Long characteristics SDK example when read long characteristic value back is limited to 20 bytes

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Anonymous
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Hi

I downloaded WICED smart SDK2.2.1 and built/downloaded long characteristic application example to tag3 board.

When I wrote 26 bytes out to long characteristic value (size of a length of more than 23 bytes. GATT procedures for prepare write and execute write should be used) and then read back the characteristic value, the read result only showed 20 bytes instead of 26 bytes that were written out.

I wonder if there was something the read long characteristics always be limited to 20 bytes in long characteristic application example in SDK, if yes, please advises how to remove this limitation.

I intend to test out a long characteristics value that has size of 255 bytes for read/write/notification and indication.

I used long characteristic application example to try out without any modification and found this limitation.

See below log capture.

=========================================

V 15:52:35.962 Notifications and indications disabled for 361e118a-5524-29b6-0345-b15e12e25b34
V 15:53:07.159 Writing to characteristic 361e118a-5524-29b6-0345-b15e12e25b34
D 15:53:07.178 gatt.writeCharacteristic(361e118a-5524-29b6-0345-b15e12e25b34)
I 15:53:07.202 Data written to 361e118a-5524-29b6-0345-b15e12e25b34, value: (0x) 77-77-65-72-74-79-75-69-6F-70-61-73-64-66-67-68-6A-6B-6C-7A-78-63-76-62-6E-6D
V 15:53:19.488 Reading characteristic 361e118a-5524-29b6-0345-b15e12e25b34
D 15:53:19.500 gatt.readCharacteristic(361e118a-5524-29b6-0345-b15e12e25b34)
I 15:53:19.634 Read Response received from 361e118a-5524-29b6-0345-b15e12e25b34, value: (0x) 77-77-65-72-74-79-75-69-6F-70-61-73-64-66-67-68-6A-6B-6C-7A
=========================================

Please advise.

Thanks!

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1 Solution
2 Replies
MichaelF_56
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I think you will find this discussion helpful: Support for very large characteristics

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Anonymous
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Thanks, the link you post is useful, I succeeded to write and read for 255 bytes size of the characteristic value

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