How to setup the driver & test program to test driver for MCU(i.mx6) and nrf52840 with UART connection.

[LinuxandEmbeddedLearner]

Hi Nordic Support Team,

First sorry for basic questions.

I'm learning the basic hardware setup & Linux driver configuration things to setup & configure the MCU(i.mx6) and nrf52840 with UART connection,

we have one project circuit board (In this board controller MCU(i.mx6) is connected with  nrf52840 using UART).

we are using yocto to setup the Linux things in MCU.

Here is the connection diagram.

I read some couple of threads regarding this setup, got confused with serialization & soft device and HCI.

Please give me some details on this  serialization & soft device and HCI.

How i can add driver to MCU with UART connection  to setup the nrf52840 and test the driver from MCU side.

any defconfig i need to change or any other configuration required from make menuconfig?

Please provide me the steps to do that. Also do i need to do any changes on nrf52840 to communicate with MCU?

Please help Here.

Thanks 

[Einar Thorsrud]

Hi,

Is the case here that you have a Linux MCU which should use the nRF52840 as a BLE connectivity device? If so, it makes sense to run the Bluetooth host on the Linux MCU, and the Bluetooth controller on the nRF52840, and use HCI communication over UART between them. The nRF Connect SDK has read made sample projects that do this. As you want to use UART, you can use Bluetooth: HCI UART. This sample documentation also describes how to use BlueZ as Bluetooth controller on the Linux side.

[LinuxandEmbeddedLearner]

HCI communication over UART between them (MCU & nRF52840)

How and what driver I can add at Linux Host side?

and also what changes  required from Bluetooth controller on the nRF52840 side?

[LinuxandEmbeddedLearner]

Also nRF52840 side we don't have any linux to use BlueZ

[Einar Thorsrud]

You don't need Linux on the nRF52840 side. HCI is a standardized interface that is supported out of the box using BlueZ on Linux (which you have on your host MCU) and by Zephyr, which you run on the nRF52840 when using nRF Connect DSK. So this is a perfect match.

[Einar Thorsrud]

Hi,

LinuxandEmbeddedLearner said:

what changes  required from Bluetooth controller on the nRF52840 side?

On the nRF52840 you can use a sample project which includes a Bluetooth controller and HCI interface. There is a also an example using SPI instead of UART: Bluetooth: HCI SPI. This runs out of the box with a nRF52840 DK. You will need to make some small adjustments to run it on custom HW, at least modify the board file. But over all, the sample is ready for use.

LinuxandEmbeddedLearner said:

How and what driver I can add at Linux Host side?

If you use UART, you can refer to the example documentation for Bluetooth: HCI UART or see the man page for the hciattach  command. which also describe how to configure this on the Linux side. For SPI that is essentially the same on the nRF side (just use the HCI SPI sample instead of HCI UART sample), but on the Linux side it is not as documented nor standardized. I have not been able to find any good documentation describing that, unfortunately.