Generic Attribute Profile (gatt)#

The commands and events in this class can be used to browse and manage attributes in a remote GATT server.

gatt commands#

gatt_discover_characteristics#

This command can be used to discover all characteristics of the defined GATT service from a remote GATT database. This command generates a unique gatt_characteristic event for every discovered characteristic. Received gatt_procedure_completed event indicates that this GATT procedure has succesfully completed or failed with error.

Command#

This value is normally received from the gatt_service event.

Response#

• 0: success

• Non-zero: an error occurred

For other values refer to the Error codes

API#

/* Function */  
struct gecko_msg_gatt_discover_characteristics_rsp_t *gecko_cmd_gatt_discover_characteristics(uint8 connection, uint32 service);  
  
/* Response id */  
gecko_rsp_gatt_discover_characteristics_id  
  
/* Response structure */  
struct gecko_msg_gatt_discover_characteristics_rsp_t  
{  
  uint16 result  
}  

Events generated#

gatt_discover_characteristics_by_uuid#

This command can be used to discover all the characteristics of the specified GATT service in a remote GATT database having the specified UUID. This command generates a unique gatt_characteristic event for every discovered characteristic having the specified UUID. Received gatt_procedure_completed event indicates that this GATT procedure has successfully completed or failed with error.

Command#

This value is normally received from the gatt_service event.

9 | uint8array | uuid | Characteristic UUID

Response#

• 0: success

• Non-zero: an error occurred

For other values refer to the Error codes

API#

/* Function */  
struct gecko_msg_gatt_discover_characteristics_by_uuid_rsp_t *gecko_cmd_gatt_discover_characteristics_by_uuid(uint8 connection, uint32 service, uint8 uuid_len, const uint8 *uuid_data);  
  
/* Response id */  
gecko_rsp_gatt_discover_characteristics_by_uuid_id  
  
/* Response structure */  
struct gecko_msg_gatt_discover_characteristics_by_uuid_rsp_t  
{  
  uint16 result  
}  

Events generated#

gatt_discover_descriptors#

This command can be used to discover all the descriptors of the specified remote GATT characteristics in a remote GATT database. This command generates a unique gatt_descriptor event for every discovered descriptor. Received gatt_procedure_completed event indicates that this GATT procedure has succesfully completed or failed with error.

Command#

This value is normally received from the gatt_characteristic event.

Response#

• 0: success

• Non-zero: an error occurred

For other values refer to the Error codes

API#

/* Function */  
struct gecko_msg_gatt_discover_descriptors_rsp_t *gecko_cmd_gatt_discover_descriptors(uint8 connection, uint16 characteristic);  
  
/* Response id */  
gecko_rsp_gatt_discover_descriptors_id  
  
/* Response structure */  
struct gecko_msg_gatt_discover_descriptors_rsp_t  
{  
  uint16 result  
}  

Events generated#

gatt_discover_primary_services#

This command can be used to discover all the primary services of a remote GATT database. This command generates a unique gatt_service event for every discovered primary service. Received gatt_procedure_completed event indicates that this GATT procedure has successfully completed or failed with error.

Command#

Response#

• 0: success

• Non-zero: an error occurred

For other values refer to the Error codes

API#

/* Function */  
struct gecko_msg_gatt_discover_primary_services_rsp_t *gecko_cmd_gatt_discover_primary_services(uint8 connection);  
  
/* Response id */  
gecko_rsp_gatt_discover_primary_services_id  
  
/* Response structure */  
struct gecko_msg_gatt_discover_primary_services_rsp_t  
{  
  uint16 result  
}  

Events generated#

gatt_discover_primary_services_by_uuid#

This command can be used to discover primary services with the specified UUID in a remote GATT database. This command generates unique gatt_service event for every discovered primary service. Received gatt_procedure_completed event indicates that this GATT procedure has succesfully completed or failed with error.

Command#

Response#

• 0: success

• Non-zero: an error occurred

For other values refer to the Error codes

API#

/* Function */  
struct gecko_msg_gatt_discover_primary_services_by_uuid_rsp_t *gecko_cmd_gatt_discover_primary_services_by_uuid(uint8 connection, uint8 uuid_len, const uint8 *uuid_data);  
  
/* Response id */  
gecko_rsp_gatt_discover_primary_services_by_uuid_id  
  
/* Response structure */  
struct gecko_msg_gatt_discover_primary_services_by_uuid_rsp_t  
{  
  uint16 result  
}  

Events generated#

gatt_execute_characteristic_value_write#

This command can be used to commit or cancel previously queued writes to a long characteristic of a remote GATT server. Writes are sent to queue with prepare_characteristic_value_write command. Content, offset and length of queued values are validated by this procedure. A received gatt_procedure_completed event indicates that all data has been written successfully or that an error response has been received.

Command#

Response#

• 0: success

• Non-zero: an error occurred

For other values refer to the Error codes

API#

/* Function */  
struct gecko_msg_gatt_execute_characteristic_value_write_rsp_t *gecko_cmd_gatt_execute_characteristic_value_write(uint8 connection, uint8 flags);  
  
/* Response id */  
gecko_rsp_gatt_execute_characteristic_value_write_id  
  
/* Response structure */  
struct gecko_msg_gatt_execute_characteristic_value_write_rsp_t  
{  
  uint16 result  
}  

Events generated#

gatt_find_included_services#

This command can be used to find out if a service of a remote GATT database includes one or more other services. This command generates a unique gatt_service_completed event for each included service. This command generates a unique gatt_service event for every discovered service. Received gatt_procedure_completed event indicates that this GATT procedure has successfully completed or failed with error.

Command#

This value is normally received from the gatt_service event.

Response#

• 0: success

• Non-zero: an error occurred

For other values refer to the Error codes

API#

/* Function */  
struct gecko_msg_gatt_find_included_services_rsp_t *gecko_cmd_gatt_find_included_services(uint8 connection, uint32 service);  
  
/* Response id */  
gecko_rsp_gatt_find_included_services_id  
  
/* Response structure */  
struct gecko_msg_gatt_find_included_services_rsp_t  
{  
  uint16 result  
}  

Events generated#

gatt_prepare_characteristic_value_reliable_write#

This command can be used to add a characteristic value to the write queue of a remote GATT server and verify if the value was correctly received by the server. Received gatt_procedure_completed event indicates that this GATT procedure has succesfully completed or failed with error. Specifically, error code 0x0194 (data_corrupted) will be returned if the value received from the GATT server's response failed to pass the reliable write verification. At most ATT_MTU - 5 amount of data can be sent once. Writes are executed or cancelled with the execute_characteristic_value_write command. Whether the writes succeeded or not are indicated in the response of the execute_characteristic_value_write command.

Command#

This value is normally received from the gatt_characteristic event.

7-8 | uint16 | offset | Offset of the characteristic value
9 | uint8array | value | Value to write into the specified characteristic of the remote GATT database

Response#

• 0: success

• Non-zero: an error occurred

For other values refer to the Error codes
6-7 | uint16 | sent_len | The length of data sent to the remote GATT server

API#

/* Function */  
struct gecko_msg_gatt_prepare_characteristic_value_reliable_write_rsp_t *gecko_cmd_gatt_prepare_characteristic_value_reliable_write(uint8 connection, uint16 characteristic, uint16 offset, uint8 value_len, const uint8 *value_data);  
  
/* Response id */  
gecko_rsp_gatt_prepare_characteristic_value_reliable_write_id  
  
/* Response structure */  
struct gecko_msg_gatt_prepare_characteristic_value_reliable_write_rsp_t  
{  
  uint16 result,  
  uint16 sent_len  
}  

Events generated#

gatt_prepare_characteristic_value_write#

This command can be used to add a characteristic value to the write queue of a remote GATT server. This command can be used in cases where very long attributes need to be written, or a set of values needs to be written atomically. At most ATT_MTU - 5 amount of data can be sent once. Writes are executed or cancelled with the execute_characteristic_value_write command. Whether the writes succeeded or not are indicated in the response of the execute_characteristic_value_write command.

In all cases where the amount of data to transfer fits into the BGAPI payload the command gatt_write_characteristic_value is recommended for writing long values since it transparently performs the prepare_write and execute_write commands.

Command#

This value is normally received from the gatt_characteristic event.

7-8 | uint16 | offset | Offset of the characteristic value
9 | uint8array | value | Value to write into the specified characteristic of the remote GATT database

Response#

• 0: success

• Non-zero: an error occurred

For other values refer to the Error codes
6-7 | uint16 | sent_len | The length of data sent to the remote GATT server

API#

/* Function */  
struct gecko_msg_gatt_prepare_characteristic_value_write_rsp_t *gecko_cmd_gatt_prepare_characteristic_value_write(uint8 connection, uint16 characteristic, uint16 offset, uint8 value_len, const uint8 *value_data);  
  
/* Response id */  
gecko_rsp_gatt_prepare_characteristic_value_write_id  
  
/* Response structure */  
struct gecko_msg_gatt_prepare_characteristic_value_write_rsp_t  
{  
  uint16 result,  
  uint16 sent_len  
}  

Events generated#

gatt_read_characteristic_value#

This command can be used to read the value of a characteristic from a remote GATT database. A single gatt_characteristic_value event is generated if the characteristic value fits in one ATT PDU. Otherwise more than one gatt_characteristic_value events are generated because the firmware will automatically use the "read long" GATT procedure. A received gatt_procedure_completed event indicates that all data has been read successfully or that an error response has been received.

Note that the GATT client does not verify if the requested atrribute is a characteristic value. Thus before calling this command the application should make sure the attribute handle is for a characteristic value in some means, for example, by performing characteristic discovery.

Command#

This value is normally received from the gatt_characteristic event.

Response#

• 0: success

• Non-zero: an error occurred

For other values refer to the Error codes

API#

/* Function */  
struct gecko_msg_gatt_read_characteristic_value_rsp_t *gecko_cmd_gatt_read_characteristic_value(uint8 connection, uint16 characteristic);  
  
/* Response id */  
gecko_rsp_gatt_read_characteristic_value_id  
  
/* Response structure */  
struct gecko_msg_gatt_read_characteristic_value_rsp_t  
{  
  uint16 result  
}  

Events generated#

gatt_read_characteristic_value_by_uuid#

This command can be used to read the characteristic value of a service from a remote GATT database by giving the UUID of the characteristic and the handle of the service containing this characteristic. A single gatt_characteristic_value event is generated if the characteristic value fits in one ATT PDU. Otherwise more than one gatt_characteristic_value events are generated because the firmware will automatically use the "read long" GATT procedure. A received gatt_procedure_completed event indicates that all data has been read successfully or that an error response has been received.

Command#

This value is normally received from the gatt_service event.

9 | uint8array | uuid | Characteristic UUID

Response#

• 0: success

• Non-zero: an error occurred

For other values refer to the Error codes

API#

/* Function */  
struct gecko_msg_gatt_read_characteristic_value_by_uuid_rsp_t *gecko_cmd_gatt_read_characteristic_value_by_uuid(uint8 connection, uint32 service, uint8 uuid_len, const uint8 *uuid_data);  
  
/* Response id */  
gecko_rsp_gatt_read_characteristic_value_by_uuid_id  
  
/* Response structure */  
struct gecko_msg_gatt_read_characteristic_value_by_uuid_rsp_t  
{  
  uint16 result  
}  

Events generated#

gatt_read_characteristic_value_from_offset#

This command can be used to read a partial characteristic value with specified offset and maximum length from a remote GATT database. It is equivalent to gatt_read_characteristic_value if both the offset and maximum length parameters are 0. A single gatt_characteristic_value event is generated if the value to read fits in one ATT PDU. Otherwise more than one gatt_characteristic_value events are generated because the firmware will automatically use the "read long" GATT procedure. A received gatt_procedure_completed event indicates that all data has been read successfully or that an error response has been received.

Command#

This value is normally received from the gatt_characteristic event.

7-8 | uint16 | offset | Offset of the characteristic value
9-10 | uint16 | maxlen | Maximum bytes to read. If this parameter is 0 all characteristic value starting at given offset will be read.

Response#

• 0: success

• Non-zero: an error occurred

For other values refer to the Error codes

API#

/* Function */  
struct gecko_msg_gatt_read_characteristic_value_from_offset_rsp_t *gecko_cmd_gatt_read_characteristic_value_from_offset(uint8 connection, uint16 characteristic, uint16 offset, uint16 maxlen);  
  
/* Response id */  
gecko_rsp_gatt_read_characteristic_value_from_offset_id  
  
/* Response structure */  
struct gecko_msg_gatt_read_characteristic_value_from_offset_rsp_t  
{  
  uint16 result  
}  

Events generated#

gatt_read_descriptor_value#

This command can be used to read the descriptor value of a characteristic in a remote GATT database. A single gatt_descriptor_value event is generated if the descriptor value fits in one ATT PDU. Otherwise more than one gatt_descriptor_value events are generated because the firmware will automatically use the "read long" GATT procedure. A received gatt_procedure_completed event indicates that all data has been read successfully or that an error response has been received.

Command#

Response#

• 0: success

• Non-zero: an error occurred

For other values refer to the Error codes

API#

/* Function */  
struct gecko_msg_gatt_read_descriptor_value_rsp_t *gecko_cmd_gatt_read_descriptor_value(uint8 connection, uint16 descriptor);  
  
/* Response id */  
gecko_rsp_gatt_read_descriptor_value_id  
  
/* Response structure */  
struct gecko_msg_gatt_read_descriptor_value_rsp_t  
{  
  uint16 result  
}  

Events generated#

gatt_read_multiple_characteristic_values#

This command can be used to read the values of multiple characteristics from a remote GATT database at once. The GATT server will return the values in one ATT PDU as the response. If the total set of values is greater than (ATT_MTU -

1. bytes in length, only the first (ATT_MTU - 1) bytes are included. A single gatt_characteristic_value event is generated, in which the characteristic is set to 0 and the data in value parameter is a concatenation of characteristic values in the order they were requested. Received gatt_procedure_completed event indicates that this GATT procedure has successfully completed or failed with error.

This command should be used only for characteristics values that have known fixed size, except the last one that could have variable length.

Command#

Response#

• 0: success

• Non-zero: an error occurred

For other values refer to the Error codes

API#

/* Function */  
struct gecko_msg_gatt_read_multiple_characteristic_values_rsp_t *gecko_cmd_gatt_read_multiple_characteristic_values(uint8 connection, uint8 characteristic_list_len, const uint8 *characteristic_list_data);  
  
/* Response id */  
gecko_rsp_gatt_read_multiple_characteristic_values_id  
  
/* Response structure */  
struct gecko_msg_gatt_read_multiple_characteristic_values_rsp_t  
{  
  uint16 result  
}  

Events generated#

gatt_send_characteristic_confirmation#

This command must be used to send a characteristic confirmation to a remote GATT server after receiving an indication. The gatt_characteristic_value_event carries the att_opcode containing handle_value_indication (0x1d) which reveals that an indication has been received and this must be confirmed with this command. Confirmation needs to be sent within 30 seconds, otherwise the GATT transactions between the client and the server are discontinued.

Command#

Response#

• 0: success

• Non-zero: an error occurred

For other values refer to the Error codes

API#

/* Function */  
struct gecko_msg_gatt_send_characteristic_confirmation_rsp_t *gecko_cmd_gatt_send_characteristic_confirmation(uint8 connection);  
  
/* Response id */  
gecko_rsp_gatt_send_characteristic_confirmation_id  
  
/* Response structure */  
struct gecko_msg_gatt_send_characteristic_confirmation_rsp_t  
{  
  uint16 result  
}  

gatt_set_characteristic_notification#

This command can be used to enable or disable the notifications and indications being sent from a remote GATT server. This procedure discovers a characteristic client configuration descriptor and writes the related configuration flags to a remote GATT database. A received gatt_procedure_completed event indicates that this GATT procedure has successfully completed or that is has failed with an error.

Command#

This value is normally received from the gatt_characteristic event.

7 | uint8 | flags | Characteristic client configuration flags

Response#

• 0: success

• Non-zero: an error occurred

For other values refer to the Error codes

API#

/* Function */  
struct gecko_msg_gatt_set_characteristic_notification_rsp_t *gecko_cmd_gatt_set_characteristic_notification(uint8 connection, uint16 characteristic, uint8 flags);  
  
/* Response id */  
gecko_rsp_gatt_set_characteristic_notification_id  
  
/* Response structure */  
struct gecko_msg_gatt_set_characteristic_notification_rsp_t  
{  
  uint16 result  
}  

Events generated#

gatt_set_max_mtu#

This command can be used to set the maximum size of ATT Message Transfer Units (MTU). If the given value is too large according to the maximum BGAPI payload size, the system will select the maximal possible value as the maximum ATT_MTU. If maximum ATT_MTU is larger than 23, MTU is exchanged automatically after a Bluetooth connection has been established.

Command#

• Range: 23 to 250

Default: 247

Response#

• 0: success

• Non-zero: an error occurred

For other values refer to the Error codes
6-7 | uint16 | max_mtu | The maximum ATT_MTU selected by the system if this command succeeded

API#

/* Function */  
struct gecko_msg_gatt_set_max_mtu_rsp_t *gecko_cmd_gatt_set_max_mtu(uint16 max_mtu);  
  
/* Response id */  
gecko_rsp_gatt_set_max_mtu_id  
  
/* Response structure */  
struct gecko_msg_gatt_set_max_mtu_rsp_t  
{  
  uint16 result,  
  uint16 max_mtu  
}  

gatt_write_characteristic_value#

This command can be used to write the value of a characteristic in a remote GATT database. If the given value does not fit in one ATT PDU, "write long" GATT procedure is used automatically. Received gatt_procedure_completed event indicates that all data has been written successfully or that an error response has been received.

Command#

This value is normally received from the gatt_characteristic event.

7 | uint8array | value | Characteristic value

Response#

• 0: success

• Non-zero: an error occurred

For other values refer to the Error codes

API#

/* Function */  
struct gecko_msg_gatt_write_characteristic_value_rsp_t *gecko_cmd_gatt_write_characteristic_value(uint8 connection, uint16 characteristic, uint8 value_len, const uint8 *value_data);  
  
/* Response id */  
gecko_rsp_gatt_write_characteristic_value_id  
  
/* Response structure */  
struct gecko_msg_gatt_write_characteristic_value_rsp_t  
{  
  uint16 result  
}  

Events generated#

gatt_write_characteristic_value_without_response#

This command can be used to write the value of a characteristic in a remote GATT server. This command does not generate any event. All failures on the server are ignored silently. For example, if an error is generated in the remote GATT server and the given value is not written into database no error message will be reported to the local GATT client. Note that this command cannot be used to write long values. At most ATT_MTU - 3 amount of data can be sent once.

Command#

This value is normally received from the gatt_characteristic event.

7 | uint8array | value | Characteristic value

Response#

• 0: success

• Non-zero: an error occurred

For other values refer to the Error codes
6-7 | uint16 | sent_len | The length of data sent to the remote GATT server

API#

/* Function */  
struct gecko_msg_gatt_write_characteristic_value_without_response_rsp_t *gecko_cmd_gatt_write_characteristic_value_without_response(uint8 connection, uint16 characteristic, uint8 value_len, const uint8 *value_data);  
  
/* Response id */  
gecko_rsp_gatt_write_characteristic_value_without_response_id  
  
/* Response structure */  
struct gecko_msg_gatt_write_characteristic_value_without_response_rsp_t  
{  
  uint16 result,  
  uint16 sent_len  
}  

gatt_write_descriptor_value#

This command can be used to write the value of a characteristic descriptor in a remote GATT database. If the given value does not fit in one ATT PDU, "write long" GATT procedure is used automatically. Received gatt_procedure_completed event indicates that all data has been written succesfully or that an error response has been received.

Command#

Response#

• 0: success

• Non-zero: an error occurred

For other values refer to the Error codes

API#

/* Function */  
struct gecko_msg_gatt_write_descriptor_value_rsp_t *gecko_cmd_gatt_write_descriptor_value(uint8 connection, uint16 descriptor, uint8 value_len, const uint8 *value_data);  
  
/* Response id */  
gecko_rsp_gatt_write_descriptor_value_id  
  
/* Response structure */  
struct gecko_msg_gatt_write_descriptor_value_rsp_t  
{  
  uint16 result  
}  

Events generated#

gatt events#

gatt_mtu_exchanged#

This event indicates that an ATT_MTU exchange procedure has been completed. Parameter mtu describes new MTU size. MTU size 23 is used before this event is received.

Event#

API#

/* event id*/  
gecko_evt_gatt_mtu_exchanged_id  
  
/* event structure*/  
struct gecko_msg_gatt_mtu_exchanged_evt_t  
{  
  uint8 connection,  
  uint16 mtu  
}  

gatt_service#

This event indicates that a GATT service in the remote GATT database was discovered. This event is generated after issuing either the gatt_discover_primary_services or gatt_discover_primary_services_by_uuid command.

Event#

API#

/* event id*/  
gecko_evt_gatt_service_id  
  
/* event structure*/  
struct gecko_msg_gatt_service_evt_t  
{  
  uint8 connection,  
  uint32 service,  
  uint8array uuid  
}  

gatt_characteristic#

This event indicates that a GATT characteristic in the remote GATT database was discovered. This event is generated after issuing either the gatt_discover_characteristics or gatt_discover_characteristics_by_uuid command.

Event#

API#

/* event id*/  
gecko_evt_gatt_characteristic_id  
  
/* event structure*/  
struct gecko_msg_gatt_characteristic_evt_t  
{  
  uint8 connection,  
  uint16 characteristic,  
  uint8 properties,  
  uint8array uuid  
}  

gatt_descriptor#

This event indicates that a GATT characteristic descriptor in the remote GATT database was discovered. This event is generated after issuing the gatt_discover_descriptors command.

Event#

API#

/* event id*/  
gecko_evt_gatt_descriptor_id  
  
/* event structure*/  
struct gecko_msg_gatt_descriptor_evt_t  
{  
  uint8 connection,  
  uint16 descriptor,  
  uint8array uuid  
}  

gatt_characteristic_value#

This event indicates that the value of one or several characteristics in the remote GATT server was received. This event is triggered as a result of several commands: gatt_read_characteristic_value, gatt_read_characteristic_value_from_offset, gatt_read_characteristic_value_by_uuid, gatt_read_multiple_characteristic_values; and when the remote GATT server sends indications or notifications after enabling notifications with gatt_set_characteristic_notification. The parameter att_opcode reveals which type of GATT transaction triggered this event. In particular, if the att_opcode type is handle_value_indication (0x1d), the application needs to confirm the indication with gatt_send_characteristic_confirmation.

Event#

This value is normally received from the gatt_characteristic event.

7 | uint8 | att_opcode | Attribute opcode which informs the GATT transaction used
8-9 | uint16 | offset | Value offset
10 | uint8array | value | Characteristic value

API#

/* event id*/  
gecko_evt_gatt_characteristic_value_id  
  
/* event structure*/  
struct gecko_msg_gatt_characteristic_value_evt_t  
{  
  uint8 connection,  
  uint16 characteristic,  
  [uint8 att_opcode](gatt#enum_gatt_att_opcode),  
  uint16 offset,  
  uint8array value  
}  

gatt_descriptor_value#

This event indicates that the value of a descriptor in the remote GATT server was received. This event is generated by the gatt_read_descriptor_value command.

Event#

API#

/* event id*/  
gecko_evt_gatt_descriptor_value_id  
  
/* event structure*/  
struct gecko_msg_gatt_descriptor_value_evt_t  
{  
  uint8 connection,  
  uint16 descriptor,  
  uint16 offset,  
  uint8array value  
}  

gatt_procedure_completed#

This event indicates that the current GATT procedure has been completed successfully or that it has failed with an error. All GATT commands excluding gatt_write_characteristic_value_without_response and gatt_send_characteristic_confirmation will trigger this event, so the application must wait for this event before issuing another GATT command (excluding the two aforementioned exceptions).

Event#

• 0: success

• Non-zero: an error occurred

For other values refer to the Error codes

API#

/* event id*/  
gecko_evt_gatt_procedure_completed_id  
  
/* event structure*/  
struct gecko_msg_gatt_procedure_completed_evt_t  
{  
  uint8 connection,  
  uint16 result  
}  

gatt enumerations#

gatt_att_opcode#

These values indicate which attribute request or response has caused the event.

Enumerations#

gatt_client_config_flag#

These values define whether the client is to receive notifications or indications from a remote GATT server.

Enumerations#

gatt_execute_write_flag#

These values define whether the GATT server is to cancel all queued writes or commit all queued writes to a remote database.

Enumerations#