BLE UART/SPI

[agus.uy]

Hello all,

I'm working on updating bluetooth communication. Currently using a module that receives AT style commands.

The first step will be replacing with nordic device, then change HW and include the code into the SoC.

I have a nRF52 DK, but all the examples are meant to program directly on the nRF52.

Does anyone know if there is a FW I can use that will allow using the nRF52 as a similar module through SPI or UART? Or is the nRF52 a bad choice here?

Thanks for any help you can provide

[awneil]

You mean, you want the nRF52 to act like a BLE "modem" - controlled by AT commands?

[agus.uy]

Basically, yes. Not necessarily AT commands, but yes.

After having a working hardware I'll start moving code to the nRF52

[haakonsh]

"But it remains unclear to me what the OP is actually trying to achieve."

Yeah we need some more information :)

[agus.uy]

Hello,

I'm first trying to have a solution with an application MCU with all my code, and a nRF for BLE connectivity with a FW I don't have to change (ideally just flash a code from nordic). After that is working I can advance other parts of the design both HW and application FW.

I'll eventually start moving code to the nRF but not now.

[haakonsh]

Well, since your end goal is to keep the BLE application on the nRF52 I think you should consider not to use serialization as you will save a lot of development time in the long run. To use the serialization library you need to port a lot of our drivers and libraries to your host MCU.

What exactly are your BLE needs? 

[awneil]

I think I agree. (though still not entirely clear)

Rather that try to do this hybrid half-way-house mash-up, I think it may be easier to just treat this as a new development.

ie, start on nRF with some basic BLE functionality, and bring in stuff from your "main" app ...

[agus.uy]

My BLE needs are very low power and security. It will not advertise unless instructed and ideally it will be completely silent except during communication.

The device needs to receive configuration and answer to commands from a PC/Tablet or phone, this just a few times a day. Data is just plain data, so the Nordic UART over BLE is a good fit to start with.

A version of the application is already running with a BT 2 module, using serial cable emulation, with no security and high power, with AT style control.

I'd like to substitute the module with a nRF. Initially I want to use it as is, if possible not writing code for it (using an existing FW from nordic) and controlling BLE through SPI or UART. I don't mind porting some libraries to do this, but it would certainly help if they are already made.

After this solution is working the next step will be shifting the comms processing entirely to the nRF, but that will be a separate effort. I don't think I'll be able to move all my application to the nRF due to timing, I/O and peripheral requirements.

[haakonsh]

The UART/Serial Port Emulation over BLE example is definitely the way to go in your case. I would forget the serialization library as it is not suited for your use-case. 

Once you have the UART over BLE communication up and running you can offload other tasks from the main MCU if you want to. 

[agus.uy]

OK,

I'm starting from the UART, I'll just change how to connect (security, power)

Is there a way to have some control of the BLE from the application MCU? Because if I understand correctly I have only the UART that goes through.

[awneil]

Yes - you write yourself some sort of UART-based API.

AT Commands is a common example (as initially mentioned) - but you can make up your own protocol to suit your specific needs ... 

EDIT

See: https://devzone.nordicsemi.com/f/nordic-q-a/39029/ble-uart-spi/151049#151049

(the way this forum shuffles posts makes it hard to find specific replies - took me a while to find that!)

[agus.uy]

I get the idea, to add a layer between the MCU and nRF exposing what I need. I'll work on it.

The link takes me to this same post...

[awneil]

It's the post of 1 Oct at 17:05 - 

awneil said:

The SoftDevice is the BLE Stack - the code you write can do the comms with the rest of your system.