DIY Bluetooth Headset And Other Inventions

NETHED writes "Circuit Cellar has an blurb about a guy who obviously got sick of waiting for a cheap solution to the BlueTooth cellphone headset. So in true geek tradition, he rolled his own. Here is the description of the toy (which looks bulky as-is, but could be fixed w/ some refining). It actually didn't win any prizes in the PSoC contest, but you have to admit, its pretty cool. There are other honorable mentions like a poor man's O-scope to something that seems to attach to a moth and check its muscle movements. Neat and nerdy stuff for the circuit etching crowd."

Comments

Re:would this work for PC?

[mritunjai]

Sure It would. Only thing is that, PC output is stereo, so you'll need two ADC channels (already on the pSoC chip) to convert the analog outs into digital and xfer them to other side. However, the actual sampling rate (and hence audio quality) would be limited my bluetooth bandwidth.

For 16bit 44.1kHz stereo you'd need 1.411 Mbit/s speed... I'm not sure whether bluetooth can go upto that speeds. Though, for headphones, lower bit rates/sampling rate should not cause sigificant loss in quality (headphone speakers are already sucky) but would surely help making it feasible project

Re:bluetooth module

[Afrob]

Try www.btdesigner.com for bluetooth modules.
Exact documentation about how these things work still seems to be hard to find :-(.

Re:Why not simple RF?

[skinfitz]

I was talking about practical applications of this idea. If "security" is your concern, "forget" BT. The security it provides is worse than that of Wi-Fi.

I'd be very interested to hear you justify that. My BT headset is paired to my phone - it won't listen to anyone elses phone, and my phone will not listen to anyone elses headset. The phone and headset are not even discoverable unless I manually do something to them. Comms are encrypted and sent over spread spectrum. I doubt that the average phonecall lasts long enough to capture the gigabyte or so of network traffic that it would take to even begin to attempt to break the crypto, plus attackers would have to be within a 10m radius of my call which could prove to be a little difficult.

Re:What's the frquency, Kenneth?

[bobstay]

You should look into the power levels on these things.

Personally I'd prefer to stick 20mW @ 2.4GHz (Bluetooth headset) next to my brain, than 500mW @ 1.8GHz (GSM Mobile Phone)

Re:some questions

[Dielectric]

The PSoC can have three different types of A/D converters, with varying resolutions and speeds. For example, a 12-bit incremental will get a bit under 300 sps, a 6-bit SAR will get 333ksps.

No, no open source compilers yet. Only one from Image Craft. Actually, they are very responsive to bug fixes and feature adds.

There is no comparable part from any other manufacturer. This thing has incredible analog capability, such that you can filter those signals before you run them through an A/D, or any other of thousands of other analog signal chains. The chip is very flixible.

Re:would this work for PC?

[cmckay]

For 16bit 44.1kHz stereo you'd need 1.411 Mbit/s speed... I'm not sure whether bluetooth can go upto that speeds.

Bluetooth sends at 1Mbps (that's megaBIT), but the maximum data rate (after overhead) is 721Kbps. That maximum data rate can only be achieved through asynchronous communications-- you can send at 721Kbps but only receive at ~20Kbps (forget the exact number). Oh, and that's without error correction. I believe the maximum synchronous speed is about 300Kbps in each direction.