Basic STM32WB Notification question?

[SWenn.1]

Good morning.

I am using a NUCLEO-WB55 board and nRF Connect to prototype a design.  I am trying to understand notifications. Using the attached picture I am hoping someone can answer my question.  The characteristic a1725a01.... has read, notification and indication properties on it.  I have enabled notifications.  Characteristic a1725a02 has read and write properties on it.  Both characteristics (a01 and a02) read the same variable.  If I write to characteristic a02 and then read characteristic a02 I get what I wrote (as one would expect).  The question I have is:

With a01 notifications enabled should I expect that a01 automatically updates with the value (recall a01 and a02 point to the same variable) or do I have to intentionally read a01 to get the value to update?

 

Thank you.

 

[DS.4]

I believe that if you want that kind of behavior do :

 

automatically:

1. NRF: Write data X to a0, read it if you want, you are allowed.

2. ST:  Event:  a0 written with data X. (believe st has this event in most of its examples )

3. ST: Write ( "Pass" ) the data X to a1 with a method that sends a notification. ( your added logic)

4. NRF: Notification of data X on a1. ( "automatically" )

 

manually: (changing steps  (3), (4) ) 

3. ST: Write ( "Pass" ) the data X to a1 with a method that doesn't send a notification.

4. NRF: Read data X out of a1. (manually)

 

 

[SWenn.1]

DS.4

thanks for the reply...new to this at this end so I am struggling thru things.

I have W/R/Notifications on one characteristic (Stevenotify) at this end now.

The CubeMX automagically creates custom_app.c and places two functions within it:

1. void Custom_Stevenotify_Update_Char(void)

2. void Custom_Stevenotify_Send_Notification(void)

both functions call the same function with the same opcode but a different payload

Custom_STM_App_Update_Char

This function does nothing more than aci_gatt_update_char_value

Given that the opcode is the same I do not understand what the value of the 2 initial functions do other than update the same value.  Can you explain?

I only call function 2 above and it seems to work.  I am not sure the value of 1.

[DS.4]

if I remember correctly they are not the same,

as aci_gatt_update_char_value gets different input parameterts.

 

Something like : 

aci_gatt_update_char_value( WITH_NOTIFICACTION) - this is what I prev called "automatically", you don't have to manually read it using NFC app, the app will receive data "automatically". (event-driven) as the update of the char. also sends the data.

 

aci_gatt_update_char_value( ONLY_UPDATE_CHARACT_DATA_NO_NOTIFICATION) - this is what I prev called "manually" ( polling) . You update char. without sending, then you go to your NFC app and press read ("manually"), and only then you get the data.

 

hope it helps

[SWenn.1]

No....There is absolutely no difference in the call between the two.  Both functions (1 & 2 above) call the same function aci_gatt_.....and the function does not have any parameters to indicate notification or no notification.

I have found that MANY times when I put a break point at this function that the payload, which the debugger shows as correct, never gets transferred to my phone on when I do a read.  Is there some low level functions that could be getting called WITHOUT going thru this aci_gatt_.....call that may be overwriting my payload and sending the wrong data to the phone?

[DS.4]

Try this one:  aci_gatt_update_char_value_ext , it lets you better control what is being done via parameters