Max BLE Characteristic write size with long write APIhttps://devzone.nordicsemi.com/f/nordic-q-a/68510/max-ble-characteristic-write-size-with-long-write-apiHello, We are looking to send around 1000 Bytes on characteristic. On android app we used Nordic apis to send long write for sending 1000 byes but I am receiving only 509 bytes only once. Not sure if I am doing something wrong on Nordic firmware sideen-USTelligent Community 13Mon, 23 Nov 2020 09:03:22 GMTRE: Max BLE Characteristic write size with long write APIhttps://devzone.nordicsemi.com/thread/281252?ContentTypeID=1Mon, 23 Nov 2020 09:03:22 GMT137ad170-7792-4731-bb38-c0d22fbe4515:587b4173-92f8-4abb-b6a3-d75f9ce1bd5aVidar Berg<p>The attribute value length can be set independent of the ATT_MTU size. E.g. an attribute can still hold 512 bytes even if only the default 23 byte&nbsp; MTU is supported.You are however limited to &quot;ATT_MTU - 3&quot; bytes when sending notifications.</p> <p>The 3 byte ATT packet overhead consists of one byte for the attribute opcode and 2 bytes for the attribute handle.</p><div style="clear:both;"></div>RE: Max BLE Characteristic write size with long write APIhttps://devzone.nordicsemi.com/thread/280963?ContentTypeID=1Thu, 19 Nov 2020 16:26:38 GMT137ad170-7792-4731-bb38-c0d22fbe4515:d515af71-159a-4545-82fd-50c1f4431351chandan<p><span>Max length include a 3 byte overhead, so the actual useable data that can be notified is ATT_MTU - 3 bytes so max possible is 509, correct ?</span></p> <p><span>Also please me know what is these 3 bytes overhead?</span></p><div style="clear:both;"></div>RE: Max BLE Characteristic write size with long write APIhttps://devzone.nordicsemi.com/thread/280957?ContentTypeID=1Thu, 19 Nov 2020 15:58:32 GMT137ad170-7792-4731-bb38-c0d22fbe4515:7dae7000-8791-49e9-90e5-e0e0fabc1921Vidar Berg<p>Hello,</p> <p>The maxium length of an attribute value is 512 bytes according to the Bluetooth spec., so 1000 bytes is not possible, unfortunately.</p><div style="clear:both;"></div>