@Max-Peng
At least you got something to work. I've been fighting this SPI thing for weeks, on and off. There seems to be no way to do SPI from a C program, and no good way to develop anything in C due to lack of kernel repo or at least config. I'm binning my three Omega2+s, without SPI they're useless to me. A pity, I like these things but without access to the stuff I need there's no point.

I have seen discussions about your problem with the first byte being corrupted, in the forum here but there doesn't seem to any resolution.