maximum length of data over ble

RE: maximum length of data over ble

Petter Myhre — Tue, 29 Sep 2015 07:49:25 GMT

Our SoftDevices limit the payload of each packet to 20 Bytes. The problem is usually throughput, I'm not sure what your requirements are, but you can read more about throughput here. But it seems you are talking about the actual input to the app, this is just how the app is made I think. You should be able to create some kind of buffer/queue between the user input to the app and the app output to the BLE module?

RE: maximum length of data over ble

mukesh — Mon, 28 Sep 2015 15:13:05 GMT

Thanks for the reply. What i have to achive is, i need to send 1024 bytes over air to nrf51822. But from the app the maximum data i could send at a time is limitted to 20.bytes. I don't know its exact reason . Even in the nrfuart app the maximum length of data i could type is 20 characters

RE: maximum length of data over ble

Petter Myhre — Mon, 28 Sep 2015 14:47:59 GMT

I just want to point out that long write will not increase throughput.

RE: maximum length of data over ble

Petter Myhre — Mon, 28 Sep 2015 14:47:36 GMT

What do you mean by instance? What do you want to achieve? The current implementation of BLE UART gives you the highest throughput possible.

RE: maximum length of data over ble

Michael Dietz — Mon, 28 Sep 2015 09:01:36 GMT

Hey,

One way of doing this is to implement long write. Just search the dev zone for questions on this topic as there are a lot. Follow this github example but repeat the steps for UART service: github.com/.../ble_app_hrs---LongWrite

-It shouldnt be hard to implement this and BLE UART module in nRF toolbox for android will support this.

However in some cases splitting the data into 20 byte packets is better. When doing a long write you will need to declare a buffer to store the read and this takes up a lot of ram. In your case to send 1024 bytes of data you might be looking at 1400 byte buffer because there is also overhead. And then you will need to parse the received buffer to extract your actual data.

-Mike