This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

replacing SPP BT module with CC2540

Other Parts Discussed in Thread: CC2540

Hi,

I am new in BLE so I need advice. My company uses SPP on BT module along with MSP430 for long time, and we want to transfer to cc2540 chip. Our device communicate to PC over BT USB dongle via virtual comm port (SPP), and to another BT module using same profile. 

Is it possible to switch to CC2540 and to keep both communication capabilities, and if not what is required to?

 

Mirko

  • BLE does not have anything like the serial port profile, and would not be a very good choice of wireless technology if you are sending a high amount of data and need it sent with low latency. All data communications within BLE are done using the ATT / GATT layers of the protocol stack, which allows for a maximum of 20 bytes per packet. If you really want, yYou could implement software that fragments your serial port data into 20-byte chunks and then defragments the data on the other side; however we do not have any existing source code or profiles that do this.

  • Does that means that CC2540 cant get connection with any of standard USB BT dongles? And second, what is maximum data throughput that BLE or CC2540 can achieve?

  • Mirko,

    The CC2540 can only communicate with Bluetooth 4.0 devices that have LE support, not with Bluetooth 3.0 or earlier. The maximum practical throughput of LE is something around 100 kbps. If you start to approach this, you are not going to get any power benefits by using Bluetooth LE, so you might as well use "classic" BR/EDR.

    Best regards,

    Karl

  • Hi Karl,

     

    100kbps works for us and low power too. Only thing that worries me is pairing device - so far we used USB BT adapter or BT module 2.0, 2.1+EDR etc. but now we should have 4.0 and I dont see them commercially available. Do you know about some commercially available BT 4.0 devices? What about android phones - does any of them have 4.0 BT port?

     

    Thanks,

    Mirko

  • Mirko,

    I am not aware of 4.0 dongles being commercially available yet, no. This is also true for phones. I do expect both 4.0-enabled USB dongles and phones to be available later this year.

    Karl

  • Hello. I have a question about the BTLE profiles. What BTLE profiles are now available and what BTLE profile is suitable for data transmission, similar to the SPP from earlier versions. What other specialized profiles are implemented by CC2540 next to GATT and CAP.

    Thanks

    Michael

  • Hello,

    I have the same question as Michael and I have seen also that nobody have answered to Michael.

    Why the new BT version ? I can not see the actual benefices. I think that also the old BT can be "low energy" using the same profile or adding the new ones without eliminating the old ones.

    Thanks

    Ben.

  • Wow.

    "Why the new BT version?"

    BLE is a try to make Bluetooth suitable for point-to-point Wireless Sensor appliances, for example. BLE is NOT designed for large data transmissions such as SPP but for small amounts of data that would use too much energy per bit (and latency) if transmitted in traditional BT.

    "I can not see the actual benefices"

    Try to make a cell button battery last for 2 years with traditional Bluetooth :) BLE is also simplified. Have you ever used the scatternet function in BT? Me neither. There are plenty of things BT was not able to do in a traditional manner because it was too much power consuming. These are now enabled by BLE.

    "I think that also the old BT can be "low energy" using the same profile or adding the new ones without eliminating the old ones".

    We can also take a "Kawasaki Ninja" motorcycle, get rid of the engine, put some pedals in it, and use it as a bike. It does not pollute and is low energy, but you are not being released of a lot of things you do not need ;) You cannot use the same thing for BLE, since for example RF channels in BT are 1MHz width, in BLE 2MHz. The L2CAP layer and even the connection event thing is different. If not, the drastic reduce savings in BLE would not be achievable.

    Bye! :)