How to get the characteristic data with array?

Question

Hi. 
 I have a customize characteristic that allow user to typing 8 bytes of data send from cell phone, 
 And I want to get this buffer out to go with my process, but I used sd_ble_gatts_value_get() I get the data seems like the register address. 
 Also the ble_gatts_evt_write_t -> data[1] called in on_write function that only stored with 1 bytes. 
 So how can I get the full buffer of data? Is there a example or some tutorial that shows how to do it? 
 Thanks.

Edvin · Accepted Answer

Hello, 
 If you see in the ble_gatts.h file in the SDK on line 353 (in SDK15), it says: 
 uint8_t data[1]; /**< Received data. @note This is a variable length array. The size of 1 indicated is only a placeholder for compilation.
 See @ref sd_ble_evt_get for more information on how to use event structures with variable length array members. */ 
 
 So the data coming at the event is longer than 1 byte. The length of the array is 
 ble_gatts_evt_write_t->len; 
 the 1 is only a placeholder for the compilator. 
 
 You can check out the ble_app_uart example found in SDK\examples\ble_peripheral\ble_app_uart. In main.c, you will see a function called nus_data_handler(...) 
 It is actually a ble_gatts_evt_write_t event, but it is "translated" to a NUS (Nordic UART Service) event in ble_nus.c, in the on_write() function, then calling the nus_data_handler(...) with the translated event. 
 You can see that 
 evt.params.rx_data.p_data = p_evt_write->data; 
 evt.params.rx_data.length = p_evt_write->len; 
 and that these are used in the nus_data_handler(...) in main.c. 
 
 Best regards, 
 Edvin