Connecting Pico W to Bluetooth 1.0b phone - RFCOMM

[MatSOBDev]

Maybe that is totally hopeless, but I'm trying to use old brick phone as a GSM feature in DIY embedded stuff. Nothing new, I guess it was possible 20 years ago by UART. It is Sony Ericsson T630. But I'm trying to do it by Bluetooth SPP and getting:

RFCOMM channel open failed, status 0x66

both using sdp_rfcomm_query.c and spp_streamer_client.c examples. They are adapted to connect to right RFCOMM channel. Paining and bonding is possible (seems ok), query responds with available services list, but getting error as above. Connecting to that 1.0b phone's RFCOMM service is also not possible from 4.2 phone (using Android Serial Bluetooth Terminal app).

But there is a plot twist. I have also Sony Ericsson Vivaz (Bluetooth 2.1) and it connects just fine to Pico W (both examples) and 4.2 phone and AT command are up. I get that is quite a difference in Bluetooth versions and backward compatibility might not be enough, in terms of security for example. T630 service is working tho - using Bluetooth terminal app on that 2.1 Vivaz, managed to connect and execute AT commands.

Finally, used a trick of commenting out a linen in cyw43 driver from https://github.com/raspberrypi/pico-sdk/issues/1457 and gap_secure_connections_enable(false);from here https://github.com/bluekitchen/btstack/issues/607 but with no success. Question is, is it so messed up (in a HCI dump) beyond fix? And extra one. In BTstack docs they say RFCOMM will disconnect after 60 seconds of inactivity, but it going strong for hours. Was it modified?

[MatSOBDev]

Here is a HCI dump in *.pklg: https://szybkiplik.pl/32G9kQuECi

[Matthias Ringwald]

Hi

Just back from vacation. Could you post the HCI dump(s) again? The link has expired.

>> In BTstack docs they say RFCOMM will disconnect after 60 seconds of inactivity, but it going strong for hours. Was it modified?

Which 60 seconds timeout? An RFCOMM channel will stay open until one side closes it.

Cheers
Matthias

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[MatSOBDev]

Hi!

So here it is: https://szybkiplik.pl/45b6Jaf24N

I guess it was my misinterpretation: "BTstack will close the multiplexer after 60 seconds without an active RFCOMM channel" from manual.

[Matthias Ringwald]

Hi

Thanks for the log. If you go through it line by line, the issue is that you get error "Unsupported LMP Parameter Value) for 'Set Connection Encryption'