the quality worse ...
* jimbauwens goes change the top post

Edit, sorry for the double post!

Edit2: video:

You need to connect the speaker (or headphone) between the TX and the GND pins on the dock port.

This picture shows how to connect the speaker (Credit goes to TI BANK):



Edit: better picture, thanks Critor!

Here is a little piece of code to play Happy birthday with Lua from your nspire:

TONE_LOW = "\001"
TONE_HIGH = "\255"

happy_birthday = {262,0.5,262,0.5,294,1,262,1,349,1,330,2,262,0.5,262,0.5,294,1,262,1,392,1,349,2,262,0.5,262,0.5,523,1,440,1,349,1,330,1,294,3,466,1,466,1,440,1,349,1,392,1,349,2}

function freq_key(key)
--return 440 * math.pow(2, (key-49)/12)
return key
end

function keytone(key)
local am = 57600/freq_key(key)
return TONE_HIGH:rep(am) .. TONE_LOW:rep(am)
end

function key_am(key, ammount)
return keytone(key):rep(ammount)
end

function key_time(key, time)
return key_am(key, freq_key(key)*time)
end

function play()
local out = ""

for i=1,#happy_birthday,2 do
out = out..key_time(happy_birthday[i]*5, happy_birthday[i+1]/10)
end
print(out)
end

function on.timer()
    play()
    timer.stop()
end

function on.paint(gc)
    timer.start(1)
end

However, the quality is not so good, because I can't send a byte that contains only 0's, and there is a stop bit at the end of each byte I send (I think). But its ok, you can have fun with it :p

I currently connect a directly a little speaker between the TX and the GND pins of my nspire, but I do not know if this is so safe. Should I add an diode in between?

Yeah, he still can do that.
But my point is that its not like the other time, where to forum was not so easy to backup.

Anyway, I almost can't understand how he doesn't see that you guys are just trying to help him. I don't know all his details though. I think he just doesn't want to lose his power, and sees Critor as a threat.

ephan, I have the basis of a game, with smooth scrolling. Its actually intended for the contest, but I haven't had much time to work on it

The speed is 115200 baud.
I'll try to make a little example soon

Well, you need to think how the character looks in binary, and try to make waveforms with it. Not so easy, but I'll try to make a simple library one of these days to make it simple

You can only send data with one port on the serial port, as the other one is input (you can't use it in Lua)

Loulou, nice to see you here on Omnimaga

I have playing around with the serial port on the nspire, and by sending large chunks of data to it (using print), you can make some sound. The problem is that you can't do anything while it is busy
Or ... you can hook up an arduino, and let that do the sound processing