How to setup data / data layout for transmitting time series?

[Adib]

Hello All,

my application should record acceleration data and time stamps.

After recording the data block from start to end should be transmitted.

I only know that BLE transmits the as is (current) data.

How can I request a timestamped data?

How to efficiently transmit the data without application specific acknowledge after each data set?

I think this topic is addressed by weather station or activity monitor apps.

But I can't find how.

Thanks for any hints.

Adib.

--

[ovrebekk]

Hi Adib

Are you using a mobile phone on the central side?

If so you can set up the phone to host the BLE Current Time Service (CTS), and use it to provide accurate time information to the connected BLE peripheral. Then you need to keep track of time locally on the nRF52 side by running the RTC timer, and keeping track of how many seconds has passed since the last time the phone sent the current time information. 

In order to keep somewhat accurate time on the nRF52 in between phone sync you should consider using an external LF crystal. This is not needed for most Bluetooth applications, but makes a difference if you need to keep track of time over days or more. 

Once you have a relatively accurate clock running locally you can embed a timestamp to your sensor data and send it back to the phone. 

Best regards
Torbjørn