L2CAP Channel data transfer - ios

Question

I am working on developing BLE app using connection oriented channel . I am using nordic semiconductor nrf52 as a peripheral device and iPhone 6 as central manager.
I have used predefined PSM value provided by Bluetooth SIG that is 0x0025.
I am ble to connect to peripheral and open L2CAP channel successfully.
I am getting below error :
**[CoreBluetooth] WARNING: Unknown error: 436
2018-06-08 10:03:17.532709-0400 BluetoothTest[407:62057] [CoreBluetooth] **No known channel matching peer with psm 37****
Could please let me know how to proceed and what is meaning of error code 436
Below is my code :
func centralManager(_ central: CBCentralManager, didDiscover peripheral: CBPeripheral, advertisementData: [String : Any], rssi RSSI: NSNumber) {
//handling callback when a peripheral is discover
print("Central Manager PowerOn State Check:\(central.state.rawValue)")
if (peripheral.name?.contains("Nordic_OTSX") == true)
{
print(peripheral.name ?? "no name")
print("advertisement Data : \(advertisementData) ")
central.connect(peripheral, options: nil )
myPeripheral = peripheral
}
}
func centralManager(_ central: CBCentralManager, didConnect peripheral: CBPeripheral)
{
print("didConnect\(myPeripheral.debugDescription)")
myPeripheral.delegate = self
myPeripheral.discoverServices(nil)
}
//if error while making connection
func centralManager(_ central: CBCentralManager, didFailToConnect peripheral: CBPeripheral, error: Error?)
{
print("error:\(error.debugDescription)")
}
//after opening L2CAP Channel
func peripheral(_ peripheral: CBPeripheral, didOpen channel: CBL2CAPChannel?, error: Error?)
{
print("didOpen")
print(error.customMirror)
print(channel!.outputStream.debugDescription)
print(channel!.inputStream.debugDescription)
print(channel?.outputStream.hasSpaceAvailable)
}
func peripheral(_ peripheral: CBPeripheral, didDiscoverServices error: Error?)
{
print("*******************************************************")
if ((error) != nil) {
print("Error discovering services: \(error!.localizedDescription)")
return
}
guard let services = peripheral.services else {
return
}
//We need to discover the all characteristic
for service in services {
peripheral.discoverCharacteristics(nil, for: service)
// bleService = service
}
print("Discovered Services: \(services)")
}
func peripheral(_ peripheral: CBPeripheral, didDiscoverCharacteristicsFor service: CBService, error: Error?)
{
print("*******************************************************")
if let charcterstics = service.characteristics
{
print("characteristics :")
for char in charcterstics
{
/* if char.uuid == buttonCharacteristicUUID
{
buttonCharacteristic = char
enableButtonNotifications(buttonCharacteristic!)
readButtonValue()
}*/
print(char.uuid.uuidString)
}
}
peripheral.openL2CAPChannel(0x0025)
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}

Answer 1

I had a similar problem. I manage to solve it by creating a variable to save "channel: CBL2CAPChannel?" in the function
func peripheral(_ peripheral: CBPeripheral, didOpen channel: CBL2CAPChannel?, error: Error?)
I was only saving the "channel.outputStream", which was the only one I needed. But it looks like if you don't save it, it will be closed.

Answer 2

0x25 PSM is for OTS. You need ATT PSM which is 0x1F