Data Length Extension using BCM20737?

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PhRi_4317641
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First question asked First reply posted

Is there any way to increase MTU size using the data length extension seen in BLE 4.2 and above? What BLE version is the BCM20737 compatible? I also heard that it is possible to increase BLE throughput if the GATT profile uses HID? Can this be done in WICED smart IDE? If so, how do I do this?

Thank you for your time.

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AnjanaM_61
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5 comments on KBA First comment on KBA 5 questions asked

Hello,

20737 BLE stack is compatible with Bluetooth 4.1. DLE is 4.2 feature, thus not supported in 20737.

Default MTU size supported in WICED SMART is 23 bytes.

You can increase the MTU from 23 till 512 (as per spec), below are the examples for reference:

- long_char_big_mtu ( /WICED-Smart-SDK/Apps/long_char_big_mtu )

- puart_control_big_mtu ( /WICED-Smart-SDK/Apps/puart_control_big_mtu  )

For speed test, you may refer to the sample app speed_test in WICED SMART SDK ( /WICED-Smart-SDK/Apps/speed_test )

Thanks,
Anjana

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AnjanaM_61
Moderator
Moderator
Moderator
5 comments on KBA First comment on KBA 5 questions asked

Hello,

20737 BLE stack is compatible with Bluetooth 4.1. DLE is 4.2 feature, thus not supported in 20737.

Default MTU size supported in WICED SMART is 23 bytes.

You can increase the MTU from 23 till 512 (as per spec), below are the examples for reference:

- long_char_big_mtu ( /WICED-Smart-SDK/Apps/long_char_big_mtu )

- puart_control_big_mtu ( /WICED-Smart-SDK/Apps/puart_control_big_mtu  )

For speed test, you may refer to the sample app speed_test in WICED SMART SDK ( /WICED-Smart-SDK/Apps/speed_test )

Thanks,
Anjana

Thanks so much for the response. Does the speed_test application give me the maximum throughput possible from the BCM20737? It seems like this application uses 20 Byte MTU, so shouldn't we see a larger MTU size in an application like this? I also notice that the GATT characteristic does not use HID over GATT. Doesn't HID increase throughput? Also do you know how to setup HID over GATT?

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Hi,

speed_test won't be able to give max through put. However you mat refer that to try throughput example along with increasing MTU with help of the examples, - long_char_big_mtu and puart_control_big_mtu .

Q) Doesn't HID increase throughput?

A) I think this will be applicable if peer device is iOS. Because iOS will allow low connection interval for HID profile and hence more throughput as described here: https://punchthrough.com/maximizing-ble-throughput-on-ios-and-android/

Q) Regarding HID support, please refer the below threads:

Re: Reg: HID Library for BCM20736

Re: BCM20737 - HID Keyboard

Thanks,
Anjana

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