Skip to content

USB device communication

Jump to bottom
Artem edited this page Mar 9, 2018 · 1 revision

Create USBDeviceMonitor object globally, set vid and pid of devices that you need to listen and run monitor in new thread for listen USB devices


import Cocoa
import USBDeviceSwift

@NSApplicationMain
class AppDelegate: NSObject, NSApplicationDelegate {
    //make sure that stm32DeviceMonitor always exist
    let stm32DeviceMonitor = USBDeviceMonitor([
        VIDPID(vendorId: 0x0483, productId: 0xdf11)
    ])

    func applicationDidFinishLaunching(_ aNotification: Notification) {
        // Insert code here to initialize your application
        let stm32DeviceDaemon = Thread(target: stm32DeviceMonitor, selector:#selector(stm32DeviceMonitor.start), object: nil)
        stm32DeviceDaemon.start()
    }
}

note - start function using RunLoop that blocks thread don't run monitor in Main thread

There are two global notifications:

USBDeviceConnected

USBDeviceDisconnected

Listen them in our ViewController:

class ViewController: NSViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view.

        NotificationCenter.default.addObserver(self, selector: #selector(self.usbConnected), name: .USBDeviceConnected, object: nil)
        NotificationCenter.default.addObserver(self, selector: #selector(self.usbDisconnected), name: .USBDeviceDisconnected, object: nil)
    }

    // getting connected device data
    func usbConnected(notification: NSNotification) {
         guard let nobj = notification.object as? NSDictionary else {
             return
         }

         guard let deviceInfo:USBDevice = nobj["device"] as? USBDevice else {
             return
         }
    }

    // getting disconnected device id
    func usbDisconnected(notification: NSNotification) {
         guard let nobj = notification.object as? NSDictionary else {
             return
         }

        guard let deviceInfo:USBDevice = nobj["id"] as? UInt64 else {
            return
        }
    }
}

USBDeviceConnected notification - returns USBDevice with all basic info

USBDeviceDisconnected notification - returns id from IORegistryEntryGetRegistryEntryID

Send command to USB device example:

enum STM32DeviceError: Error {
    case DeviceInterfaceNotFound
    case InvalidData(desc:String)
    case RequestError(desc:String)
}

func getStatus() throws -> [UInt8] {
    //Getting device interface from our pointer
    guard let deviceInterface = self.deviceInfo.deviceInterfacePtrPtr?.pointee?.pointee else {
        throw STM32DeviceError.DeviceInterfaceNotFound
    }

    var kr:Int32 = 0
    let length:Int = 6
    var requestPtr:[UInt8] = [UInt8](repeating: 0, count: length)
    // Creating request
    var request = IOUSBDevRequest(bmRequestType: 161,
                                  bRequest: 0x03,
                                  wValue: 0,
                                  wIndex: 0,
                                  wLength: UInt16(length),
                                  pData: &requestPtr,
                                  wLenDone: 255)

    kr = deviceInterface.DeviceRequest(self.deviceInfo.deviceInterfacePtrPtr, &request)

    if (kr != kIOReturnSuccess) {
        throw STM32DeviceError.RequestError(desc: "Get device status request error: \(kr)")
    }

    // Getting our data
    return requestPtr
}

See full example in STM32DeviceExample folder

Clone this wiki locally