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blhost under OS X: cannot open USB HID device

Question asked by Robert Poor on Apr 20, 2017
Latest reply on Apr 20, 2017 by Robert Poor

I'd like to reflash my KL27Z using its resident ROM bootloader with the blhost command-line tool running under OS X.


I understand that the blhost -u command requires a vendor id and product id.  I used the OS X system_profiler command to discover that:


$ system_profiler SPUSBDataType



    USB 3.0 Bus:


      Host Controller Driver: AppleUSBXHCILPTH

      PCI Device ID: 0x8c31

      PCI Revision ID: 0x0005

      PCI Vendor ID: 0x8086


        Apple Internal Keyboard / Trackpad:



        OpenSDA Hardware:


          Product ID: 0x0089

          Vendor ID: 0x1357

          Version: 8.00

          Serial Number: SDA597D4E7F

          Speed: Up to 12 Mb/sec

          Manufacturer: P&E Microcomputer Systems Inc.

          Location ID: 0x14200000 / 12

          Current Available (mA): 500

          Current Required (mA): 464

          Extra Operating Current (mA): 0


Based on the above, I believe the vendor ID is is 0x1357 and the product ID is 0x0089.  But blhost complained:

$ blhost -u 0x1357,0x0089 -- get-property 1
Error: UsbHidPeripheral() cannot open USB HID device (vid=0x1357, pid=0x0089, sn=).Roberts-MacBook

I unmounted the FRDM-KL27Z filesystem and -- as far as I can tell -- no other application is accessing that USB port.  Any suggestions on what to try next?