Forums

Bluetooth module help?

Started by Adam Kumpf June 17, 2005
Hello,

  I have done some work with Bluetooth modules in the past and have
connected them to microcontrollers.  However, I am still unclear as to
what the best module for my applications is.  My main point of
confusion lies in whether or not a "profile stack" is needed for simple
data connections.

  For example, I can purchase a $70 module with built in SPP (Serial
Port Profile) or a $60 module without it.  With the $70 module, hook-up
is fairly straigh forward.  Just talk to the module over UART/Serial.
If, however, I go with the cheaper module, how much more work do I have
to do in the microcontroller to talk to the module?  I'm sure this is
somewhat module-specific, but in general, how necessary is the "profile
stack"?  Is it worth the extra $10?

Thank you very much for your comments.

Best Regards,
  Adam Kumpf
kumpf@mit.edu

Here are the two modules for comparison:

  http://www.mangocommerce.com/btdesigner/department.cfm?dcode=74

(look at the 2nd module <EYMF2CAMM-XX (with Antenna)> and the 6th
module <EYMF2CAMM (UART)>)

Thanks again. :)

Hello,

> I have done some work with Bluetooth modules in the past and have > connected them to microcontrollers. However, I am still unclear as to > what the best module for my applications is. My main point of > confusion lies in whether or not a "profile stack" is needed for simple > data connections.
depends if it is a private project or a commercial project. And on the amount of pieces you want to produce. If it is commercial, you need a Bluetooth certification for your developed parts (Bluetooth stack), which is not cheap. Also a lot interop test are needed, if you want to be compatible. You already have an Bluetooth tester (Air Sniffer, HCI decoder...) ? Most important, also take into account the time (and amount of people) needed to write such a stack. If private project, you can just take the modules, create a ACL connection and transfer some data. But this way is not compatible to anything else ! Perhaps, to make your decision easier, download the Bluetooth Core Spec. and have a look at chapters HCI, L2CAP, RFCOMM. All these are needed to implement your Serial Port Profile... If yu have further questions you can contact me directly via email ! Regards, Martin
Thanks so much for the reply.

It sounds like $10 is a pretty small price to pay for greatly
simplifying the design of a proof-of-concept prototype.  The time and
cost required to implement my own HCI, L2CAP, and RFCOMM for a
bluetooth project is probably not worth it unless I end up wanting to
produce millions of these gadgets.

Your input was very helpful!

Thanks again,
  Adam
kumpf@mit.edu

On 17 Jun 2005 18:35:37 -0700, "Adam Kumpf" <akumpf@gmail.com> wrote:

>Hello, > > I have done some work with Bluetooth modules in the past and have >connected them to microcontrollers. However, I am still unclear as to >what the best module for my applications is. My main point of >confusion lies in whether or not a "profile stack" is needed for simple >data connections. > > For example, I can purchase a $70 module with built in SPP (Serial >Port Profile) or a $60 module without it. With the $70 module, hook-up >is fairly straigh forward. Just talk to the module over UART/Serial. >If, however, I go with the cheaper module, how much more work do I have >to do in the microcontroller to talk to the module? I'm sure this is >somewhat module-specific, but in general, how necessary is the "profile >stack"? Is it worth the extra $10? > >Thank you very much for your comments.
Unless you want to use these modules in huge quantities, $10 is peanuts to pay for the software stack. Also remember that the production cost for the manufacturer is essentially 0 for this software over time. So over time and with the competition one would expect they would drop this extra $10. Just for interest sake, which modules are you considering ? Regards Anton Erasmus