Resolve Rule 5-0-6: cast to 7 bits struct field

[misra cpp]

The way bit-fields should be handled is described on page 53 of MISRA C++ 2008

It is possible that the problem is caused by the "& 0xFFU" which gives a value in the range 0..255 (i.e. 8 bit) which is assigned to a 7 bit field

Try using & 0x7FU which gives a value in the range 0..127, i.e. 7 bit. It's also possible that the static_cast to a 32-bit type is the cause of the problem