7 Replies Latest reply on Sep 5, 2017 8:20 AM by risc_1592346

Password Control of Available Characteristics

risc_1592346 Aug 30, 2017 9:28 AM

I am trying to implement password control (via smartphone) of my BLE application. I have a write-only password characteristic and several other custom characteristics.

Initially the characteristics are disabled (except the password characteristic) via:

CyBle_GattsDisableAttribute(xxxx_HANDLE);

Once the correct password is received I enable the other characteristics via:

CyBle_GattsEnableAttribute(xxxx_HANDLE);

Using CySmart I cannot see the newly enabled characteristics appear, either using "discover all attributes" or "read all characteristics". Can I assume they are enabled and usable at this point? Is this a valid way to approach this?

Thanks

Rich

1. Re: Password Control of Available Characteristics

sujayy_46 Sep 1, 2017 5:39 AM (in response to risc_1592346)

Rich,

Yes, after the characteristic is enabled, you can assume it to be usable. Check the return value of the API to ensure that the attribute was indeed enabled.

In CySmart, if you "Discover All Attributes" after the attributes are enabled, then you should be able to see the new characteristics. I tested this with a simple project and it worked fine.
Like Show 1 Likes(1)

Actions
2. Re: Password Control of Available Characteristics

epr_1639216 Sep 1, 2017 8:16 AM (in response to risc_1592346)

As sujayy_46 said, make sure to check the return code to see if there was an error. Most likely you are having trouble with the enable/disable function returning an error.
Like Show 0 Likes(0)

Actions
3. Re: Password Control of Available Characteristics

risc_1592346 Sep 1, 2017 9:17 AM (in response to epr_1639216)

Thank you for the help. After enabling the characteristic "Discover All Attributes" does not show them. If, after enabling them, I write to the characteristic using CyBle_GattsWriteAttributeValue and then use "Discover All Attributes" they show up.
Does this make sense?

Thanks

Rich
Like Show 0 Likes(0)

Actions
4. Re: Password Control of Available Characteristics

epr_1639216 Sep 1, 2017 12:09 PM (in response to risc_1592346)

Does it do the same behavior for the disabling of the attribute as well?
Does reading the attribute after enabling/disabling it cause the same effect?
I can't find much useful documentation on the enable/disable attribute functions...
Like Show 0 Likes(0)

Actions
5. Re: Password Control of Available Characteristics

risc_1592346 Sep 1, 2017 3:05 PM (in response to epr_1639216)

I will have to experiment with the disabling...

I have been fighting what I think is a Cypress bug. I have been changing the characteristics in my custom service and at some point, disabling the characteristics as I was, I was no longer to connect to the peripheral!
If I did not disable it connected fine.

After a lot of debugging I found that if you disable the last characteristic in the list (In the GUI) you cannot connect. Replacing the last characteristic in the list with one that I am not disabling fixed it.

Cypress, care to verify?

Rich
Like Show 0 Likes(0)

Actions
6. Re: Password Control of Available Characteristics

sujayy_46 Sep 3, 2017 10:51 PM (in response to risc_1592346)

Are you sure you are using the latest version of BLE component, i.e v3.30? I have tested these APIs and not found any issue.

Would it possible for you to share your project so that we can test? Might be some corner case which we might have missed or an incorrect implementation.
Like Show 0 Likes(0)

Actions
7. Re: Password Control of Available Characteristics

risc_1592346 Sep 5, 2017 8:20 AM (in response to sujayy_46)

Are you a Cypress employee? I would need a direct Cypress email and would have to verify that a non-disclosure is in place.

Rich
Like Show 0 Likes(0)

Actions

Go to original post