Updating Advertising Service Data

[jloliveira]

Good afternoon,

I'm running advertising with a uint16_t service data associated with a 16-bit service UUID.

I would like to update the service data regularly without the need to update the whole advertising package.

Is there a way to do this similarly to the flags_set() function in the BLE Advertising Module? When I try to accomplish it by recurring to "uint8_t * p_service_data = ble_advdata_parse(p_advertising->adv_data.adv_data.p_data, p_advertising->adv_data.adv_data.len, BLE_GAP_AD_TYPE_SERVICE_DATA)" I can never return the correct offset in the advertising data related to the Service Data field - it always returns 0 offset - and therefore can't access the actual Service Data to update it. Any suggestions to accomplish this?

Thank you,

João

[jloliveira]

Hi Martin,

Thank you for your reply.

I'm totally sure the advertising packet contains the ServiceData and it is working as expected. I'm updating the whole advertising data everytime I need to update the ServiceData and it works perfectly.

Any queues what might be wrong?

Thank you,

João

[MartinBL]

Not sure what it can be. Do you mind sharing your code? We can make the case private if you prefer confidentiality. 

[jloliveira]

Hi Martin,

I tried to import your sdata_set function and it results the same => offset is always zero and thus p_sdata is never different than NULL.

I checked p_advertising->adv_data.adv_data.len and it is always 31.

Do you have any idea what might be the problem?

Thanks,

João

[MartinBL]

That is strange.

1. What SDK version are you using?
2. Can you share your entire project? We can make the case private if you prefer confidentiality. 

[jloliveira]

Hi Martin,

It seems that I had an issue with p_advertising->adv_data.adv_data.len indeed, which was getting unintentionally altered and reading the ServiceData "out of range".

It is now working but I'm struggling with the NRF_ERROR_INVALID_STATE with sd_ble_gap_adv_set_configure. According to the documentation, "It is invalid to provide the same data buffers while advertising. To update advertising data, provide new advertising buffers."

I try to contour the issue with the code in attachment but still retrieve the same error. Any ideas to solve it?

 

I'm using SDK15 and Softdevice6.0.0

Thank you,

João

ret_code_t sdata_set(ble_advertising_t * const p_advertising, uint16_t sdata)
{
    uint32_t ret;
    
    uint8_t * p_sdata = ble_advdata_parse(p_advertising->adv_data.adv_data.p_data,
				      p_advertising->adv_data.adv_data.len,
				      BLE_GAP_AD_TYPE_SERVICE_DATA);
    
    uint16_t offset = 0;
    if (p_sdata != NULL)
    {
			*p_sdata = sdata;

			ble_advdata_search(p_advertising->adv_data.adv_data.p_data, BLE_GAP_ADV_SET_DATA_SIZE_MAX, &offset, BLE_GAP_AD_TYPE_SERVICE_DATA);
			
        	offset+=2; //To get the data itself			
			p_advertising->adv_data.adv_data.p_data[offset++] = MSB_16(sdata);
        	p_advertising->adv_data.adv_data.p_data[offset++] = LSB_16(sdata);
    }
    else //Debug
    {
			NRF_LOG_ERROR("No SData!");
    }
    

    if(m_advdata_idx % 2 == 0)
    {
            memcpy(m_new_enc_advdata1, p_advertising->adv_data.adv_data.p_data, p_advertising->adv_data.adv_data.len);
            m_new_adv_data.adv_data.p_data      = m_new_enc_advdata1;
            m_new_adv_data.adv_data.len         = p_advertising->adv_data.adv_data.len;

            m_new_adv_data.scan_rsp_data.p_data = p_advertising->enc_scan_rsp_data;
            m_new_adv_data.scan_rsp_data.len    = p_advertising->adv_data.scan_rsp_data.len;
    }
    else
    {
            memcpy(m_new_enc_advdata2, p_advertising->adv_data.adv_data.p_data, p_advertising->adv_data.adv_data.len);
            m_new_adv_data.adv_data.p_data      = m_new_enc_advdata2;
            m_new_adv_data.adv_data.len         = p_advertising->adv_data.adv_data.len;

            m_new_adv_data.scan_rsp_data.p_data = p_advertising->enc_scan_rsp_data;
            m_new_adv_data.scan_rsp_data.len    = p_advertising->adv_data.scan_rsp_data.len;
    }

    m_advdata_idx++;

    memcpy(&p_advertising->adv_data, &m_new_adv_data, sizeof(p_advertising->adv_data));
    p_advertising->p_adv_data = &p_advertising->adv_data;

    ret = sd_ble_gap_adv_set_configure(&p_advertising->adv_handle, &p_advertising->adv_data, &p_advertising->adv_params);

    return ret;
}

[MartinBL]

Hi,

Unfortunately there is no elegant way of updating the data in the advertising packet while advertising. You need to stop advertising, reconfigure the packet, and restart advertising again.

[jloliveira]

Hi Martin,

I could do the whole data update when considering a similar strategy by interleaving two different pointers that are passed to p_advertising->adv_data at each data update iteration. Yet, it is not working for the service_data update purpose, as implemented in the code I sent you.

Do you have any unelegant proposal to solve this issue? It seems like a limitation from the SDK that should be polished.

Thank you,

João

[MartinBL]

I'm not sure if I understand your question. My unelegant (and only) proposal is stop advertising and configure the advertising structure from scratch again each time you want to update the content.