RF switching on STM32L4XX

[Phanirajkiran M]

Posted on April 02, 2018 at 08:01

Hi 

I want to communicate between two STM32L4 MCU, and interfaced RF on to UARTs.

UART1 -- BLE

UART2 -- XBEE

I want to make a transparent, i mean when there is NO BLE there should be a switch to XBee and the other MCU has to be altered to make a seam less communication. When there is enough RSSI for BLE, XBEE and BLE both has to communicate simultaneously in run time.

My queries : 

a. Does the above scenario can happen in run time?

b. If i make a switch in run time will be there any effect on RFs.

I would like to know a better approach to make a RF switch at run time.

Thanks

Phani 

#rssi #xbee #hal-uart #rf #ble

[Andrew Neil]

Posted on April 02, 2018 at 16:13

Phanirajkiran M wrote:

this assignment

Note that the assignment is given to you - therefore you need to be the one doing the research, study, investigation, design, etc.

The Your primary source for assistance should be your teachers or tutors.

We can help where you have specific questions - but theforum is not a place to get your homework done for you!

Phanirajkiran M wrote:

Digi XBEE module

As explained, that is meaningless!

Digi has a

/external-link.jspa?url=https%3A%2F%2Fwww.digi.com%2Fxbee

- so which one, exactly, are you using?

What protocol does it implement?

[Tesla DeLorean]

Posted on April 02, 2018 at 16:15

Start by pulling the RSSI and connectivity metrics from both radios, then have a dispatch loop/buffer which chooses the channels to use based on those metrics. Recognize when you're getting packet loss, and perhaps signal the other end of the connection that you should switch to the more reliable or slower connection.

[Andrew Neil]

Posted on April 02, 2018 at 16:33

So you're not going to bother actually answering the XBee question, then?

But, from your diagram, I guess it must be a WiFi module?

Your flowchart doesn't really make much sense.

Anyhow, there isn't a straightforward, direct relationship between RSSI and distance.

I would suggest that you experiment with each radio separately, and understand each one's behaviour as the link fails, and as it becomes viable again.

You can't just transmit & receive - you will have to establish a 'connection'.

What will you do when neither path is available?

Note that both ends of the link need to be coordinated to know which radio to use

(this is easier with phones, because it's all IP - but that is not your case here).