nRF5340 IPC communication

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Hello,

I am using Nordic nRF Connect SDK v3.1.1 and nRF5340DK board.

My project is based on the project: GitHub - nordic-auko/nRF5-ble-timesync-demo: nRF52 clock synchronization demo code.

I added communication via BLE to timesync app and I built two separate applications based on timesync-demo sample. 
I have 2 applications:
- Receiever is receiving BLE data and sending synchronization data - I will have this application on one device
- Transmitter is sending BLE data and receiving synchronization - I will have this application on two or three devices

I want to use ADC and send data from transmitter to receiver (with time synchronization).
I found out that netcore (cpunet) does not have access to ADC, so what I did was that cpuapp collects data from the ADC and then sends it to cpunet using IPC.
My IPC communication is based on ipc_service from this path in SDK files: "\ncs\v3.1.1\nrf\samples\ipc\ipc_service".
I am using the same functions (ep_recv with small modification) to send and receive IPC messages on cpuapp and cpunet.
This functions are: ep_bound, ep_recv, ipc_service_open_instance, ipc_service_register_endpoint,  ipc_service_send.

Part of the application on cpuapp is ipc_service sample that is extended to collecting data from ADC, and sending this data to cpunet via IPC.
Part of the application on cpunet is timesync-demo that is extended to sending and receiving data via BLE, and receiving data from cpuapp via IPC.

I want to send ADC data from receiver to tramsmitter via BLE every 10 ms.

QUESTIONS: 

Will the IPC implementation slow down my application or is it fast enough that I can read data from the ADC on cpuapp every 10 ms (or even every 8 ms), then send it via IPC to cpunet, and then send it from cpunet to the receiver via BLE ?     [ each of these steps should occur every 10ms ]
How much data (how many Bytes) can be sent via IPC so that the transmission does not slow down the rest of the application ?

 

Can cpuapp and cpunet communication via IPC work both ways equally well (cpuapp -> cpunet or cpunet -> cpuapp) ?

If I want to establish two-way IPC communication, do I need to add additional mechanisms to avoid errors or data loss ?

Is the method of sending data via IPC presented in the "ipc_service" sample (extended to send data array from ADC) suitable for my purposes ?
Are there other better methods or perhaps different functions that should be used in the final application ?

 

Best Regards

 

[Kazi Afroza Sultana]

Hello,

''Will the IPC implementation slow down my application or is it fast enough that I can read data from the ADC on cpuapp every 10 ms (or even every 8 ms), then send it via IPC to cpunet, and then send it from cpunet to the receiver via BLE ?     [ each of these steps should occur every 10ms ]''

Yes, it is possible as ipc_service sample on nRF5340 sends 100-byte packets as fast as possible between the cores and reports throughput of 7.5 Mbit/s (application core) and 5.3 Mbit/s (network core)

IPC service

You just need to verify the BLE link budget and timing with your actual payload size and connection parameters. You can read the following documentation:

Choosing between Zephyr ADC API and nrfx SAADC driver API - Nordic Developer Academy

(+) can't send data via ble nus service at high speed and leads to disconnection - Nordic Q&A - Nordic DevZone - Nordic DevZone 

''How much data (how many Bytes) can be sent via IPC so that the transmission does not slow down the rest of the application?''

There is specific fixed rate. It depends on the application. You can read this previous case (+) nRF5340, evaluate options for fast/reliable data transfer method between cores - Nordic Q&A - Nordic DevZone - Nordic DevZone. 

Can cpuapp and cpunet communication via IPC work both ways equally well (cpuapp -> cpunet or cpunet -> cpuapp) ?

Yes.

''Both application and network core send data to each other in the time interval specified by the CONFIG_APP_IPC_SERVICE_SEND_INTERVAL option. You can change the value and observe how the throughput on each core changes.'' source: https://docs.nordicsemi.com/bundle/ncs-latest/page/nrf/samples/ipc/ipc_service/README.html#configuration 

[Kazi Afroza Sultana]

''If I want to establish two-way IPC communication, do I need to add additional mechanisms to avoid errors or data loss?''

I will ask team for details explanation of this query. 

Is the method of sending data via IPC presented in the "ipc_service" sample (extended to send data array from ADC) suitable for my purposes?

yes. 

[Kazi Afroza Sultana]

Hello,

For sending ADC sampling data from App core to netcore is simply you just need to call BLE notification function. If you run the timesync on the netcore, you need to have a way to send that sampling data to BLE application. You need to put the timestamp and the ADC sample together. Most likely in the form of the TIMER counter.