Removed the legacy FMUv4 define that was activating a nonexistent
pull up and on some HW driving the PPM_IN aka RC_IN aka SPEKTRUM_RX
to VDD.
Also detailed the connections of this pins for the board.
The simplest connection is RC_IN to a timer capture pin
and a UART.
In this case the UART_RX pin and just be left as is.
While the pin can be configured as the PPM_IN (Timer capture)
or as SPEKTRUM_RX_AS_GPIO_OUTPUT to use it as and GPIO to
facilitate binding.
Renamed the macros and defines to be more explicit as to what
Is being done and the sense of the parameters
We need to protect access to the param_values array. This is dynamically
allocated and resized (utarray_reserve() calls realloc). If some thread
was iterating the array while another was resizing the array, the first one
would iterate on a freed array, thus accessing invalid memory.
On NuttX this could lead to hardfaults in rare conditions.
Unfortunately we need to initialize the semaphore on startup, by calling
sem_init(). This adds a param_init() method called by every board/config
that uses the params (at least I think I've found all of them)
David Sidrane