Creating a custom ble service

Question

Hello, 
 I am doing some experiments with 2 pca10001 and the ble_hrs example (with s110, s120). As it works well, I would like to mofify this example to fit my needs. I only need to transfer some booleans, some integers and one or two strings. So I start creating a new custom service based on ble_bas.[ch]. Is it the correct way ?
If it is the correct way, I need to add service (BLE_UUID_BLE_ASSIGN(ble_uuid, BLE_UUID_MY_NEW_SERVICE). The UUIDs of the different services are defined in ble_srv_common.h
What value I can choose for my new custom service ? 
 Thanks, 
 Olivier

Chris Lovett · Accepted Answer

I was able to register total custom service and characteristics using my own custom Guids, but you have to reverse the Guid bytes so they are in big endian. For example, I generated the following service Guid: 
 {227cb85f-855b-4044-9b80-7b8cf0f32854} 
 But then in order to register this guid I do this (notice the order of the bytes is reversed): 
 ble_uuid128_t ble_uuid128 = { 0x54, 0x28, 0xf3, 0xf0, 0x8c, 0x7b, 0x80, 0x9b, 0x44, 0x40, 0x5b, 0x85, 0x5f, 0xb8, 0x7c, 0x22 };
uint8_t ble_custom_type;
ble_uuid_t ble_uuid;

err_code = sd_ble_uuid_vs_add(&ble_uuid128, &ble_custom_type); 
if (err_code != NRF_SUCCESS)
{
 return err_code;
}
 
 Now I can use octets 12 and 13 in the service_add call: 
 // Use our custom registered service type.
ble_uuid.type = ble_custom_type;
blle_uuid.uuid = 0xb85f; // octets 12-13 of 128-bit UUID
p_pws->uuid = 0xb8f5;

// Initialize service structure
p_pws->evt_handler = p_pws_init->evt_handler;
p_pws->conn_handle = BLE_CONN_HANDLE_INVALID;
	
// Add service
err_code = sd_ble_gatts_service_add(BLE_GATTS_SRVC_TYPE_PRIMARY, 
 &ble_uuid, &p_pws->service_handle);
if (err_code != NRF_SUCCESS)
{
 return err_code;
}
 
 Same trick works for any custom characteristics. Now when I pair my device and dump the GATT service on my PC I see the service guid: {227cb85f-855b-4044-9b80-7b8cf0f32854}, so everything works great.

Creating a custom ble service

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