Zigbee - Discover Attribute Request / Response

[L.Hoffmann]

For a customer I am developing a Zigbee coordinator / Gateway with the nRF52840. As hardware I am using the nRF52840 Development Kit v2.0.1. As Software basis I use the “Zigbee cli example - Project” from the Thread and Zigbee SDK v4.0.0.

So far a lot of basic requests like “LQI” and “active endpoint” requests are working. But when I try to read out the Attributes of an endpoint I only get unexpected results as response.

As there are is no example for that in the cli Project, I only used the API Reference. I was able to send the request with my function “discover_attr_send(…)”. The function is called as callback after executing the api function “zb_buf_get_out_delayed_ext(…)”

static zb_void_t discover_attr_send(zb_bufid_t bufid, zb_uint16_t cb_param)

{

    zb_uint8_t row = cb_param;

    discover_attr_req_t * p_row = &(m_disc_attr_table[row]);

    p_row->seq_num = ZCL_CTX().seq_number;

    ZB_ZCL_GENERAL_DISC_READ_ATTR_REQ(bufid,                                                                                            

                                                                        ZB_ZCL_ENABLE_DEFAULT_RESPONSE,

                                                                        p_row->u16StartAttrID,

                                                                        p_row->u8MaxLen,

                                                                        p_row->u16TargetAddress,

                                                                        p_row->u8AddrMode,

                                                                        p_row->u8RemoteEP,

                                                                        zb_get_cli_endpoint(),

                                                                        ZB_AF_HA_PROFILE_ID,

                                                                        p_row->u16ClusterID,                                                                                                              

                                                                        cmd_zb_zcl_getDiscReadAtte_req_cb);

}

For example I want to read out the attributes of the On/Off Cluster (0x0006), endpoint 3 from the node with the short address “0x8dda”. So the parameters when sending the request look like this:

u16StartAttrID : 0

u8MaxLen : 11

u16TargetAddress : 0x8dda

u8AddrMode : 2

u8RemoteEP : 3

u16ClusterID : 6

As expected, after some time the callback function “cmd_zb_zcl_getDiscReadAtte_req_cb(…)” is called:

static zb_void_t cmd_zb_zcl_getDiscReadAtte_req_cb(zb_bufid_t bufid)

{

  zb_uint8_t complete = ZB_ZCL_DISC_NON_COMPLETE;

  zb_zcl_disc_attr_info_t *disc_attr_info;

 

  ZB_ZCL_GENERAL_GET_COMPLETE_DISC_RES(bufid, complete);

  ZB_ZCL_GENERAL_GET_NEXT_DISC_ATTR_RES(bufid, disc_attr_info);

  if (ZB_ZCL_DISC_COMPLETE == complete)

  {

    printf("Disc Attribute complete:\n ID: 0x%X\n Type: 0x%X\n", disc_attr_info->attr_id, disc_attr_info->data_type)

  }

  else

  {

  printf("Disc Attribute incomplete:\n ID: 0x%X\n Type: 0x%X\n", disc_attr_info->attr_id, disc_attr_info->data_type);

 } 

 zb_buf_free(bufid);

}

As result I always get an answers like this:

1. Time:

Disc Attribute incomplete:

 ID: 0xC00

 Type: 0x0

2. Time:

Disc Attribute incomplete:

 ID: 0xC01

 Type: 0x0

3. Time:

Disc Attribute incomplete:

 ID: 0xC02

 Type: 0x0

That was not something I was expecting to receive as Answer, as the IDs don’t match with attributes of the On/Off Cluster. Can you tell me what I am doing wrong? Do you have example code of how to read out the attributes of a cluster?

 

Best Regards

Lutz

[L.Hoffmann]

I guess I found part of the answer. The parameter for the callback function send with the ZB_ZCL_GENERAL_DISC_READ_ATTR_REQ request is “for getting command send status“. Ok, my fault.

But where and when should my function cmd_zb_zcl_getDiscReadAtte_req_cb(…) be called?

[Marjeris Romero]

Hi,

Have you seen CLI command 'zcl attr read' in the CLI example?

If you goal is to access the contents of the response package you need to intercept the ZCL response. You need to register a endpoint handler with ZB_AF_SET_ENDPOINT_HANDLER() to intercept the ZCL packets, see more information in here.

Inside the handler you should check the command direction, cluster ID and command ID, and call the dedicated API for getting the contents of the read attribute response frame ZB_ZCL_GENERAL_GET_NEXT_READ_ATTR_RES, then free the buffer and return ZB_TRUE, otherwise return ZB_FALSE to indicate to the stack to perform the default command processing. 

See "Implementing algorithm for overriding the handling of ZCL commands" in the link I provided above.

Best regards,

Marjeris

[L.Hoffmann]

Thanks, that helped a lot!

Best Regards

Lutz