mesh gatt and ble gatt

[Blastka]

Hi. I have read the documentation and I have a couple of questions:

1. What makes work different mesh_gatt and nrf_ble_gatt? Why can't they work together (maybe it's because of ATT_MTU, but I'm not sure).
2. Why can I write and read a characteristic without function gatt_init in nrf5 sdk?
3. how the characteristics created as in the BLE project in mesh will work? i created service and characteristics. they will communicate through the mesh gatt?

[Hung Bui]

Hi Blastka, 

1. Yes they can work together. In our co-exist example we don't have GATT Proxy implemented but it's possible to add that in. Please have a look at my example here: https://devzone.nordicsemi.com/f/nordic-q-a/53837/including-nrf5-sdk-for-mesh-functionality-in-an-nrf5-sdk-example/235538#235538

2. Could you explain more ? gatt_init () function initialize the nrf_ble_gatt module. It's not directly related to read/write characteristics

3. Mesh Gatt is only handling the Mesh GATT proxy/provisionining service. So it doesn't handle any other service. You handle your service as usual. 

[Blastka]

1. yes, but in your coexistence example gatt_init is commented out. In my example, gatt and mesh gatt do not work together.

2. Why? gatt is responsible for communicating characteristics and services. 

3. another question. I activated pb-gatt and proxy in config, but did not initialize. I use gatt_init. my treatments go to mesh_gatt_on_ble_evt and call hardfault. 
static mesh_gatt_t m_gatt;
NRF_SDH_BLE_OBSERVER (m_gatt_obs, NRF_MESH_GATT_BLE_OBSERVER_PRIO, mesh_gatt_on_ble_evt, & m_gatt);
#endif

[Hung Bui]

1. It's commented out because the mesh_gatt.c already handle the ATT_MTU request. 

2. Again the gatt_init() is only initialize the nrf_ble_gatt module which handles the ATT_MTU and the Data lenght request. It's not related to the service and characteristics.

3. Please send what inside your "gatt_init" maybe it's different from my gatt_init. Please follow what I did in the example that I quoted. Note the change in  nrf_mesh_provisionee.c 

[Blastka]

3.  This is my project. The project has no uart.

NRF_BLE_GATT_DEF(my_m_gatt);

/**@brief Function for initializing the GATT module.
*/
void gatt_init(void)
{

ret_code_t err_code = nrf_ble_gatt_init(&my_m_gatt, NULL);
APP_ERROR_CHECK(err_code);

err_code = nrf_ble_gatt_att_mtu_periph_set(&my_m_gatt, NRF_SDH_BLE_GATT_MAX_MTU_SIZE);
APP_ERROR_CHECK(err_code);
}

Because of observers it works so incorrectly. NRF_BLE_GATT_DEF(my_m_gatt);      and 
NRF_SDH_BLE_OBSERVER (m_gatt_obs, NRF_MESH_GATT_BLE_OBSERVER_PRIO, mesh_gatt_on_ble_evt, & m_gatt);
Why are they processed together. nrf_ble_gatt_on_ble_evt and mesh_gatt_on_ble_evt.

[Hung Bui]

As I mentioned the gatt_init() initialize nrf_ble_gatt () which handle the ATT_MTU update and Data length update. This is already handled by mesh_gatt so you don't need that module.

Please remove the nrf_ble_gatt.h and nrf_ble_gatt.c from your project. 

It has no direct impact to GATT services and characteristics. 

[Blastka]

I deleted, now my program hangs in this place when disconnecting from the phone, when i run  advertising without mesh:
.thumb_func
.weak HardFault_Handler
HardFault_Handler:
b .

[Hung Bui]

Hi, 
Hardfault is not a deadend, please try to debug and find where it crashed. Have a look here: https://devzone.nordicsemi.com/f/nordic-q-a/12291/what-can-cause-a-hardfault-and-how-to-catch-it

Please try to check and compare your code to the coexist example or my example that I pointed to earlier.