Reading and writing to USB (HID) interrupt endpoints on Mac

Question

I am attempting to communicate with a rather specific USB device and developing both Windows and Mac code to do so.

The device is a USB device with a HID interface

Answer 1

I ran into this same kIOReturnExclusiveAccess. Instead of fighting it (building a kext, etc). I found the device and used the POSIX api's.

//My funcation was named differently, but I'm using this for continuity..
void DemiUSBDevice::device_attach_callback(void * context, 
    io_iterator_t iterator)
{
DeviceManager *deviceManager = (__bridge DADeviceManager *)context;
  io_registry_entry_t device;
  while ((device = IOIteratorNext(iterator))) {

    CFTypeRef prop;
    prop = IORegistryEntrySearchCFProperty(device,
                                           kIOServicePlane,
                                           CFSTR(kIODialinDeviceKey),
                                           kCFAllocatorDefault,
                                           kIORegistryIterateRecursively);
    if(prop){
      deviceManager->devPath = (__bridge NSString *)prop;
      [deviceManager performSelector:@selector(openDevice)];
    }
  }
}

once devPath is set you can call open and read/write..

int dfd;
dfd = open([devPath UTF8String], O_RDWR | O_NOCTTY | O_NDELAY);
  if (dfd == -1) {
    //Could not open the port.
    NSLog(@"open_port: Unable to open %@", devPath);
    return;
  } else {
    fcntl(fd, F_SETFL, 0);
  }