I have a STM32F303 acting as a serial port to an industrial control system, but I need a reliable way to set a byte for out-of-band data (I need to set "termination resistor On/Off, Drive Strength, etc -- I'm using the "comm port" for the serial data, but I need to set the interface bits)... it seems Windows is doing a good job of thwarting me:
I tried changing the UBCDdevice... but windows only reads it at plug-in time (even if I do IOCTL on the hub to read the descriptor again).
I tried returning the info in the upper byte of dwBaudRate in the LineCoding, but it seems that Windows does some odd combination of reading/writing to it so the data doesn't pass cleanly through...
What's the best way to handle this kind of out-of-band-data? Is there a good, simple way to get a "byte" back (like RI, CD, DSR, CTS, Foo, bar, baz, squack) using the CDC, or should I make the device show up as 2 com ports (1 for normal communication, one for line status/configuration) -- I only need 1 byte in and one byte out at "config time" (but they must be independent -- I'll send "NoTemination, Invert, Pace", and I want to get back "NoiseLevel0-4, 0-15devices, commgood," not "I'll Read LineCoding, and I'll only write the delta and you're nuts if you think 4MBaud is ok"), but Windows seems to be thwarting me every step of the way...
