Data size limitation

[pavan]

Hello All,

I am working nrf51DK and i am using ble_app_uart application with s130 softdevice. Now my query is I am trying to send some data from my mobile application to ble chip(nrf51dk) but when i send more than 20bytes the dk get resets. so is there any limitation on data packet size , if yes how to increase the same?

please advice

thanks in advance pavan

[endnode]

There are certain limitations in the examples but BLE as such as well as Nordic BLE UART Service don't have any limitations which you couldn't overcome. If your chip resets itself then you probably encounter some hard fault or asserted error return from SD API. Please debug your FW, find the line in your code which invokes this assert and fix it.

[pavan]

Hi , Thanks for your information.

So you mean to say we can send more than 20bytes of data rite?

[endnode]

I mean you can send how many 20-byte packets you want and they should arrive to the other side sooner or later in the same order. There is limit of how many Tx packets can be waiting on GATT layer in the queue so if you want to achieve maximum throughput with given PDU and ATT_MTU lengths you need to have also some application buffer(s) to have all these packets ready once SD API allows you to put there more.

[pavan]

No actually i want to send more than 20bytes in a packet and If i tried to do so(sending around 30 bytes) BLE getting disconnected from the connected device.

[endnode]

On GATT and LL layers you need to respect the limitations. On higher layers (APP - that's where you should design your things!) you are free to do some fragmentation/reassembly layer. Bluetooth isn't asynchronous wire where you can just start streaming and never stop, it's based on strict timing and as such certain layers have packet limitations. Deal with it or go with different technology.

[pavan]

Hello Sir,

Thanks for the information.

I have requirement of send 255bytes of over BLE and then in turn i need send that received 255 bytes of data via UART to ECU.

Now i am ok with sending split data i.e packet of 20 bytes of data sequentially. but now my query is my ECU will response only when it receives 255 bytes of data. so please advise on how and where to store the received split data of 255 bytes ans send full 255bytes of data via UART?

is there any code for such application?

thanks in advance