PRIMARY_SERVICE, GAP_SERVICE
CHARACTERISTIC, GAP_DEVICE_NAME, READ, "BTstack"
CHARACTERISTIC, GAP_APPEARANCE, READ, 00 00

PRIMARY_SERVICE, GATT_SERVICE
CHARACTERISTIC, GATT_SERVICE_CHANGED, READ,

PRIMARY_SERVICE, FFF0
CHARACTERISTIC, FFF1, READ | WRITE | AUTHENTICATED_SIGNED_WRITE | AUTHENTICATION_REQUIRED, "A"