How to get simultaneous data streaming between two devices using one BLE connection

RE: How to get simultaneous data streaming between two devices using one BLE connection

Anders Strand — Thu, 10 Dec 2015 08:54:55 GMT

Are you using the nRF51 DK? Check the Keil settings under Target options -> Debug ->Settings. Also try searching devzone for the error. There are probably 100 posts about this.

RE: How to get simultaneous data streaming between two devices using one BLE connection

CWRUNick — Wed, 09 Dec 2015 17:54:26 GMT

Thanks, Anders! So I am trying to use the ble_app_uart example from your SDK using Softdevice S110, but I'm having some trouble getting started. I am using Keil, and I haven't been able to run any examples because I keep getting the error message "No JLink Devices found" followed by "Error: Flash Download failed - Target DLL has been cancelled." I went to Segger.com and downloaded JLink software but I still get this error. Do you know how to resolve this?

RE: How to get simultaneous data streaming between two devices using one BLE connection

Anders Strand — Wed, 28 Oct 2015 09:54:06 GMT

Hey!

@Shibshab is correct about the GATT operations. Use Notifications on the peripheral and write commands on the central.

When using mBed, the S130 Softdevice is used. This softdevice support concurrent central/peripheral operation, but has a smaller output buffer for each link. This results in the maximum packet per connection interval being 2. If you want to get maximum troughput, you can use the ble_app_uart example from our SDK, and use Softdevice S110. This gives you 6 packets each connection interval.

Alternatively, you can export your mBed project to Keil, and manually flash the S110 softdevice. This will require a bit of tweaking of various parameters both in code and compiler settings. Let me know if you go for this solution, and i will help you out.

-Anders

RE: How to get simultaneous data streaming between two devices using one BLE connection

shibshab — Tue, 27 Oct 2015 18:24:03 GMT

What ATT operation are you using? (I.E. read request/write request). In cases where high throughput and low latency is required, the Write Command and Notification ATT commands should be considered as they are asynchronous and does not require ATT layer acknowledgement, which allows for multiple data transfers to occur on each connection event.