$50 machine to help end poverty

That would take a bit of research, since it'd be an analog audio signal, likely distorted some by going through some RC filters, which would need to accurately convert into a digital signal.

Sounds like a good idea though. Just need a super simple way of doing it.

Tony

It might be possible to use SMPTE timecode somehow, its a common and well supported standard bit of a different application though!... Your biggest problem with any audio playback type is going to ensure zero lag or stutter, any of that will ruin the build.

That said, its a very good idea!

On the receiving end it's basically a modem.

The trick would be encoding the modulation signal correctly into an mp3. Someone could hack this.

The instructions would 'play' in their entirety before printing began, with checksums etc. to make sure the transmission was correct. It's all quite feasible.

A modem would probably use up to much code. There's not much space on my unit. It'd have to be done in less than 1 KB I would say. Ideally a few hundred bytes or less, and little or no hardware. At least, that's how it'd need to be for my 3D printer. Anyway, modems are designed to send signals over very long distances on crappy wires. A direct connection to a phone is much cleaner. Something much simpler than a modem should be fine.

Another thing to consider is the amount of bytes per second of MP3, or bytes per MP3 byte. Need the MP3 to be small enough to fit on a cell phone, or there'd be no point.

Might be best to do it as an add on. As an add on it could have a dedicated MCU, and do some fairly elaborate decoding and get pretty high code density in an MP3. That way it wouldn't add anything to the cost of the 3D printer, 'cause I'm planning on having an external port anyway. There's also the advantage that such a unit could attach to other future machines as well. It'd likely be about a $5 device, I would imagine.

Tony

Ant, modems have existed for a looooong time. I'm certain there are tiny Assembler modem codes out there, I don't know about 1 kilobyte but realistically 5 to 10, the trick is finding them, as they would be older than the WWW by many years.

That'd be acceptable for an add on device, which I think it a better idea anyway. Also, using modem code would allow it to work via land phone lines, which adds more versatility.

Tony

Tony,

Would you like to start putting up files, napkin sketchs, PCB plans, etc. up on the wiki?

E.g. at
[objects.reprap.org]
or
[objects.reprap.org]
(I'm not very good at names, but it's a wiki, so you have a lot of flexibility.)

This will help you bootstrap off the RepRap community and integrate what we've got with what you've got. Then the folk here can chip in easily.