Russ, what is that doing? It does work using Andy's code with a simple return of your value....is the HexValue a passed array member that is compared?

Here is that function block in application and tested:

unsigned char Hex2Ascii(unsigned char HexValue)
{
   // First, ensure that the value to be converted  is in the low nibble
   if( HexValue > 0x0F )
   {
      HexValue >>= 4; // Shift the value down from the top nibble
   }
   return "0123456789ABCDEF"[HexValue];

}