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

DIY

[Omkar]

And SciAm just ran an editorial lamenting the demise of DIY. I guess that these innovations need a higher profile if we are to encourage science and technology as interests for youth.

Re:DIY

[Anonymous Coward]

DIY pretty much died with BGA-packaging. None of the currently interesting integrated circuits come in DIY friendly "dual-inline packages" anymore. If you're lucky you can get SMD-chips with tiny contact distances, but chips aimed at mobile devices like Bluetooth controllers are only available as BGA (ball grid array) packages, which means you need either quite expensive tools or a great deal of luck, an oven and some spares of your board and the chip to experiment with. The DIY Bluetooth headset is built around a developer board for the Bluetooth controller for that reason. The chips may be cheap, but combining them to useful gadgets is now prohibitively expensive unless you want to produce thousands.

Why not simple RF?

[krazyninja]

Why do we have to design a BT based headset for this purpose? Does going digital add any advantage to this kind of application? I would imagine an advantage when the data transmission itself is digital, for example in the case of MP3 streams to a BT enabled headphone. But this..?????

Re:Why not simple RF?

[Suicide]

Does going digital add any advantage to this kind of application?

Just going digital, probably not. However, I can run to the local cell phone store and buy a phone with BT. Anyone know where I can buy a cell phone with a "simple RF" interface, that is standard enough to either build or buy a headset for it?

Re:Why not simple RF?

[matthew.thompson]

Bluetooth also includes encryption and authentication. Do you really want the guy in the seat next to you to answer your phone call before you because he has quicker reflexes and a "simple RF" interface headset?

Bluetooth is the ideal interface as it interoperates with other devices in the the area. I use bluetooth between an iBook and Nokia handset and I've never had any problems with the devices not connecting to each other.

Re:Why not simple RF?

[krazyninja]

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. On the question of interoperability, I fail to understand why a headset should be interoperable with other devices....

Re:Why not simple RF?

[Sycraft-fu]

Uhhh, because it's rpetty worthless if it doesn't? My Plantronics (corded) headset is useful precisely because it interoperates with my phones (both cell and cordless). If it didn't I wou;dn't want it. Well many (most?) new cell phones are comming with Bluetooth built in. Hence, it's a convienent way to communicate with them. If a company makes a Bluetooth headset, they know that there will be a fair market for them because there are many cell phones that support the same standard.

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:Why not simple RF?

[photon317]

I can't speak to specifics, I haven't started digging around BlueTooth yet, but don't be so quick to deny it's hackability based on the market drivel you've repeated. 802.11X protocols also had various mentioned feautures to make them secure - and as long as everyone just runs their factory cards/drivers/software/settings, it's secure. But if your security relies on someone not re-writing the software, you're SOL. Check out http://802.11ninja.net, where some freinds of mine have some software the defeats just about everything that 802.11X offers security-wise. With that software and the right card, you can DoS a base station, join a supposedly "secure" network, launch a man-in-the-middle attack (you become the base station to the network's users), and yes, even recover the weak crappy keys that the protocol uses for encryption and do al the same irregardless of that encryption.

So again, the question is not what market drivel buzzwords someone said about the technology - technically if 802.11 had implemented all their buzzwords correctly they would be secure too - it's about whether they really did it *right*, or they left it poorly implemented and vulnerable. So far history is on the vulnerable side.

Re:Why not simple RF?

[skinfitz]

802.11X protocols also had various mentioned feautures to make them secure...

I am well versed in 802.11b hacking techniques, and I agree totally that it is extremely vulnerable. Due to flaws in the design it is literally not possible to secure an 802.11b network - it can be compromised so much so that you might as well put wired LAN access ports on the outside of your building with flashing neon signs pointing at them saying "plug in here". The biggest weaknesses of course being that it doesn't encrypt the beacon frames and the fact that there is a certain packet that can be broadcast that will DoS all devices in range.

This doesn't however, relate to Bluetooth which does not work in the same manner.

Even in the event of no other security, I think the strongest security "feature" of Bluetooth is it's short range, plus the fact you cant connect to some devices unless the user / owner manually sets it to discoverable mode.

I'm not naive enough to assume that this is unbreakable however, but the range thing itself makes it more "secure" than 802.11b.

would this work for PC?

[Anonymous Coward]

I've been trying to find for a long time an inexpensive wireless headset for PC... but obviously I was too optimistic.

However the schematics of the mobile phone headset look like they could be modified to work as PC head- and micro- phones.

Any ideas? I might dig out my old solder iron if this is possible... :-)

(dream mode) Finally... a wireless PC phone... :)

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: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.

Great Idea

[denisonbigred]

A cordless headset is really important too, since my cell phone is so BIG that its hard to carry around with me. Right.

Re:Great Idea

[cosyne]

I'd like to have a headset that switches to the best avalable carrier, be that my cell phone, the landline in the lab (where my cell phone doesn't work), 802.11 VoIP, or maybe directly to the headset of the person i'm talking to, if they happen to be in range. Actually, i'd rather that my cell handset did this, but since Cingular covered $200 of it, i don't see it switching to landline or 802.11 VoIP anytime soon.

Re:Great Idea

[cosyne]

no, i don't really think that cingular cut handspring a check for $200. Yes, it's all markup. It's all about the MAN trying to squeeze as much profit out of me as possible. That's how capitalism works. If, in general, more people buy things when you price them at $600-$200=$400 (but you still have to pay sales tax on $600) than if you just priced them at $400 to begin with, then that's how things get priced.

The point, though, is that cell phones are not sold for profit. They are given away/subsidized so that service providers can profit on service (which is not a bad business model, until someone chips the harware and fucks with you profit stream). But no service provider is going to subsidize a phone which is designed to aviod using their service whenever possible.

Re:Great Idea

[rosewood]

Fuck, the way the Tmobile networks have been acting up, I would LOVE to be able to use the AT&T networks around here ... won't let me tho

Daddy...

[xsfo]

Daddy, what's circuit etching? :P

Wierd Results

[mritunjai]

OT: But is it just me who finds it wierd that a simple Ultrasonic Distance meter won first prize whereas other more useful devices were dumped ?

eg. See this Ultra sonic mapper which does all what the No. 1 does plus MUCH more, and Geeky Keep-in-touch device.

May be their stress was on purely pSoC based systems (No. 1 doesn't have any other semiconductor device than pSoC). Even if it was this, they should have mentioned this in their competition.
I all my impression is that creativity and effort has been brushed aside in this competition.

Regards
- Mritunjai

Re:Wierd Results

[mistered]

Circuit Cellar has been running these types of contests for ages. They're sponsored by some microcontroller company e.g. Atmel, Microchip, etc. and although it's Circuit Cellar staff that do the judging, there's usally extra points for designs that really show off the featured part for the contest.

This is from the PSOC contest description:

Any working electronics project based on the Cypress PSoC(TM) MCU (CY8C25xxx/26xxx family). Innovation, architectural elegance, and quality of design were key factors in the PSoC(TM) Design Challenge 2002 Contest. Entries ran the gamut between proven and leading-edge technologies. From very simple to the most intricate, winning was not a function of complexity.

Bonus consideration was given for the most effective use of internal hardware integration, the most effective use of dynamic reconfiguration, and the most novel application.

WOW!

[ctar]

This entry won 2nd place, and for good reason...Here's the gist of it:

This device sits in between your TV and your cable or antenna source. It strips out the close captioning information, and replaces it with custom information from your PC and/or caller ID, and prints it as a headline on your TV using the close captioning feature.

He says the box itself can decode caller ID info from your phone, and has a wireless link to get IM or 'You've Got Mail' type updates from your PC...Pretty sneaky. er...Geeky

The problem with headsets is the battery life!

[seamustheshark]

I have a dinky-little SonyEricsson headset for my Nokia 6310, and even after being fully charged, the battery in the thing only lasts around four-to-five hours in its 'standby' mode.

If actually used to make/receive a call, the battery life is even worse!

So, in all, a nice gimmick, looks lovely, but almost completely useless as it won't last the duration of a working day.

(And, of course, there's no 'in-car' charger available!!)

Re:The problem with headsets is the battery life!

[Anonymous Coward]

Take the the battery out of the phone and drop it on a hard wood or concrete floor from a about 2ft to 3 ft. This will should shatter the crystals that have formed around the terminals in the battary. This only goes for Nickel-Cadmium and Nickel-Metel-Hydride if I remember correctly. This should counter act the memory effect of this batterys.

That's not really the idea

[Sycraft-fu]

They don't have a long range or anything. The thing is there are often times when you want to be able to use our phone, but not be holding it to your head. Driving comes to mind. Hence, a headset. Now it's near enough that wires work, however they are not real conveinent. Hence, a wireless headset. Yes, it's not real necessary and is kind of a toy, but hey, we like toys.

bluetooth module

[MenAtWork]

I tried to stake out digikey to see if i can buy some bluetooth module, doesn't seem like, does any one know where to buy bluetooth modules. Also I find it surprising that the part number for the bluetooth module was the only thing not mentioned in the project details.

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 :-(.

You think that is classy?

[stefanor]

How about our brick mod.

The transformation of an old (semi-brick) phone into a fully-fledged brick, complete with 3-prong plug!

Check it out at http://brick.rivera.za.net/ now that is what I call a mod!

some questions

[g4dget]

The information on the Cypress Micro site is nearly unreadable: it's a big PDF document squeezed into a tiny frame, with no datasheet summary. I'm wondering:

• What's the resultion and speed of the D/A and A/D converters?
• Are there any open source compilers that work with these chips?
• Are there any comparable chips from other manufacturers?

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.

Some bluetooth stuff I want

[rosewood]

Sure, I want my cellphone and PDA bluetooth'd so that when I come near the two of them sync with my PC so all my shit is together, so to speak.

I also really want the bluetooth earpiece so I look like even more of a loon then I do with my hands free.

I also want bluetooth locks on my door and my car. Oh you say wait until your 1337s hit me and break in ... make the encryption key strong enough (can be generated on my box and just sent to phone so the phone doesnt have to gen it) so its not possible. The point of these is so whenever I get to my door, the house unlocks or when I get to my car, its unlocked.

I also want the ATMs and Vending Machines Bluetooth enabled. I just worry about the Vending Machines getting used more by me when I dont have to watch moneys go into it.

Yes, bluetooth enabled TV/Receivers. Truely universal remotes.

Bluetooth enabled appliances. Control the hot and cold from my PDA, start the oven, etc. (Again, like all of these, you just need strong encryption. ALso, bluetooth is short range so I war chalking shouldnt be much of a problem?)

Please, someone start this REVOLUTION already ):

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)

other oscope solutions

[bcboy]

xoscope -- for a totally cheap solution (uses audio-in on your soundboard).

bitscope -- a more serious microcontroller-on-the-serial-port solution.

you can find them from google.

In the future...

[falzer]

Daddy, what are discrete components?