Negative amplitude signals on tikz-timing (Return To Zero)

Question

I'm trying to do RZ with tikz-timing, like in the following picture.

For that I tried using the high impedance timing character Z, like in this MWE :

\documentclass{article}

\usepackage{tikz-timing}

\begin{document}

\begin{center}
    \begin{tikztimingtable}[timing/slope=0, scale=2]
        Horloge      & 8{hl} \\
        01001110     & LHLLHHHL \\
        NRZ          & LHLLHHHL \\
        RZ           & 0.25Z lzh 2{zl} 3{zh} zl 0.25Z \\
      \extracode
        \makeatletter
        \begin{pgfonlayer}{background}
          \vertlines[help lines, blue]{}
          \horlines[blue]{}
          \foreach [count=\x] \b in {0,1,0,0,1,1,1,0} {
            \node [below,font=\sffamily\bfseries\tiny,inner ysep=2pt] at (\x-.5,-1.5) {\b};
          }
        \end{pgfonlayer}
      \end{tikztimingtable}
\end{center}

\end{document}

But it gives this result, where

• The horline is not centered at Z
• Z has a blue color

According to the documentation, the blue color is perfectly normal, as that's how Z works. So I think that I should instead use L as 0 V. Therefore, is there a way to have a negative amplitude with tikz-timing ?

Answer 1

A simple, though somewhat nasty, trick would be to shift the labels and the horizontal lines:

\documentclass{standalone}

\usepackage{tikz-timing}

\begin{document}

\begin{tikztimingtable}[timing/slope=0, scale=2, timing/draw grid, timing/name/.append style={yshift=3.5}, timing/z/.style={black}]
    Horloge      & 8{hl} \\
    01001110     & LHLLHHHL \\
    NRZ          & LHLLHHHL \\
    RZ           & 0.25Z lzh 2{zl} 3{zh} zl 0.25Z \\
    \extracode
    \makeatletter
    \begin{pgfonlayer}{background}
        \vertlines[help lines, blue]{}
        \horlines[blue, yshift=3.5]{}
        \foreach [count=\x] \b in {0,1,0,0,1,1,1,0} {
            \node [below,font=\sffamily\bfseries\tiny,inner ysep=2pt] at (\x-.5,-1.5) {\b};
        }
    \end{pgfonlayer}
\end{tikztimingtable}

\end{document}

Edit: Added code to change z color.

Answer 2

Shift horline.

\horlines[blue,yshift=1.25mm]{}

Set colors for required levels.

\tikzset{
timing/z/.style={color=red},
timing/l/.style={color=red},
timing/h/.style={color=red}
}

\documentclass{article}
\usepackage{tikz-timing}
\tikzset{
timing/z/.style={color=red},
timing/l/.style={color=red},
timing/h/.style={color=red},
timing/slope=0,
timing/name/.append style={yshift=1.25mm}
}

\begin{document}
\begin{center}
    \begin{tikztimingtable}[scale=2]
        Horloge      & 8{hl} \\
        01001110     & LHLLHHHL \\
        NRZ          & LHLLHHHL \\
        RZ           & 0.25Z lzh 2{zl} 3{zh} zl 0.25Z \\
      \extracode
        \makeatletter
        \begin{pgfonlayer}{background}
          \vertlines[help lines, blue]{}
          \horlines[blue,yshift=1.25mm]{}
          \foreach [count=\x] \b in {0,1,0,0,1,1,1,0} {
            \node [below,font=\sffamily\bfseries\tiny,inner ysep=2pt] at (\x-.5,-1.5) {\b};
          }
        \end{pgfonlayer}
      \end{tikztimingtable}
\end{center}
\end{document}