Mac Serial to microphone

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doug-doug the mighty's picture
Joined: Apr 14 2004
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Okay, I realize that this is really left field, but I have to ask...

Is/was there such an animal as a microphone that was designed and built to interface to a Mac serial port?

I trust there would probably be special software for such a creature to function, so this would be helpful to share if you know as well.

In the event that none exists, what must I do to build my own?

I have never done anything like this, but I have a special application for which a serial based microphone is the best possible soultion. If it exists, that helps, if I must build it, that sux, but learning could be fun.

TIA
--DDTM

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--DDTM ('Fritter Critter' since Apr 26 2004 - 18:16)

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eeun's picture
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Closest thing I can think of

Closest thing I can think of was that Geoport Telecomm Adapter. Fun for voice mail and hands-free back in the day, though I was told that I sounded like I was at the bottom of a cave when on Geoport hands-free.

'Course, that's only for Macs with the enhanced Geoport serial port.

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Eudimorphodon's picture
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Wow.

What application could this possibly be, just out of curiosity?

If you have a computer fast enough to keep the serial buffer empty I suppose you in theory should be able to do sampling using a serial port. In block form I can picture tying an 8-bit D/A converter directly to a UART, with an appropriate crystal/timing circuit, wired up so the D/A converter will push a sample into the UART's output buffer whenever the "Data Ready" signal indicates it can take a byte. At 115,200 baud that'll give you a 14.4k sample rate.

You'll need some fairly real-time software to keep the recieve buffer on the recieving computer clean and to reassemble the data stream, but, well, thinking it out it sounds "doable". Assuming sufficient hardware and software talent on your part, that is.

--Peace

doug-doug the mighty's picture
Joined: Apr 14 2004
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Newton audio in...

Eudimorphodon wrote:

What application could this possibly be, just out of curiosity?

I am thinking it would be nice to build a special piece of hardware for a Newton MessagePad. Specifically, the MP 130. This, and earlier models, lacked a microphone but had a serial port.

Eudimorphodon wrote:

If you have a computer fast enough to keep the serial buffer empty I suppose you in theory should be able to do sampling using a serial port. In block form I can picture tying an 8-bit D/A converter directly to a UART, with an appropriate crystal/timing circuit, wired up so the D/A converter will push a sample into the UART's output buffer whenever the "Data Ready" signal indicates it can take a byte. At 115,200 baud that'll give you a 14.4k sample rate.

My target here is most likely going to be sub 14.4k sample rate. While I do not hope to do high end audio with this, I do hope to be able to feed intelligible voice data into my Newton. There are a number of apps that exist for capturing audio on a Newton (like Voice Notes, which is out of the box functionality on the MP2000), so it should just be a matter of writing a small piece to translate serial to the internal register/buffer of a given application to tell the NOS that a microphone is present.

Eudimorphodon wrote:

You'll need some fairly real-time software to keep the recieve buffer on the recieving computer clean and to reassemble the data stream, but, well, thinking it out it sounds "doable". Assuming sufficient hardware and software talent on your part, that is.

--Peace

The ideal application is to build a telephone capability for a Newton, that does not already have a microphone.

Ya' see, in my crazy little head, I want when I connect my Newton (I have a few different models) as a fax machine using a modem PC card, for the Newton to not look for a handshake, thus letting me manually connect and disconnect like a telephone. This idea is problematic for my 130 and 110, so if I could find a hardware solution to provide a microphone for these, then it is just a matter of software.

That being said, if I am writing an app that must be compatible with NOS 1.x and higher v. NOS 2.x I may do things a little differently. The end goal is an application that lets the Newton become a telephone (albeit a speakerphone). The matter of a serial-to-microphone piece is directly in support of this app running on non-mic-equipped Newtons.

This may become a on-hold project like my Eudimorphodon Challenge Card for my dead Quadra 950 (both of them), but since I spend a good bit of time with my Newton lately, it is something I want to explore further.

And for someone wondering why I would want a Newton to be a telephone, my thinking is that if I can get this to work, then the app should not know the difference bewtween a psuedo-modem connection through a PC card v. a psuedo-modem connection through a GSM PC card, making the Newton into a cell phone without the need for an earpiece.

So, for the sake of argument, let's assume that the computer is initially a newer Mac running OS 8.x and a standard (non Geo-Port) serial port.

Once the deviece is known to work, we can then determine what changes must be made to work on a slower (20 MHz) computer that is expecting low quality audio at sub 14.4k sample rate (this being a Newton). If it can be made to work, then writing the software for the Newton becomes easier.

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serial digitizer

Back in the day there was a serial-based audio digitizer, tho I'm dangity-danged if i can recall the product name. Prob something clever like MacMic . . .

dan k

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Farallon Macrecorder

...is the device you need to look for.

doug-doug the mighty's picture
Joined: Apr 14 2004
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Thanks.

I will start a WTB thread for this and will keep an eye on eBay, but if anyone can enlighten me as to how to build by own, I would be tickled pink...

I also noted that the software is available on UNNA (at least what I would need for this).

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--DDTM ('Fritter Critter' since Apr 26 2004 - 18:16)

'If it ain't broke, take it apart anyways. If you can't take it apart, break it so that you can fix it.'

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Re: Thanks.

doug-doug the mighty wrote:

if anyone can enlighten me as to how to build by own, I would be tickled pink...

Just to note, this is a much easier project then some of your Quadra ideas.

Here's a great start:

http://www.csee.umbc.edu/~plusquel/310/slides/8086_IO4.html

Take the audio circuit at the bottom of the page, and hang it off a UART like the one on the top of the page. (That's a bit of an oversimplification, but not much.) If you do without hardware handshaking you could probably dispense with needing a microcontroller or anything to play nice with the status registers. By dividing the baud rate generator output you can derive the signal to trigger sampling on the ADC. Then you just need a brain-dead buffering circuit to read the output from the ADC once it has a sample and stuff it into the transmit buffer of the UART.

Of course, a 16550 is "old school". Today there are very cheap microcontrollers that have both UARTS and ADC converters built into them. If you used one of them then the circuit literally becomes a chip and a few misc buffering/amplifier components. You just need to write some software.

Anyway. I won't comment on the problems you'll encounter in getting a "dial tone" out of a GPRS data modem. Good luck with your project.

--Peace

doug-doug the mighty's picture
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Thanks!

Good stuff!

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--DDTM ('Fritter Critter' since Apr 26 2004 - 18:16)

'If it ain't broke, take it apart anyways. If you can't take it apart, break it so that you can fix it.'

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I remember back in the heady

I remember back in the heady days of Amiga superiority there were many hacks for building serial digitizers (and connecting MIDI synths to the serial port too) so you might look at some of the hacks on AmiNET. They shouldn't be too hard to convert to a Mac serial port, and software would be a whole other story...

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You'll all kill me for this..

But I threw one of them (Farallon MacRecorder) out about a month ago, since they were fairly common devices.

I did however keep a device called the "MacVision" from Koala Technologies, mentioned here - http://www.atarimagazines.com/compute/issue60/188_1_REVIEWS_MacVision_For_Apple_Macintosh.php

I have a working 128k and 512kE, and the driver disks for it, so I should have a play with it some day Smile

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doug-doug the mighty's picture
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Re: You'll all kill me for this..

duck wrote:

But I threw one of them (Farallon MacRecorder) out about a month ago, since they were fairly common devices.

A rubber duck bath toy will be burned in your stead...

duck wrote:

I did however keep a device called the "MacVision" from Koala Technologies, mentioned here - http://www.atarimagazines.com/compute/issue60/188_1_REVIEWS_MacVision_For_Apple_Macintosh.php

I have a working 128k and 512kE, and the driver disks for it, so I should have a play with it some day Smile

This is cool, however my target application is to add a audio device to Newtons not already having a microphone/audio input. The thought of a video device to possible capture snapshots is intriguing, but too far off for me at this time.

Next time, do not throw stuff out, post it on the forums as FS/FT (For Sale/For Trade), someone may just pick it up for the novelty, of out of true need. When something works and you do not need it, someone else may benefit from it.

[shakes finger in scolding manner] BAD! BAD MAC-HOARDER! [/shakes finger in scolding manner]

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--DDTM ('Fritter Critter' since Apr 26 2004 - 18:16)

'If it ain't broke, take it apart anyways. If you can't take it apart, break it so that you can fix it.'

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Yeah

I feel bad about throwing out old Macs (which is why I have about 19..) but I live in Perth, Western Australia. Shipping from here to anywhere is likely worth more than the device in most cases :/

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That sounds an aweful lot lik

That sounds an aweful lot like the old NewTek DigiView dongles that I still have for my Amigas. I even still have the (automatic!!!) motorized colorwheel to use with them. Those were seriously heady days to get an actual live image into a computer, long before digital cameras made it a ubiquetous thing.

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