Thank you for answer and hint. This example was a template for my code :). But I want to send just 8 bit value from potentiometer. It is clearly receiving, because I am sending it on pushed button and it shows something.
I tried to send four values as well, but there were different numbers.
In that example - in case I would like to send value PINGa, PINGb or PINGc and read last character would it be something like this?
if (strncmp((char *) rx_buffer, "PING", bc_spirit1_get_rx_length()) == 0)
{
bc_log_debug(rx_buffer[5]);
}