Add assignDontCare doc

source/SpinalHDL/Data types/index.rst

@@ -18,6 +18,16 @@ In addition to the base types, Spinal has support under development for:
 * :ref:`Auto-range Fixed-point <afix>` numbers (add,sub,mul support)
 * :ref:`Floating-point <Floating>` numbers (experimental support)
 
+
+Additionaly, if you want to assign a don't care value to some hardware, for instance, to provide a default value, you can use the assignDontCare API to do so. 
+
+
+.. code-block:: scala
+
+   val myBits  = Bits(8 bits)
+   myBits.assignDontCare() // Will assign all the bits to 'x'
+
+
 Finally, a special type is available for checking equality between a BitVector and a bit constant pattern that contains
 holes defined like a bitmask (bit positions not to be compared by the equality expression).
 
@@ -26,7 +36,9 @@ Here is an example to show how you can achieve this (note the use of 'M' prefix)
 .. code-block:: scala
 
    val myBits  = Bits(8 bits)
-   val itMatch = myBits === M"00--10--" // - don't care value
+   val itMatch = myBits === M"00--10--" // - for don't care value
+
+
 
 .. toctree::
    :hidden: 
@@ -39,4 +51,4 @@ Here is an example to show how you can achieve this (note the use of 'M' prefix)
    Vec
    Fix
    Floating
-   AFix
+   AFix