Let there be sound
"DING DONG, the failure you have ordered has just arrived." /#ele
- 1 The concept
- 2 Let there be sound!
I want an AVR to talk to me. No need for it to speak words... i just want a DING DONG sound, or two. Or three. I want it to alert me in case one of few events occurs, and I want to be able to determine which event occured by just hearing it. A lot? Let's see...
Searching for tone generation app notes leads to some decent solutions, yes. A 8MHz crystal, varying PWM fill ratio, a lot of math, etc. Gimme a break, it's sunday damnit. I just want to hear it working.
Why can't one make it simpler?
Let there be sound!
The base setup
I'll be using tiny2313 by atmel for this one. And a vera-board which is SOOOOOO nice (not). Some pics follow:
Concept #1: PWM + speaker
The most basic setup of all. A 8Ohm 0.25W speaker with a current limiting resistor in series (360Ohm) driven by a PWM output.
One can hear it, yes. From very close range, in a quiet room. Some frequency/fill_ratio settings seem like a good base to work from. But I need something louder - this could only alert me around 3a.m. if it's supersilent in the whole block and I am awake already. Scope pics not worth downloading, too. Neeeeext!
Concept #2: PWM + piezo w/ builtin generator
Here's a PWM output driving a piezo element integrated with a generator. Will it blend?
This is at least loud! It wont shatter windows, but it could surely do as a doorbell. Or some other simple alert of a similar kind. This sounds like my old atari 65 while the tape player was being adjusted. Not sure I liked it *that* much...
Concept #3: R/2R DAC