BLE MTU issue

Question

Marcoasd OP

Created Dec ’17

Replies 2

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Hi all,

I would like to ask about how iOS can negotiate the MTU size with a BLE peripheral.

Compare to Android OS, iOS doesn't have open API to send such a request, but only have API to read the current MTU size.

However, I found that Punch Through's LightBlue iOS App would send MTU request = 185 on connection start randomly (1 out of 4 times) in its previous versions (which is missing on currently available verison).

Do you guys have any idea that can let App and BLE device to negotiate the MTU size?

Or is it possible for me to purposely sent a packet (filled as standard ATT_MTU_Exchange_Req format with Opcode 0x02) to BLE peripheral to "act" like a MTU Exchange process?

Thanks

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Answer 1

jmb2k6 OP

Dec ’17

The MTU is negotiated during connection process. iOS will automatically use the largest value supported by both devices. iOS supports up to 185 so that is the max value that will be supported. If the peripheral device supports and MTU of less than 185, then that value will be used. There is no open iOS API to request an MTU change/update. Instead, this request would need to be initiated by the peripheral.

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Answer 2

jmb2k6 OP

Dec ’17

an*

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