espressif
Documentation GATT Service Bin
The documentation on how to create a GATT Service CSV is not really accurate and assumes automatisms that are not defined in the standard.
In the first step it should be explained that GATT structures always consist of services, declarations and optional descriptors.
Thus, for example, the first entry should always be a primary service (UUID 0x2800) which determines with its value which service is described (for example, a predefined one such as 0x180A or a self generated one).
Services always consist of Characteristic Declarations which have as UUID 0x2803 and the Value describes which read and write rights are available. The standard describes that the other bytes define the Value Handle and Characteristic UUID, but should not be appended to this CSV (why?).
As a further entry follows the actual attribute. The value of the attribute contains the value which can be written or read by a foreign device. It is important that the Characteristic Declaration authorizations for the read/write authorizations of this attribute match.
The attribute can be described further by descriptors. A special one is the descriptor "Client Characteristic Configuration" (UUID 0x2902) which should be present if the Notify bit has been activated in the Characteristic Declaration (UUID 0x2803). This descriptor should then always be writable and readable.
I'm struggling to add custom GATT service partition. Current documentation mentions three steps:
- define the service in xls or csv file
- use BLEService.py to generate
- download generated bin to address defined in partition table
but only steps 1 and 2 are further described. How to do the third one?
- What is the
address defined in partition table? Is itat_customizedefined in partitions_at.csv? I think not, because from what I can see it loads partitions defined in at_customize.csv. - Should I add another partition? If yes then in which file (at_cusotmize.csv, partitions_at.csv)?
- Should I just append it into partition table and then it gets automagically detected? If yes, how much should I increment partition offset? Some 8k partitions are using 0x2000 increment, whereas some others use 0x1000.
Also, I think it would be helpful to have GATT service example for BLE SPP mode, because creating GATT partitions is needed in "UART-BLE Passthrough Mode" example chapter in documentation.
What is the
address defined in partition table? Is itat_customizedefined in partitions_at.csv? I think not, because from what I can see it loads partitions defined in at_customize.csv.
When you build this project there will be a lot of *.bin files generated and one *.bin files is the ble_data.bin. You should find it in build/customized_partitions. This file has to be written in flash on the correct offset. But when you do make print_flash_cmd should see how and where you have to write this file. The offset is technically that offset which you configure int the at_customize.csv.
Also, I think it would be helpful to have GATT service example for BLE SPP mode, because creating GATT partitions is needed in "UART-BLE Passthrough Mode" example chapter in documentation.
It seems like the example.csv is the nessercary GATT Configuration for using the BLE SPP Feature because the listed Characteristic Declarations in the Manual in the chapter 9.5.2.2 are the same. But I'm also not sure.