Bluetooth LE Development

28 Mar 2014

Looks like this is a good place to ask a question.

We are working on something related to BLE. But quite confused to go with TI or with Nordic.

We are in the process of ordering the mbed kit as well, but any suggestions on what are pros and cons?

Thanks, Krishna Kanth

28 Mar 2014

Overall, the Nordic SoC is better. Its technical specs are similar or better in the various aspects that one can compare SoCs. The price is lower for the Nordic chip. Working with this chip with BLE as of now involves using their precompiled binary. Its performance is not bad, but its like working with a black box, meaning you won't have any flexibility to improve or change anything related to BLE operations. The binary as of now does not support broadcast or observer mode, you've to code it yourself if required.

CC254x has been around longer and has more people using it. With mbed supporting nrf51822 now I guess you will find more open support for this chip too. And recently Dialog Semiconductor have also announced their seemingly impressive BLE chip, but there is scare info about it being low cost and having good specs.

Hope this helps.

29 Mar 2014

Thanks so much Prithvi.. By the way I did take a look at your blog and you did do a great deal of research. Awesome work.

16 Apr 2014

Hi Simon:

I am new to BLE. nrf51822 is a BLE peripheral role solution. Any chance to work on a BLE with central and peripheral roles such as TI's CC2540?

The reason I ask is that BLE peripheral role device only broadcast and it could not know the other end wants. It can only be connected from one master role device at any time.

Any comment from anyone?

16 Apr 2014

Found this https://devzone.nordicsemi.com/index.php/noob-question-gatt-client. It says that

S110 SD support both a GATT server and client at the same time. So it is possible to have Gatt Client.?

16 Apr 2014

After digging further, I think the post is questionable. From Nordic's website: https://devzone.nordicsemi.com/documentation/nrf51/4.1.0/html/group__nrf518__lib__ble__s110__intro.html, S110 SD only supports peripheral and broadcast roles. It can never a central role. Perhaps they have an internal S110 firmware that support central role.

From my understanding, peripheral is really meant for:

  1. Low power - Remote end need not to connect to it to get data update.
  2. Secure - Remote end could not change its internal stage over the air
  3. One to many connection easily and does not need much memory to implement and keep track of connection status.
16 Apr 2014

HM Yoong: GATT servers and clients are independent of whether a device is a peripheral or central. Briefly, there are four roles:

Central - A device like a phone that can scan for peripherals and start a low-level radio connection to them, e.g. your phone, or a bluetooth dongle. Peripheral - The BLE device that advertises its availability and can receive low-level radio connections, e.g. heart-rate monitor. Broadcaster - Like a peripheral but it only has transmitter hardware so it can only send packets to observers. Observer - Like a central but it only has receiver hardware so it can only receive packets from observers.

The GATT server/client relationship operates on top of the low-level radio connection and can go in either direction. A Central device can run a GATT server and also connect to GATT clients on the peripheral. The same is true in the other direction.

Then the soft devices are:

S110 - Supports Peripheral or Broadcaster (and I believe the latest update can do both simultaneously). S120 - Supports Central or Observer S130 (not available yet) - Supports Central and Peripheral.

25 Sep 2014

I'm happy to do testing. I'm looking to making a GATT client on a mbed that can receive GATT server notificaitons from an Android phone.

Please point me in the right direction.

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