Send Data packets of about 50 bytes from central to a peripheral device with or without establishing a connection

[GO_D]

Hello 

I am using SDK15.3 and nrf52832 development board. 

In my setup,

1. I have a  few peripheral nodes whose only job is to transmit some arbitrary packets ( say P),

2. a node that acts as both central and peripheral( say T) which reads the advertisement packets from P and gets it RSSI values and then sends this RSSI array ( from mulitple P nodes) to a  gateway(say G), which is a central node.

My issues are

a)  Setting up this node T. Please suggest which example from SDK 15.0 and higher is suitable for this.

b) How to send data from 'T' to 'G'. The size of data is about 40 bytes. I realised the data sent in the advertisement as manuf_data is about 15 bytes ( correct me if I'm wrong about this). So how to send data after establishing a connection? Please suggest suitable examples.

Thank you in advance. 

[Kenneth]

Typically the lates SDK is the preferred one, so currently SDKv15.3 is the latest.

An example that can be used as reference may be:
https://infocenter.nordicsemi.com/topic/com.nordic.infocenter.sdk5.v15.3.0/ble_sdk_app_rscs_relay.html?cp=5_1_4_2_1_2 

Though for start it may be good to get familiar with the BLE Blinky (use buttons and LEDs as IO) or NUS (use UART as IO) example:
https://infocenter.nordicsemi.com/topic/com.nordic.infocenter.sdk5.v15.3.0/ble_sdk_app_blinky.html?cp=5_1_4_2_2_3
https://infocenter.nordicsemi.com/topic/com.nordic.infocenter.sdk5.v15.3.0/ble_sdk_app_nus_eval.html?cp=5_1_4_2_2_24 

Once you get familiar scanning in central role and exchanging data over BLE in peripheral role you should be good to go.

Best regards,
Kenneth

[GO_D]

Thank you sir. I will go through those examples. Meanwhile, I'm unable to send data packets using NUS. I have tried many hints from the Devzone itself, but it is not helping. Please brief me on how to go about using NUS to send and receive data packets, WITHOUT USING SERIAL interface. 

Thank You.

[awneil]

GO_D said:

So, declared the array

but what have you actually done with that array?!

How to properly post source code:

[GO_D]

/**@brief   Function for handling app_uart events.
 *
 * @details This function receives a single character from the app_uart module and appends it to
 *          a string. The string is sent over BLE when the last character received is a
 *          'new line' '\n' (hex 0x0A) or if the string reaches the maximum data length.
 */
void uart_event_handle(app_uart_evt_t * p_event)
{
    //added
    NRF_LOG_INFO("in uart_evt_handle\r\n");
    //static uint8_t data_array[BLE_NUS_MAX_DATA_LEN];
    static uint8_t data_array[BLE_NUS_MAX_DATA_LEN] = "1,2,3\r\n";
    NRF_LOG_INFO("array = %x\r\n",data_array);
    static uint16_t index = 0;
    uint32_t ret_val;

[GO_D]

Sorry for that awneil. I have put up the code below. I have put the array in a string format, as the comment above the function says it will send the string if it is of max length or ends with \n

[awneil]

You've still just shown the definition of the array - you haven't show how you actually use it!

[GO_D]

Okay. I have declared the data_array[BLE_NUS_MAX_DATA_LEN] in the function  uart_event_handle(app_uart_evt_t * p_event)

and i am passing it as a parameter in the function 

 ble_nus_c_string_send(&m_ble_nus_c, data_array, index);

void uart_event_handle(app_uart_evt_t * p_event)
{
    //added
    NRF_LOG_INFO("in uart_evt_handle\r\n");
    //static uint8_t data_array[BLE_NUS_MAX_DATA_LEN];
    static uint8_t data_array[BLE_NUS_MAX_DATA_LEN] = "1,2,3\r\n";
    NRF_LOG_INFO("array = %x\r\n",data_array);
    static uint16_t index = 0;
    uint32_t ret_val;

    switch (p_event->evt_type)
    {
        /**@snippet [Handling data from UART] */
        case APP_UART_DATA_READY:
            UNUSED_VARIABLE(app_uart_get(&data_array[index]));
            index++;

            if ((data_array[index - 1] == '\n') || (index >= (m_ble_nus_max_data_len)))
            {
                NRF_LOG_DEBUG("Ready to send data over BLE NUS");
                NRF_LOG_INFO("Ready to send data over BLE NUS");
                NRF_LOG_HEXDUMP_DEBUG(data_array, index);

                do
                {
                    ret_val = ble_nus_c_string_send(&m_ble_nus_c, data_array, index);
                    if ( (ret_val != NRF_ERROR_INVALID_STATE) && (ret_val != NRF_ERROR_RESOURCES) )
                    {
                        APP_ERROR_CHECK(ret_val);
                    }
                } while (ret_val == NRF_ERROR_RESOURCES);

                index = 0;
            }
            break;

Also, I am definitely not sure if this is the right way. Please suggest me with an alternative way to send an array between UART central and peripheral nodes.

[awneil]

What do you think the 'index' variable is doing there?

I think you need to spend some more time understanding what the original example is doing before trying to modify it.

Use your IDE's browsing facility to find the declaration (not the definition) of ble_nus_c_string_send() - the comments there tell you what the parameters are ...