RE: sending lots of data from peripheral to central, queued writes

Eliot Stock — Wed, 24 Jan 2018 14:07:27 GMT

Thanks very much, I'll give this a go. It's roughly what I had before, but the throughput example is a great help. Still confused as to what problem the queued writes module really solves, but no matter. Accepting this for now.

RE: sending lots of data from peripheral to central, queued writes

MartinBL — Fri, 19 Jan 2018 11:27:05 GMT

Hi,

Why not use a sequence of notifications? That is usually how it is done when all you want is to quickly transfer a lot of data without application layer acknowledgment from the peer device. So:

Make a state machine that repeatedly calls sd_ble_gatts_hvx() with your log data until the function returns NRF_ERROR_RESOURCES indicating that the notification queue is full.
Wait for BLE_GATTS_EVT_HVN_TX_COMPLETE events and then continue with sd_ble_gatts_hvx().
All the while you keep incrementing the offset within the attribute value to send new chunks of data until you have sent your entire log.

This is the way data is transferred in the throughput example.