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Embedded Bluetooth module VS USB dongle

I'm currently running an embedded (OK, a small) PC that collects data from the parallel port and sends them via bluetooth to a central machine. I'm considering changing to a 'real' embedded device, partly because I'd like the experience, partly because the power consumption of the PC is too high for the job it does and mostly because it's too big.

The basic configuration I've sketched out on the back of the proverbial envelope is a PIC 18F4550 (I'm already familiar with PICs and I've got some of these chips) with an FTDI Vinculum chip hosting a USB Bluetooth device because the Bluetooth USB dongles are considerably cheaper than OEM Bluetooth dongles although all of the dongles I've pulled apart have had a module fitted to a base board.

My question is, would it be *much* easier to use a BT module than the dongle, I may want to be able to attach more storage in the future so I can log data outside the range of Blue tooth so the FTDI chip looks nice from the point of being able to attach a simple USB flash device as well although I could just attach an SD/MMC card to the PIC.

If the dongle route is 'do-able' Can anyone point me to any documentation that would give me an idea of what's involved in driving a USB Bluetooth dongle? In fact, even if it's not, I'd still like some kind of idea of what's involved even if I don't end up using the information straight away.

Obviously, if the USB dongle route is stupidly difficult compared to the oem module I'd be open to recommendations for a module with good code examples and/or good documentation.

Thanks in advance.

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Clint Sharp
Reply to
Clint Sharp
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Check with FTDI to see if they support USB BT modules yet.... They didn't when I suggested it to them last year. In principle they ought to be able to, as, unlike many other USB devices, there is a well-defined standard USB interface to the Bluetooth HCI layer so they shouldn't need any manufacturer-specifics. However you probably want a layer or 2 above HCI, so you may need to implement this yourself.

This is where 'proper' OEM BT modules score in terms of ease of use. By the time you've added the USB chip and surrounding bits, an OEM module isn't going to cost much more, but if the USB can have other uses this may swing the decision.

I've used the The Bluegiga WT11/WT12, which have a nice ASCII wrappper interface, and the WT11 is a Class 1 module - OEM modules don't often come in C1 versions. The Bluegiga modules are a bit on the expensive side however.

These are the cheapest USB modules I've seen so far :

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Seem to be fairly profile-specific though.

Reply to
Mike Harrison

The Vinculum approach sounds cooler but if you want a BT-only recommendation I've tried the NSC LMX9830 UART/BT converter and it's very easy to use.

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Andrew

Reply to
andrew queisser

Yes. I use the modules from Ezurio (former TDK). These are controlled and configured by AT style modem commands. One configured (15 AT commands to be sent only once), these modules don't need any intervention from the controller anymore. The moment a PC or other BT host pairs to it, your serial channel is up.

Meindert

Reply to
Meindert Sprang

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