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CY5677 dongle does not connect with peripheral after bonding | Cypress Semiconductor

CY5677 dongle does not connect with peripheral after bonding

Summary: 3 Replies, Latest post by Yiannis on 23 Sep 2016 07:07 AM PDT
Verified Answers: 0
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Yiannis's picture
42 posts


I have a question regarding the CY5677 BLE4.2 dongle.

I use the example BLE4.2 project with the following configuration.
Security mode: 1
Security level: Unauthenticated pairing with encryption
I/O capabilities: No input/no output
Bonding requirement: Bonding
Link Layer Privacy disabled

The CY5677 BLE4.2 dongle is connected with the peripheral (CY8CKIT-143A pluged to the pioneer BLE kit) and it succesfully enables the notifications using the CySmart 1.2.
The problem is when I try to reconnect. In the pairing procedure, the error "Authentication failed. Value information mismatch" is displayed.

Applying the exact scenario using the dongle BLE4.1, this error is not noticed.

Why this error fires? Is perhaps a bug in dongle firmware or CySmart or am I doing something wrong?

Best Regards,

HIMA's picture
Cypress Employee
383 posts

Hello Yiannis,

Can you please tell which project you have programmed, in the pioneer kit.



Yiannis's picture
42 posts

Hello Hima,

Thank you very much for your reply.
The project I loaded in the pioneer kit is the BLE_4.2_DataLength_Security_Privacy project.

Best Regards

Yiannis's picture
42 posts

Hi again,

I would like to come back with another question.
Sorry for all these posts with questions, but I am trying to have a better understanding of the BLE security features.

In our custom application, the configuration "Unauthenticated pairing with encryption" as well as "Bonding" has been selected since no input/no output is available.
The functionality of our custom application has been verified using the dongle CY5677 BLE4.2 and using the previous version of the dongle, that with BLE 4.1.

I monitor the events passed to the application when the connection/pairing/bonding/disconnection procedure takes place.
When I use the dongle with BLE 4.1, after bonding, the encryption keys are not exchanged in future connections. I believe this is correct.
When I use the dongle with BLE 4.2, even if bonding is accomplished successfully, in future connections the encryption keys are always exchanged. I can trace this because the CYBLE_EVT_GAP_KEYINFO_EXCHNGE_CMPLT event fires at every pairing request sent by CySmart software. Is this behavior correct?

I believe that the bond mechanism is used in order the keys to be exchanged once. After bonding, only if bonding info is removed this exchange will happen again. So why using the BLE4.2 dongle the encryption keys are sent at every connection? Am I missing something?

Thank you in advance.

Best Regards,

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