CC2564C: Does the CC2564C chip allow an MTU size larger than the standard size when connecting via BLE

Brad Caldwell

Part Number: CC2564C

Does the CC2564C chip allow an MTU size larger than the standard size when connecting via BLE? We are working on a new device that will connect to one of our tablet devices employing the TI CC2564C chip. The new device is BLE only and we would prefer to transmit using a larger MTU size. We looked at the data sheet and they tell us a larger MTU is available for standard Bluetooth but it is not clear if an MTU larger than 23 bytes is available when using a BLE connection

Thanks

over 3 years ago

0 Jacob B. over 3 years ago

TI__Genius 13052 points

Hi Brad,

The CC2564C using the Bluetopia stack has a max ATT MTU size of 517 bytes, which should be sufficient. However, the MTU size is often dictated by the L2CAP connection established between the two devices. The negotiated MTU size could be lower if the tablet has a smaller MTU size.

Thanks,
Jacob

0 Newman over 3 years ago

TI__Expert 6005 points

Hi Jacob,

Thx.. this inquiry is specifically for BLE and how to use a larger MTU size w/ BLE. How large of a BLE MTU is allowed for each of the devices CC2564A/B/C (and their associated SDK/stacks)? How do I increase the size of the BLE MTU in the SDK?

Thanks, Merril

0 Jacob B. over 3 years ago in reply to Newman

TI__Genius 13052 points

Hi Merril,

I'll have to get back to you on this question later this week.

Best,
Jacob

0 Jacob B. over 3 years ago in reply to Jacob B.

TI__Genius 13052 points

Hi Merril,

Apologies, but I will need to follow up here next week.

Best,

Jacob

+1 Jacob B. over 3 years ago in reply to Jacob B.

TI__Genius 13052 points

Hi Merril,

After reaching out to an expert, I can confirm the ATT MTU size on our CC256x controllers have a max of 27 octets (bytes). Our devices do not support the LE Data Packet Length Extension feature, meaning that negotiated MTU size is fragmented at the baseband into 27-octet frames. This is true even if the L2CAP or ATT MTU size is increased in the stack.

Best regards,
Jacob

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CC2564C: Does the CC2564C chip allow an MTU size larger than the standard size when connecting via BLE