GAP central and GATT server

[spike]

Hi:

I'm implementing an controller for an open source drone Crazyflie (www.bitcraze.se/.../). My device is similar to pca10001 board. Since Crazyflie is acting as peripheral, I make my device act as GAP central (S120 1.0.0 and SDK6.1). What's more, I need to make my device act as GATT server so I can send control command to the Crazyflie. I try to find example from SDK for a central and GATT server combination but could not get one. So I change the code upon ble_app_multilink_central example. After some adaption, the GAP connection and service discovery is OK. However, when I want to send command via sd_ble_gatts_hvx(), it will return BLE_ERROR_GATTS_SYS_ATTR_MISSING. I already add the gatts characteristic, but I notice that this Crazyflie peripheral will not send notification to my device. I'm not sure if that''s the problem. I want to know if there is any example for "GAP central and GATT server" so I can refer to?

I also attached my code and running log. Appreciate it if someone can look at it and help me! Thanks! ble_app_multilink_central.rar

[Petter Myhre]

Are you sure the Crazyflie is running a GATT client? What services/characteristics is it looking for on the GATT server? Do you have a spec or something you could share? I tried to have a look at your code, but it is difficult without your complete project.