S130 long characteristic values

[wizath]

Hi,

I'm facing a little problem with custom service characteristic. I've set char settings as follows

attr_char_value.init_len     = sizeof(uint8_t);
attr_char_value.init_offs    = 0;
attr_char_value.max_len      = 5;
attr_char_value.p_value      = NULL;

When I try to write the characteristic through NRF Connect app, it seems fine. But when I try to update characteristic value with this code:

gatts_value.len	= len;
gatts_value.offset = 0;
gatts_value.p_value = data;  // pointer to data array

err_code = sd_ble_gatts_value_set(p_ctrl->conn_handle,
								  p_ctrl->config_char_handles.value_handle,
								  &gatts_value);

Code executes without errors, but the value read from characteristic don't change. Any ideas what is wrong?

[Petter Myhre]

Strange. What are the values of len and data?

[wizath]

len is simple uint8 value and data is uint8_t *. i'm checking it with logging and everything is fine.

[Petter Myhre]

It should work. As long as you don't use a len larger than 5. Are you checking the returned error code of sd_ble_gatts_value_set()? Is it 0x00000000 (NRF_SUCCESS)?

[wizath]

The main problem was BLE_GATTS_VLOC_USER setting. When changed to BLE_GATTS_VLOC_STACK everything works fine.

[Petter Myhre]

I see.

When you use BLE_GATTS_VLOC_USER the attribute Value is located in user memory. This requires you to maintain a valid buffer through the lifetime of the attribute, since the stack will read and write directly to the memory using the pointer provided in the APIs.