Variable length not working?

[KPE]

/**@brief Attribute metadata. */
typedef struct
{
  ble_gap_conn_sec_mode_t read_perm;       /**< Read permissions. */
  ble_gap_conn_sec_mode_t write_perm;      /**< Write permissions. */
  uint8_t                 vlen       :1;   /**< Variable length attribute. */
  uint8_t                 vloc       :2;   /**< Value location, see @ref BLE_GATTS_VLOCS.*/
  uint8_t                 rd_auth    :1;   /**< Read Authorization and value will be requested from the application on every read operation. */ 
  uint8_t                 wr_auth    :1;   /**< Write Authorization will be requested from the application on every Write Request operation (but not Write Command). */
} ble_gatts_attr_md_t;

Whenever I set .vlen to true the softdevice fails with error 7 on the call to: sd_ble_gatts_characteristic_add

Is this functionality implemented, and are there any examples using it?

[Hung Bui]

Hi KPE,

The variable length attribute is implemented. You can find examples in ble_app_hrm, or ble_app_uart (in PCA10001 folder) projects.

Could you send the characteristic init code that caused error 7 ?

[KPE]

This is what is going into to the metadata struct (the null pointers are not expanded). Do I need to fill in all the structs, or can I just fill in the ones that I don't want to be default?

_ns	0x200031c8	
	char_props	{...}	
		broadcast	0	
		read	0	
		write_wo_resp	0	
		write	1	
		notify	0	
		indicate	0	
		auth_signed_wr	0	
	char_ext_props	{...}	
		reliable_wr	0	
		wr_aux	0	
	p_char_user_desc	0x00000000	
	char_user_desc_max_size	0	
	char_user_desc_size	0	
	p_char_pf	0x00000000	
	p_user_desc_md	0x20003210	
		read_perm	{...}	
			sm	1	
			lv	1	
		write_perm	{...}	
			sm	1	
			lv	1	
		vlen	1	
		vloc	0	
		rd_auth	0	
		wr_auth	0	
	p_cccd_md	0x00000000	
	p_sccd_md	0x00000000	

[KPE]

And the gatts struct... (doesn't work with init_len = 0 either)

ECble::NordicStruct<ble_gatts_attr_t>	{...}	
	_ns	0x20003198	
		p_uuid	0x00000000	
		p_attr_md	0x00000000	
		init_len	20	
		init_offs	0	
		max_len	20	
		p_value	0x20003144	
			*p_value	0	

[Carles]

Hi there,

I am not sure I understand the memory dump you pasted, but here's a possible cause:

If your p_user_desc_md is != NULL and your p_user_desc_md->write_perm allows the user description descriptor to be written to, then you need to set your wr_aux bit in extended properties.

Carles

[KPE]

I've looked at the hrm example, and I think I've spotted the problem. I'm setting the UserDescriptor metadata which is most likely the wrong place.