Problem sending data array using BLE_NUS_DATA_SEND

[timothyeah]

Hi,

I am simply trying to send a sample of data from a TWI sensor to smartphone via BLE with a 2 second delay between each send.

I've adapted the ble_app_uart and twi_sensor examples, and everything is working properly except one thing. The data is not received properly.

The BLE_NUS_DATA_SEND is sending and working correctly because I do see the "value" title appear in the NRF Connect app after enabling notifications, but there is just no value there (just empty space).

To check the data, I printed/logged the sensor value in the data_send function. M_sample prints correctly, but when I try to print the data array, it doesn't show. So I believe this problem is caused when m_sample is put into the data array. This tells me that m_sample is of the wrong type or form.

I have 2 questions:

1. What type/size/form does my data need to be in to be printed/logged, and why can't I print the data_array but can with the m_sample?

2. What changes need to be applied to send my number sample (m_sample) via BLE_NUS_DATA_SEND?

 

I'm sure these questions are obvious to someone. I may have missed some basic things in the documentation, but I'd really appreciate if someone could point out my problem.

SDK15.3, SES

void data_send(uint8_t m_sample)
{
    static uint8_t data_array[BLE_NUS_MAX_DATA_LEN];
    static uint8_t index = 0;
    uint32_t       err_code;

    data_array[BLE_NUS_MAX_DATA_LEN - 1] = m_sample;


NRF_LOG_INFO("check msample: %d Celsius degrees.", m_sample);

       // NRF_LOG_INFO("Check array.", data_array); 
          NRF_LOG_INFO("Check array2.", m_sample); 
          
                    //NRF_LOG_DEBUG("Ready to send data over BLE NUS");
                    //NRF_LOG_HEXDUMP_DEBUG(data_array, index);

                   
                        uint16_t length = (uint16_t)index;
                        err_code = ble_nus_data_send(&m_nus, &data_array, &length, m_conn_handle);
  
 

   if ((err_code != NRF_ERROR_INVALID_STATE) &&// This part is right (saw another user do it).
                            (err_code != NRF_ERROR_RESOURCES) &&
                            (err_code != NRF_ERROR_NOT_FOUND))//different
                        {
                            APP_ERROR_CHECK(err_code);
                      }

}

[Edvin]

Hello,

Your line:

NRF_LOG_INFO("Check array2.", m_sample); 

doesn't know where to put m_sample. I assume you want to change this to:

NRF_LOG_INFO("Check array2 %d", m_sample); 

Also, try to add this line after the line err_code = ble_nus_data_send(...);

NRF_LOG_INFO("ble_nus_data_send returned %d", err_code);

Just to see what it returns.

[timothyeah]

Hi, 

Thanks for that! Now the values are printing correctly. But I still don't understand how to insert m_sample into an array of correct type and send it using ble_nus_data_send. 

The err_code for ble_nus_data_send returns "5"

[awneil]

timothyeah said:

I still don't understand how to insert m_sample into an array of correct type

See replies below.

This part is just standard 'C' - not specific to Nordic.