DIS Update Serial Number

RE: DIS Update Serial Number

Einar Thorsrud — Mon, 10 Dec 2018 10:30:40 GMT

Hi,

There is essentially two things you need to think of:

The initial length becomes the maximum length.
The maximum length is always used unless you set is_var_len in the characteristics properties to true (I did not mention this in my initial post).

With those things in mind updating the serial number works when I tested on my side. You can see these modifications from SDK 15.2 where I used your code and the HRS example. Button 4 on the DK is used to update to a new and shorter serial number.

devzone.nordicsemi.com/.../main.c.diff

devzone.nordicsemi.com/.../ble_5F00_dis.c.diff

RE: DIS Update Serial Number

oneguy — Fri, 07 Dec 2018 15:29:15 GMT

Hi Einar,

With respect to persistency: yes, of course...

With respect to what doesn't work: The text displayed on nRF Connect (for example) is different to the string I'm passing to sd_ble_gatts_value_set. Do I need to pad out my string with \0 to max_len?

Example:

assume max_len is set to 16
I set serial_number to "1232" -> what do I need to do?
I update serial number to "aaddbbtt" -> what do I need to do?
I update serial number to "?" -> what do I need to do?

I would like nRF Connect to display exactly what is shown in the example.

Cheers

RE: DIS Update Serial Number

Einar Thorsrud — Fri, 07 Dec 2018 11:59:16 GMT

Hi,

The length you are using during initialization becomes the maximum length for each characteristic, so using the maximum length for ble_dis_init_t::serial_num_str.length in the call to ble_dis_init() should be all you need to do. In what way does it not work?

As a side note: If you want the serial number to be persistent so that the new serial number is used after reset, you have to write it to flash (for instance using FDS) and read it and set it accordingly when you call ble_dis_init() after reset.