tikz register map

Question

I whant to draw register description like in the picture, but my tikz knowlage is very poor. Any startups?

Answer 1

This answer comes with a style register that does most of the work for you. It draws the frame, left aligns the cells using the eqparbox package, and draws the horizontal and vertical cell dividers.

\documentclass[tikz,border=3mm]{standalone}
\usetikzlibrary{matrix}
\usepackage{eqparbox}
\newbox\matrixcellbox
\tikzset{l column/.style={execute at begin
node={\setbox\matrixcellbox=\hbox\bgroup},
execute at end
node={\egroup\eqmakebox[\tikzmatrixname\the\pgfmatrixcurrentcolumn][l]{\copy\matrixcellbox}}},
register/.style={matrix of nodes,nodes={l column},draw,rounded corners,column sep=0pt,
execute at end matrix={%
\path (\tikzmatrixname-1-1.south) -- (\tikzmatrixname-2-1.north) 
    coordinate[midway](tmpH)
    (\tikzmatrixname-1-\the\numexpr\pgfmatrixcurrentcolumn-1\relax.east) 
    -- (\tikzmatrixname-1-\the\pgfmatrixcurrentcolumn.west) 
    coordinate[midway](tmpV);
\draw (\tikzmatrixname.west|-tmpH) -- (\tikzmatrixname.east|-tmpH)  
(\tikzmatrixname.north-|tmpV) -- (\tikzmatrixname.south-|tmpV);
}}}
\begin{document}
\begin{tikzpicture}[font=\sffamily]
 \matrix[register](reg1){
  L2 & L0 & NOISE MODE\\
  0 & 0 & LOW NOISE MODE\\
  0 & 1 & RESERVED\\
  1 & 0 & RESERVED\\
 };
\end{tikzpicture}
\end{document}

As you can see, you only need to provide the contents. This can be used for your graph as follows:

\documentclass[tikz,border=3mm]{standalone}
\usetikzlibrary{matrix,positioning,decorations.pathreplacing,fit,backgrounds}
\usepackage{eqparbox}
\newbox\matrixcellbox
\tikzset{l column/.style={execute at begin
node={\setbox\matrixcellbox=\hbox\bgroup},
execute at end
node={\egroup\eqmakebox[\tikzmatrixname\the\pgfmatrixcurrentcolumn][l]{\copy\matrixcellbox}}},
register/.style={matrix of nodes,nodes={l column},draw,rounded corners,column sep=0pt,
execute at end matrix={%
\path (\tikzmatrixname-1-1.south) -- (\tikzmatrixname-2-1.north) 
    coordinate[midway](tmpH)
    (\tikzmatrixname-1-\the\numexpr\pgfmatrixcurrentcolumn-1\relax.east) 
    -- (\tikzmatrixname-1-\the\pgfmatrixcurrentcolumn.west) 
    coordinate[midway](tmpV);
\draw (\tikzmatrixname.west|-tmpH) -- (\tikzmatrixname.east|-tmpH)  
(\tikzmatrixname.north-|tmpV) -- (\tikzmatrixname.south-|tmpV);
}}}
\begin{document}
\begin{tikzpicture}[font=\sffamily]
 \begin{scope}[local bounding box=BM]
  \matrix[matrix of nodes,column sep=0.5ex,
  execute at end matrix=\xdef\NumCols{\the\pgfmatrixcurrentcolumn}] (bigm) {%
   PFT & PFT & PFT & PFT & PFT & PFT & DB2 & DB1 & DB0\\
   0 & L2 & L1 & M3 & M2 & M1 & C3(0) & C2(1) & C1(0)\\
  };
  \node[anchor=west,rotate=90] at (bigm-1-1.north){RESERVED};
  \path (bigm-1-2.north) -- (bigm-1-3.north) node[midway,above,align=center]
  {LOW\\ NOISE AND\\ LOW SPUR\\ MODES};
  \path (bigm-1-4.north) -- (bigm-1-6.north) node[midway,above,align=center]
  {MIXOUT};  
 \end{scope}
 %
 \begin{scope}[on background layer]
 \node[fit=(BM),draw,rounded corners,inner sep=0pt,yshift=2pt,
  path picture={\fill[gray!20,sharp corners] (bigm-2-7.west|-BM.south) rectangle
  ([yshift=3pt]BM.north east);}](F) {};
  \foreach \X [count=\Y] in {2,...,\NumCols}
  {\path (bigm-1-\Y.east) -- (bigm-1-\X.west) coordinate[midway] (aux);
  \draw (F.south-|aux) -- (bigm-1-1.north-|aux); }
  \foreach \X in {1,2}
  {\draw (F.west|-bigm-\X-1.north) -- (F.east|-bigm-\X-1.north);}
 \end{scope}
 %
 \matrix[register,below=2cm of bigm.south west,xshift=1cm](reg1){
  L2 & L0 & NOISE MODE\\
  0 & 0 & LOW NOISE MODE\\
  0 & 1 & RESERVED\\
  1 & 0 & RESERVED\\
 };
 \draw[decorate,decoration=brace,thick] (bigm-1-3.east|-F.south)
  -- (bigm-1-2.west|-F.south) coordinate[midway,below=2pt] (b1);
 \draw[-stealth] (b1) -- (b1|-reg1.north);
\end{tikzpicture}
\end{document}

This is a starting point that illustrates how one can get these tabulars in nodes, how to position them relative to each other and how to draw the braces and arrows. The rest is mainly repetition.

OLDER ANSWER: (ugly point: manual fixing of the horizontal positions of the brace.)

\documentclass[tikz,border=3mm]{standalone}
\usepackage{bigstrut}
\usetikzlibrary{positioning,decorations.pathreplacing}
\begin{document}
\begin{tikzpicture}[font=\sffamily]
 \node[draw,rounded corners,inner sep=0pt](bigm) 
 {\begin{tabular}{*6{c|}}
  \rotatebox[origin=c]{90}{RESERVED~} & \multicolumn{2}{c}{\begin{tabular}{c}
   LOW\bigstrut[t]\\ NOISE AND\\ LOW SPUR\\ MODES
  \end{tabular}} & \multicolumn{3}{c}{BLABLA}\\
  \hline
  PFT & PFT & PFT & PFT & PFT & PFT \\
  0 & L2 & L1 & M3 & M2 & M1\\
 \end{tabular}};
 %
 \node[draw,rounded corners,inner sep=0pt,below=2cm of bigm.south
 west,xshift=1cm] (st1){%
  \begin{tabular}{ll|l}
  L2\bigstrut[t] & L0 & NOISE MODE\\
  \hline
  0 & 0 & LOW NOISE MODE\\
  0 & 1 & RESERVED\\
  1 & 0 & RESERVED\\
 \end{tabular}};
 %
 \draw[decorate,decoration=brace,thick] ([xshift=2.18cm]bigm.south west)
  -- ([xshift=1.1cm]bigm.south west) coordinate[midway,below=2pt] (b1);
 \draw[-stealth] (b1) -- (b1|-st1.north);
\end{tikzpicture}
\end{document}