Characteristic Value Read

Question

Hello together, 
 i know, there are similar questions about "Reading Characteristic Value", but i don't get a solution for me. My Problem:
I use nRF51DK with SD130 and the Example Project from the Characteristics Tutorial .
I added 1 service and 2 characteristics with each 5 bytes. 
 
 
 Service: UUID: 0x2800 Handle: 0x000C 
 Char Decl. UUID: 0x2803 Handle: 0x000D 
 Char Value: UUID: 0x0001 Handle:
0x000E Array: 01-02-03-00-00 
 Char2 Decl. UUID: 0x2803 Handle:
0x000F 
 Char2 Value: UUID: 0x0002 Handle:
0x0010 Array: 00-00-00-00-00 
 
 I set the permissions for read and write and i can read out and change the values with my smartphone.
Now i want to do something with this 10(2x5) bytes from the peripheral device. And here is my problem. I need them at different times while running, not only when writing/written, and i dont get it, to read these bytes out. 
 I tried this in the main loop for a simple test to read the value 01-02-03-00-00 of Char1: 
 ble_gatts_value_t * temp;
 memset(&temp, 0, sizeof(ble_gatts_value_t));
 err_code = sd_ble_gatts_value_get(BLE_CONN_HANDLE_INVALID, 0x000E, temp);
 APP_ERROR_CHECK(err_code);
 
 But i only get the err_code 0x00000010. 
 
 I hope u understand what i mean/need.
Perhaps you can help me. Thanks a lot.

FormerMember · Accepted Answer

ble_gatts_value_t is defined the following way: 
 typedef struct
{
 uint16_t len; 
 uint16_t offset; 
 uint8_t *p_value; 
} ble_gatts_value_t;
 
 In your example, in order to make temp contain the value of the attribute after calling sd_ble_gatts_value_get(), p_value in ble_gatts_value_t has to be set to point to a location: 
 uint8_t location_for_my_value;


temp.p_value = &location_for_my_value;
temp.len = number_of_bytes_you_want_to_read;
temp.offset = 0;
err_code = sd_ble_gatts_value_set(BLE_CONN_HANDLE_INVALID, 0x000E, temp);
 
 To make the code more robust, I would recommend you to refer to the reference for the attribute handle value, rather than hard code the handle value. For retrieving the battery level value in the ble_app_hrs example in the SDK, it would be the following: 
 err_code = sd_ble_gatts_value_set(m_conn_handle,m_bas.battery_level_handles.value_handle, temp);

Characteristic Value Read

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