Read/Write network core registers from application core

[nvelozsavino]

How can I read and/or write registers belonging to the Network core from the application core. I would like to do it without modifying the hci_rpmsg that is built by default. Is there a hci api to do this?

[JONATHAN LL]

Hi,

I am not able to find anything that seems to work the way you want, I believe you will have to modify the hci_rpmsg sample. 


Here are some links with relevant info:

https://infocenter.nordicsemi.com/topic/ps_nrf5340/chapters/soc_overview/doc/soc_overview.html?cp=3_0_0_2_0#blockdiagram 

Data transfer between APP core and Net core. - Nordic Q&A - Nordic DevZone - Nordic DevZone (nordicsemi.com) 

nRF53/nrfx: How to do Inter Processor Communication? - Nordic Q&A - Nordic DevZone - Nordic DevZone (nordicsemi.com) 

Access network core registers from app core - Nordic Q&A - Nordic DevZone - Nordic DevZone (nordicsemi.com) 

Regards,
Jonathan

[nvelozsavino]

Ok, I want to avoid modifying the hci_rpmsg image, I only need to access (read and write) 2 registers:

From FREQUENCY (0x41008508) we need and write FREQUENCY field

and  from  TXPOWER (0x4100850C) we would like to read and write the TXPOWER field

Is there a way to read/write these parameters using an already existing API?

[JONATHAN LL]

Hi, 

What is the goal, if you could explain what you are trying to to then maybe I could provide some better info. Is the goal to do PHY updates ?

There is a TXPOWER HCI command
https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/zephyr/samples/bluetooth/hci_pwr_ctrl/README.html 

Regards,
Jonathan

[nvelozsavino]

The device is a medical device, it seems the certification process requires to change these parameters to evaluate the impact on the body. I think in normal operation we won't allow to modify the frequency parameter. so it should be for certification purposes only. Is there a way to change this value with an API like the TXPOWER?

[JONATHAN LL]

We do have the radio test example, I recommend that you use that. 

Radio test — nRF Connect SDK 1.7.0 documentation (nordicsemi.com) 

sdk-nrf/samples/peripheral/radio_test at v1.7.0 · nrfconnect/sdk-nrf (github.com)

Regards,
Jonathan

[nvelozsavino]

But that replace the entire hci_rpmsg child image, in fact that sample doesn't even use the application core. What we need is to use the current hci_rpmsg image in the network core and add the capabiliy to modify the registers from the Application core.

Where's the hci_rpmsg source code? 
How can we create a project that compiles a custom child image?

[JONATHAN LL]

nvelozsavino said:

Where's the hci_rpmsg source code? 

zephyr/samples/bluetooth/hci_rpmsg is the location. 

nvelozsavino said:

How can we create a project that compiles a custom child image?

First, open a command prompt in the build folder of the network sample and enter the following command to erase the flash memory of the network core and program the network sample:

nrfjprog -f NRF53 --coprocessor CP_NETWORK --program zephyr/zephyr.hex --chiperase

Then navigate to the build folder of the application sample and enter the following command to erase the flash memory of the application core and program the application sample:

nrfjprog -f NRF53 --program zephyr/zephyr.hex --chiperase

Finally, reset the development kit:

nrfjprog --pinreset

You can build app core and net core separately and flash with nrfjprog. 

 Regards,
Jonathan