Max number of LL PDUs / max payload size

[uutzinger]

With MTU 517 and LL tx_octets=251, a notify SDU can span two LL PDUs (SDU capacity ≈ 2×(251−MIC) = 502 bytes). Payload chunk should be ≤ 502 − (L2CAP 4 + ATT 3) = 495 bytes.

However this library implementation seems to limit notifies to one LL PDU (~244–247 payload) as attempts to send ~495-byte chunks trigger application error (EAPP).

[h2zero]

Thanks @uutzinger, I will update the nimble core soon which will hopefully resolve this.