Speaker

Status
Not open for further replies.

AtomSoft

Well-Known Member
Hello all i want to make a alarm which is pretty simple for me but i would love to be able to drive a small speaker for the alarm sound instead of a buzzer...

Can anyone point me to how to control a speaker. How to get different tones and stuff from a MCU pin...

Can be AVR, PIC, ARM i dont care really. Its all the same to me heh...
 
You simply set the pin high, wait a time, set it low again, wait a time, repeat.

The time you wait determines the frequency.

You can use timers to do it as well, and there's a website that shows how to play phone ring tones on a PIC using timers, written in C.
 
Do not just connect a speaker voice coil from a PIC pin to ground. The DC resistance of the speaker is so low that it will overload the port pin. Put a 100uF or so electrolytic capacitor (6V, properly polarized) in series with the speaker. This breaks the DC path so no DC current is drawn from the PIC port pin.

I would also try to find a 2" speaker with a 30 to 45 Ohm voice coil (they exist), rather than using one with a 4Ohm coil. It will make more sound and load the pin less.
 
I think i get it...Ill give it a try... so a 100uf in series like:



Then pwm a tone in and if i want... like...

BEEP----BEEP----BEEP----BEEP----BEEP


I have to pwm a tone in then delay then tone then delay.. etc.. correct?
 

Attachments

  • speaker.jpg
    6.2 KB · Views: 423
Last edited:
ahh yeah heh.. thanks... actually if they figured out that electricity goes from NEG to POS it would have been correct heh...

New Schem...


Thanks a bunch guys ... im about to go collect some old parts... like old cordless phones and rip some speakers out to test with heh
 

Attachments

  • speaker.jpg
    6.5 KB · Views: 394
Last edited:
No, electrons go from negative to positive; electricity goes from positive to negative.
 
i have those but wouldnt get the loudness i want or if i want to add MP3 capabilities in the future...

I am sure i can build or buy a prebuilt tiny amp if needed. if anything i could always test a mini amp (LM386)

Thanks tho.
 
Last edited:
thanks futz but that kind of confused me heh... i never understood asm like:

movlw 256 - (250-4)

what the heck would be in w ?
 
AtomSoft said:
thanks futz but that kind of confused me heh... i never understood asm like:

movlw 256 - (250-4)

what the heck would be in w ?
Click to expand...
Heh You got a calculator between your ears that will do that one easily.

Lucio Di Jasio has some good audio info in the last chapter of his "Programming 16-bit Microcontrollers in C" and the 32-bit book as well. I know you have a copy of the 16-bit book at least.
 
Last edited:
I have both heh... didnt even notice these books ... i forgot i bought the "Programming 32-bit Microcontrollers in C Exploring the PIC32" when i first wanted to get into PIC32 but went to arm heh...
 
I have a question about the inductive spike from the speaker coil. Given the high dv/dt of the PIC PWM signal, can anyone explain how the inductive spike from the coil is handled without a flywheel diode? Or is it assumed that the built in diode in the PIC handles the spike?
 
A capacitor there DC blocking You don't want a diode across a speaker
 
Last edited:
Status
Not open for further replies.

Similar threads

E
MTS51 speaker schematic
Replies
0
Views
2K
evol_w10lv
E
remote controlled speaker volume
2
Replies
34
Views
6K
4pyros
piezo speaker for mcu
Replies
2
Views
1K
Mosaic
J
Driving a speaker (or headphones) with ARM (LPC2138)
Replies
1
Views
6K
پروژه های الکترو
P
Speaker Confusion
Replies
14
Views
2K
Sceadwian
Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…