# Change MTU BLE Server

**URL:** <https://forum.amebaiot.com/t/change-mtu-ble-server/3376>\
**Category:** BT\
**Tags:** rtl8735b\
**Created:** [September 29, 2024, 9:00pm UTC](https://forum.amebaiot.com/t/change-mtu-ble-server/3376 "2024-09-29T21:00:43Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Ivan](https://avatars.discourse-cdn.com/v4/letter/i/df788c/32.png) [@Ivan](https://forum.amebaiot.com/u/Ivan)\
**Post date:** [September 29, 2024, 9:00pm UTC](https://forum.amebaiot.com/t/change-mtu-ble-server/3376/1 "2024-09-29T21:00:43Z")

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Hi, how can i change the MTU in a BLE server application?  
How can i read the actual value of the MTU?  
Thanks

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**Author:** ![Ivan](https://avatars.discourse-cdn.com/v4/letter/i/df788c/32.png) [@Ivan](https://forum.amebaiot.com/u/Ivan)\
**Post date:** [October 1, 2024, 8:31am UTC](https://forum.amebaiot.com/t/change-mtu-ble-server/3376/2 "2024-10-01T08:31:03Z")

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I changed the definition in “BLERemoteCharacteristic.h” and “BLECharacteristic.h”

from  
#define CHAR\_VALUE\_MAX\_LEN 230

to #define CHAR\_VALUE\_MAX\_LEN 1024

and now i’m able to receive 512 byte max, is this an hardware limit or can i increase it with other setup?

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**Author:** ![KevinKL](https://sea2.discourse-cdn.com/flex016/user_avatar/forum.amebaiot.com/kevinkl/32/2632_2.png) [@KevinKL](https://forum.amebaiot.com/u/KevinKL)\
**Post date:** [October 2, 2024, 5:50am UTC](https://forum.amebaiot.com/t/change-mtu-ble-server/3376/3 "2024-10-02T05:50:31Z")

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Hi @Ivan ,

The maximum length of a BLE attribute value is 512 bytes, as stated in [Core Specification | Bluetooth® Technology Website](https://www.bluetooth.com/specifications/specs/core-specification-6-0/) (pg.1485).

Thank you.