Hi all,
Hope someone can help, I've asked this question on the microchip site but not got a straight answer

In the past I used a rn42 module configured as a master, auto connect.

I used it to send serial data to a Bluetooth printer and a 3rd party android app.

As I understand it that's over SSP on Bluetooth 2.1?

I've recently bought some bm78 modules which are dual-ssp, the documentation is really bad but I have got it talking to a couple of Bluetooth serial apps, (not the one I want however. I've also started fiddling with the configuration of the module but still can't get it to talk to my printer or app?

The bm78 module is Bluetooth 3 & 4, I thought it should be backward compatible but have wasted/invested a lot of time on these modules, is there a chance it will work?

Cheers Geoff

 

That isnt easy to say...
Given that any link has at least two ends you will have to quantify and undertstand both.

My only experience of Bluetooth is in devices and even that is a pain.
I think the problem extends from Bluetooth being an extensible standard which means that the core may be backwardly compatible but there is no guarantee that the implimentations are.

My new phone for example will not put media audio onto the mono interface so my car kit didnt work...
Fixed, mostly, with an app but none the less a pain and the fact that there is an app, well because it doesn't work as expected.
I have audio now but not voice commands or extended button functionality.

You are going to need a handle on exactly what is talking to what and how, to have any chance of fixing the problem.

Sorry that isnt better news, but it is likely that others have had the issue so a bit if studious searching may help.

It would be well worth checking your device interfaces, for setting options and update possibilities...
New board, old device, one of then needs bend.

Al

 

Thanks,
The module will have to do the bending!
I've had a useful reply from a microchip member who says the bm78 doesn't support master mode....
However the rn 4678 which is the same hardware with a ASCII interface does?
I've got one of those, will let you know how I get on!
Cheers Geoff

 

Hi all,
A thread with no answer is useless , so here it is...

The bm78 doesn't support master mode as you can't ask it to do a inquiry scan, if you want a transparent UART to most Android phone apps its fine, you can change the RFCOMM channel with the ui tool or via UART and terminal but its a bit tricky to suss.

The rn 4678 is the same module with different firmware that is controlled with a set of ASCII commands, it can do a inquiry scan and connect as a master, so works with my printer.
The app on my phone seems to need RFCOMM channel 1, default is 0. There isn't a ASCII command to change RFCOMM channel but you can write to eeprom, if you know what value to write to which address. You need the ui tool for the bm78 to create a map and compare it to the default map...... Its not easy but does work!
All this maybe no interest to anyone tho
Cheers Geoff