Thanks Craig,
I carefully studied BTC demo for 21369 and now BTC works in my application.
The differences with the quoted description are:
1. I do not use btc_poll() - just update BTC channels data with interesting variables values.
2. Please, mention that channel definitions are global and initialisation should be done in main().
3. BTC channels data must be defined as externals in files we use them.
That's all.
Best regards
Roman
P.S. I am not experienced C programmer, as prefer assembler in real-time systems, where every saved clock cycle counts.