nRF52 ble to ble transfer continuous data for

Question

Hello!! 
 We are carrying out a project using nRF52832 , in which we must send a data to a phone every 1 second for 10 hours. The data sent is a sequence of numbers from 1 to 36000 (counting every second that passes). 
 The sending of data must be through ble. 
 We have been looking for information and have seen on the nordic website that 
 ble_nus_data_send(); 
 is the most efficient, fast and secure function for sending and receiving data via ble. 
 1. We want to ask just to make sure this is right? 
 2. If the above question is correct, this function should be used in static void on_ble_evt() ? 
 
 On the other hand, we want the phone to also be sending data to nRF52832 (the same number sequence with the same sample): 
 3. Is it possible to be sending and receiving at the same time in nRF52832? or should there be a time gap between receiving and sending? 
 4. What is the best way to receive data in nRF52832 continuously and for so long? 
 
 Thank you very much for your time and help!

Simon · Accepted Answer

Q1 
 If the nRF52832 is the GATT server and the phone is the GATT client (read about the roles here ) the way to send data to the phone, is through notifications, and that is done through the call sd_ble_gatts_hvx(). The function ble_nus_data_send() (nRF5_SDK_17.0.0_9d13099\components\ble\ble_services\ble_nus\ble_nus.c) is an abstraction layer on top of that, which will notify to the TX characteristic of the NUS Service. So ble_nus_data_send() should be the best option for you, if: You want to use the NUS service (which seems like a good choice regarding your end goal) and if nRF52832 is a server. 
 
 This function can not be used for receiving data, only notifying data to the client 
 
 Q2 
 You should not use ble_nus_data_send() in on_ble_evt(..) . To reach your end goal of sending a value every 10 seconds, you should make some kind of timer and run it every 10 seconds instead. 
 
 Q3 
 
 Yes, this should be possible. You should not worry about adding any delay, as the SofDevice will handle the scheduling. 
 Q4 
 If the nRF52832 is the server and the phone is the client, the WRITE operation needs to be used. To receive the WRITEs on the server (nrf52832), you need to set up an observer function with NRF_SDH_BLE_OBSERVER() and look for the BLE_GATTS_EVT_WRITE events. However, in the ble_app_uart example, this is done and you will receive the writes in the function nRF5_SDK_17.0.0_9d13099\examples\ble_peripheral\ble_app_uart\main.c-->nus_data_handler() 
 
 I would recommend you to check out the sample nRF5_SDK_17.0.0_9d13099\examples\ble_peripheral\ble_app_uart and go through the steps under Testing , which demonstrates how you can send data forth and back between a phone (using nRF Connect ) and an nRF52832.

These tutorials may also be useful: 
 
 https://devzone.nordicsemi.com/nordic/short-range-guides/b/bluetooth-low-energy/posts/ble-advertising-a-beginners-tutorial 
 https://devzone.nordicsemi.com/nordic/short-range-guides/b/bluetooth-low-energy/posts/ble-characteristics-a-beginners-tutorial 
 https://devzone.nordicsemi.com/nordic/short-range-guides/b/bluetooth-low-energy/posts/ble-services-a-beginners-tutorial 
 
 Best regards, 
 Simon

nRF52 ble to ble transfer continuous data for

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