The documentation for IOHIDDeviceCopyValueMultiple is incorrect. I would recommend checking out the header file for IOHIDTransaction.h, it has more information on how transactions work. Output transactions will issue a setReport on the device, while input transactions will issue a getReport on the device.
- Matt > On Dec 6, 2017, at 5:30 PM, James Walker <[email protected]> wrote: > >> On 12/6/2017 4:36 PM, [email protected] wrote: >> Hi James, >> >> IOHIDDeviceCopyValueMultiple will only with with feature/output elements. >> You’ll need to use IOHIDDeviceGetValue if you're querying input elements. > > The documentation for IOHIDDeviceCopyValueMultiple says " This method behaves > synchronously and return back immediately for input type element." Doesn't > that imply that it should work for input elements? > > Also, transactions don't seem to work for me either, and > IOHIDTransactionCreate has a "direction" parameter. > >> >> —scott >> >>> On Dec 1, 2017, at 5:43 PM, James Walker <[email protected]> wrote: >>> >>> Another problem I'm having with the HID functions is that >>> IOHIDDeviceCopyValueMultiple always returns kIOReturnError. I can use >>> IOHIDDeviceGetValue successfully, but IOHIDDeviceCopyValueMultiple is >>> supposed to be more efficient if you want to get a bunch of values at once. >>> >>> I downloaded some IOKit source code and found that the kIOReturnError error >>> is being returned by a call to IOHIDTransactionCommit internal to >>> IOHIDDeviceCopyValueMultiple, but that doesn't clear things up. > > _______________________________________________ > Do not post admin requests to the list. They will be ignored. > Usb mailing list ([email protected]) > Help/Unsubscribe/Update your Subscription: > https://lists.apple.com/mailman/options/usb/dekom%40apple.com > > This email sent to [email protected]
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