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K20 Generator Control in FreeMaster (KM34Z50M_GEN on TWR-KM34Z50M)

Question asked by Mark Butcher on Dec 7, 2014
Latest reply on May 28, 2016 by Mark Butcher

Hi All


I am presently working with the TWR-KM34Z50M and need to do something similar to the K20 based Generator which can be controlled by FreeMaster via USB (see manual chapter 6.6)


Since there are some strange things going on with the version that is pre-installed on the board I took a closer look and found that the USB device (called KM34Z50M_GEN) may be doing something wrong whenever it sends what looks to be a badly formed SERIAL_STATE (?)

There are 10 bytes of data sent on the INTERRUPT pipe (endpoint 3) which change between

0x00 0x00 0x00 0x00 0x00 0x00 0x02 0x00 0x00 0x00


0x00 0x00 0x00 0x00 0x00 0x00 0x02 0x00 0x03 0x00

If this is a SERIAL_STATE notification the first byte should be 0xa1 (and not 0x00) and the second byte 0x20 (and not 0x00).

It could also be an incorrectly formed NETWORK_CONNECTION (which matches the second byte, bNotification) but then the rest makes even less sense.


I believe that this is a CDC class notification and has nothing to do with the FreeMaster protocol itself, and therefore is also not discussed in any FreeMaster documentation.

Is this a bug in the KM34Z50M_GEN and can it be a cause of difficulties?






P.S: On a side note - I didn't manage to find a driver for the USB device (TWR_KM34Z50M_K20_Gen.inf according to the TWR-KM34Z50M manual) so I modified an existing CDC driver .inf to match and that seemed to sort it out. Although I searched through various SW packages without success beforehand .. does it actually exist and has it therefore been used before?