NUS central and DFU using Serialization

[TS Gowtham]

Hi,

I'm using 2 nRF52832s in my project. One of them is connected to a PC serially and has NUS central running on it and the other nRF52 connects to this central. I was able to get the HRM example running with the connectivity firmware on the nRF52 which is connected serially to the PC.

1. Similar to the Serialized HRM example, are there any examples of NUS central which I can use with the HCI BLE connectivity firmware?

2. I would also like to use the nRF52 which will be running the connectivity firmware as an intermediary to perform a DFU on the peripheral nRF52. Is this possible?

Thanks

[TS Gowtham]

Hi again and sorry for the delay in replying,

As you suggested I am using the Heart Rate Collector example as the base of my project. But since I am trying to implement NUS, I will need to use UART to transmit the data from the NUS service to my PC. How should I go about this and what kind of effects and changes will this have on the connectivity firmware?

[Vidar Berg]

Hi,

No worries. I don't think you'll  need to modify the connectivity FW as you will be receiving the NUS notifications through the on_notification() callback in your PC app. You could also use the nrfutil dfu ble transport implementation as reference in addition to the hrs collector example (https://github.com/NordicSemiconductor/pc-nrfutil/blob/master/nordicsemi/dfu/dfu_transport_ble.py). It shows how you can add 128 vendor specific UUIDs. 

 

[TS Gowtham]

Hi, the link you provided was quite helpful. But now I am currently trying to use the pc ble driver in C++ by modifying the given HRS collector example. Is there a similar code snippet which shows how to add the UUID? I guess I should use the sd_ble_uuid_vs_add function but I am not sure about if the UUID type which should be passed to the function be of type UNKOWN or VENDOR_BEGIN

[Vidar Berg]

Hi,

Correct, you should use sd_ble_uuid_vs_add() if you're not using the python/js wrapper. UUID type needs to be set to VENDOR_BEGIN. 

[TS Gowtham]

Thank you,

I got an approximate idea from the on_notification() function. If I am right, I guess it's function is similar to that of the function on_hvx()? This would solve the portion where the device receives data from the peripheral. But what about transmitting data from the nrf running the connectivity fw to the peripheral? Would just using sd_ble_gattc_write() directly work?

[Vidar Berg]

Yes you are right, notifications/indications will be reported through the on_hvx() function, and writes to the peripheral can be done by calling sd_ble_gattc_write() like you said. hrm_cccd_set() does this, but you may want to use write command instead of write request if you are writing to the NUS characteristic because it's faster.