View Full Version : Microphone code & schematics for the Prop?

12-31-2008, 08:14 AM
Hello all,

Alright, my bot can talk, soon will be able to see, now hearing... I have absolutely no idea how to interface a microphone to a prop or anything for that matter, let alone program it haha so I need a crash course and some resources for how to let the propeller read a microphone input please? http://forums.parallax.com/images/smilies/tongue.gif·Prefirably some schematics and maybe code examples?


Austin Bowen,

Robo-freak.com (http://www.robo-freak.com)
www.livesoundforum.com (http://www.livesoundforum.com)

"One must watch out for mechanics. They start out with a sewing machine, and end up with the atomic bomb" - A quote from someone that I saw on Addall.com

"Not only do I see the glass as half empty, I wonder if anyone poisoned the glass with arsenic" - My dad, inside joke haha

Mike Green
12-31-2008, 08:21 AM
The Demo Board has a built-in microphone and the schematics are posted on the Propeller Downloads page of the website. There are some sample programs that come with the Propeller Tool, one that just copies the digitized sound to the headphone output and another that graphically displays the sound at the microphone.· I think there's another program in the Object Exchange.· Start with all that.

12-31-2008, 08:55 AM
As usual "Mike is right." .... but you mention an important issue. There actually is no third party source of microphone solutions or speakers... although with speakers you can just ignore the hardware and hook it all up to your prop.

But microphones are a different issue... go ahead build your own circuit... do it just like it says in the cookbook... IT WONT WORK... seems to require an engineer or devoted amateur.

I know this because I'm not an engineer and I tried... not being a devoted amateur I don't know what to do next!

Partsman where are you?


12-31-2008, 09:07 AM
Where is the need?

Well... I have a cell phone g- something... that I would like to talk over. Singing monks works great... So all I need is a microphone hooked to a Prop and the Prop hooked to the phone and I'm up and talking to the world. I tried the circuit that the manufacturer suggested... it don't work:(

Beau Schwabe
12-31-2008, 12:19 PM

The microphone input uses a sigma-Delta style input and can be tricky if the circuit is not balanced correctly... The best approach is to design this particular part of the circuit as close to the drive and feedback pins as possible to avoid any unwanted parasitic capacitance effects. The microphone used is a typical Electret style microphone. Here is a link to one that I have used in th past... search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=668-1155-ND (http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=668-1155-ND)

Beau Schwabe (mailto:bschwabe@parallax.com)

IC Layout Engineer
Parallax, Inc.

Andy Lindsay (Parallax)
12-31-2008, 02:19 PM
I've been using one I got at Radio Shack for prototyping with the PE Kit. More info here:

http://forums.parallax.com/showthread.php?p=773150 (http://forums.parallax.com/showthread.php?p=773150)

Andy Lindsay

Education Department
Parallax, Inc.

01-05-2009, 10:59 AM
Thanks guys.

I'll give it another try.

Have been rearranging my prop room... not exactly a New Year's resolution but badly needed... am sitting on the floor looking at a tangle of wires that is beginning to look like a gordian knot to me:)


Am planning to make my work desk out of plumbing supplies:)

My hope is that someone (partsman) will come out with a reliable mini-board:) Circuits and me just don't get along unless someone else does ALL of the thinking:)

The Prop is by far the best decision I ever made.

Belated Happy New Year to everyone at Parallax.