which bt module and shield?

hi, i need some advice here, I want to use Bluetooth for remote logging, and simple command control, especially STOP!!!

  1. Range
    I understand the Seeed BT module is class 2, I have a class 1 dongle which I have been testing with some other class 2 units I now get sufficent range indoors which is around 20 meters which is much better than the previous class 2 to class 2 I was using, do you reckon the seeed bt module would be similar in range to that? I know things vary but anyone have experience

(The dongles am I testing are using SPP serial coms)

  1. which BT module, bees, shields etc?
    a. I have a seeed mega, and not sure which way to go, pure BT module and build me own, bit of a pain or
    BT Bee, and a xbee shield ? but what about the UartSB?

b. I envisage needing to have work a bit at the AT sequences quite a bit (hahaha) so programming from a PC via something like the USARTSB but does this then allow for direction arduino connection and disable the USB-FDTI connector?

  1. Power and ttl-cmos?
    Powering the BT module is 3.3 volt but looking at the drawings for the shileds and bees they do not seem to have any 5V to 3V supply or conversion, just switches/jumpers labelled 5v or 3.3 could someone please explain, the drawing are n’t too clear.



edited for typos and clarity

Hi Dave,

Glad to know you are interested in the bluetooth module and shield.

The reliable distance of the bluetooth module/bee in seeedstudio is 10m also, however it may vary in different circumstance.

To control BT by seeed mega, I think use the xbee shield to connect BT Bee is the most appropriate way, as it doesn’t need extra connections. You can use the serial port(TX,RX)on mega to send command or receive data from BT. When the BT has been paired with the other BT, data sent from the mega will be transparent. So you can only disconnect the paired BT in hardware way as described in the datasheet.

UartSB is a very convenient tool that can be used by PC to control xBee, BTBee, RFBee,etc. You use a serial terminal run on PC to control the BTBee(http://www.seeedstudio.com/forum/viewtopic.php?f=4&t=687), or program a software which can control the BTBee in the way you like. All in all, they are using COM port.

The BT module and other Bees are all 3.3v power. So we do have voltage conversion in the xBee shield(we use LD1117). However, xBee shield v1.1 has stopped production now, and we are developing a new version Bees shield, it may be available in two weeks later.

May it helpful to you, and feel free to ask any question!

All the best,


thankyou for the great reply ICING!!

I saw the double bee shield, is there another variant coming?

will the new xbee shield have passthrough connections for the other seeed mega i/o pins, reason I ask is I am not using shields? SO I have a dogs breakfast ( not pretty) for wiring at the moment it should clean up with the BT as I can take off the lcd.

looks like an order is coming!


Any distance issued will be solved by placing my dongle high and central in the house…but I think by using the class 1 device, I should be ok

from the wiki:

USB 1.1 maximum cable length is 3 metres (9.8 ft) and USB 2.0 maximum cable length is 5 metres (16 ft).[34] Maximum permitted hubs connected in series is 5. Although a single cable is limited to 5 metres, the USB 2.0 specification permits up to five USB hubs in a long chain of cables and hubs. This allows for a maximum distance of 30 metres (98 ft) between host and device, using six cables 5 metres (16 ft) long and five hubs. In actual use, since some USB devices have built-in cables for connecting to the hub, the maximum achievable distance is 25 metres (82 ft) + the length of the device’s cable. For longer lengths, USB extenders that use CAT5 cable can increase the distance between USB devices up to 50 metres (160 ft).

A method of extending USB beyond 5 metres (16 ft) is by using low resistance cable.[citation needed] The higher cost of USB 2.0 Cat 5 extenders has urged some manufacturers to use other methods to extend USB, such as using built-in USB hubs, and custom low-resistance USB cable. It is important to note that devices which use more bus power, such as USB hard drives and USB scanners will require the use of a powered USB hub at the end of the extension, so that a constant connection will be achieved. If power and data does not have sufficient power then problems can result, such as no connection at all, or intermittent connections during use.

Hi Dave,

The new Bees Shield may be available two weeks later, and it has much connections from seeeduino (mega). You may have a reference here :http://www.seeedstudio.com/blog/2010/06/03/bees-shield-not-another-xbee-shield-but-two/#comments

All the best,


thankyou very much for the replies it has been very helpful and keeps me coming back to seeeduino