openL2CAPChannel fails on iOS - same code works on macOS

RE: openL2CAPChannel fails on iOS - same code works on macOS

Torsten Robitzki — Thu, 30 Apr 2020 15:55:08 GMT

denis have you managed to solve that problem? I'm hitting the same Problem.

Looks like following the spec and just to use PSM in the range of 0x0080 to 0x00FF (see CoreSpec Vol3; Part A, 4.22 Table 4.19) fixes the problem.

RE: openL2CAPChannel fails on iOS - same code works on macOS

Juju — Mon, 19 Nov 2018 20:21:32 GMT

Ah ok, I thought it was the problem because in my case it removed the warnings you are having when I did that with PSM=0x025.

However, when using PSM=0x1001 and calling openChannel from iOS, it seems to not even issue a L2CAP channel request to the NRF board. Seems blocked by Core Bluetooth as an invalid PSM value.

RE: openL2CAPChannel fails on iOS - same code works on macOS

denis — Mon, 19 Nov 2018 17:42:23 GMT

Hi Juju,

I'm keeping a strong reference, so don't think that is the issue here. Also - works consistently with a predefined PSM, just not with the PSM I want to use.

RE: openL2CAPChannel fails on iOS - same code works on macOS

Juju — Mon, 19 Nov 2018 17:32:18 GMT

Hi Denis

I was just having the same problem as you because on iOS side, I was not keeping a strong reference to

the CBL2CAPChannel object given by:

- (void)peripheral:(CBPeripheral *)peripheral didOpenL2CAPChannel:(CBL2CAPChannel *)channel error:(NSError *)error

Now I will try to send/receive data from it...

Found the trick here: stackoverflow.com/.../52239966

RE: openL2CAPChannel fails on iOS - same code works on macOS

denis — Mon, 12 Nov 2018 14:36:22 GMT

I'm using the latest nRF5 SDK 15.2.0.

RE: openL2CAPChannel fails on iOS - same code works on macOS

haakonsh — Mon, 12 Nov 2018 08:20:19 GMT

Hey Denis,

I need to compile your project, what SDK are you using?

Cheers,

RE: openL2CAPChannel fails on iOS - same code works on macOS

denis — Wed, 07 Nov 2018 17:33:04 GMT

If I change the PSM from 0x1001 to 0x25 then iOS does open the connection, but also issues some warnings:

2018-11-07 11:27:01.654639-0600 Simple Bluetooth iOS[13373:9843832] didOpenL2CAPChannel Optional(<CBL2CAPChannel: 0x28336c4b0 peer = <CBPeripheral: 0x280c24820, identifier = 5DEE8C89-16AF-356F-A0CA-B3C7D810E4E3, name = Firefly, state = connected>, psm = 37>) error: nil

2018-11-07 11:27:01.681656-0600 Simple Bluetooth iOS[13373:9843832] [CoreBluetooth] WARNING: Unknown error: 436

2018-11-07 11:27:01.682131-0600 Simple Bluetooth iOS[13373:9843832] [CoreBluetooth] No known channel matching peer <CBPeripheral: 0x280c24820, identifier = 5DEE8C89-16AF-356F-A0CA-B3C7D810E4E3, name = Firefly, state = connected> with psm 37