doc: Add unofficial support for HiFiBerry Amp2

This board is suitable to connect passive speakers to an unofficial
soundbox build.

1 files changed, 33 insertions, 16 deletions

diff --git a/doc/documentation.tex b/doc/documentation.tex
index 23e1c2b..b605e58 100644
--- a/doc/documentation.tex
+++ b/doc/documentation.tex
@@ -5,19 +5,16 @@
 
 \usepackage{graphicx}
 \graphicspath{ {./diagrams/} }
+\usepackage{array}
 \usepackage{hyperref}
 \usepackage{parskip}
 
 \begin{document}
 
 \maketitle
-\newpage
-
 \tableofcontents
-\newpage
-
 \listoffigures
-\newpage
+\listoftables
 
 \chapter{Introduction}
 \label{chap:introduction}
@@ -305,23 +302,42 @@ can be achieved with \texttt{addgroup}.
 addgroup root audio
 \end{verbatim}
 
-soundbox uses the HiFiBerry shield to output high-quality audio. This shield
-needs to be enabled as an audio output by specifying a Devicetree overlay in
-the Raspberry Pi configuration file with \texttt{echo}. Since this file is
-stored on the SD card only which is mounted as read-only it has to be remounted
-with the read-write option first.
+soundbox uses the HiFiBerry DAC+ Zero shield to output high-quality audio. This
+shield needs to be enabled as an audio output by specifying a Devicetree
+overlay in the Raspberry Pi configuration file with \texttt{echo}. Since this
+file is stored on the SD card only which is mounted as read-only it has to be
+remounted with the read-write option first.
 
 \begin{verbatim}
 mount -o remount,rw /media/mmcblk0p1
 echo 'dtoverlay=hifiberry-dac' >> /media/mmcblk0p1/config.txt
 \end{verbatim}
 
-If the builtin audio of e.g. a Raspberry Pi 4 should be used another Devicetree
-option has to be inserted instead:
-
-\begin{verbatim}
-echo 'dtparam=audio=on' >> /media/mmcblk0p1/config.txt
-\end{verbatim}
+Only the HiFiBerry DAC+ Zero is officially supported for soundbox. Nevertheless
+\autoref{hardware-variants-table} shows the configuration line for other
+hardware.
+
+\begin{table}[h]
+\begin{center}
+\begin{tabular}{ | l | l | l | }
+\hline
+	Audio hardware & Config line & Support \\
+\hline
+\hline
+	HiFiBerry DAC+ Zero & \texttt{dtoverlay=hifiberry-dac} & official \\
+\hline
+	HiFiBerry Amp2 & \texttt{dtoverlay=hifiberry-dacplus} & unofficial \\
+\hline
+	Raspberry Pi 4 audio & \texttt{dtparam=audio=on} & unofficial \\
+\hline
+\end{tabular}
+\end{center}
+\caption{Audio settings for soundbox variants}
+\label{hardware-variants-table}
+\end{table}
+
+It has to be noted that the unofficially supported hardware does not fit into
+the \texttt{soundbox} case.
 
 \subsection{soundbox script}
 
@@ -443,6 +459,7 @@ Versioning\footnote{\href{https://semver.org/spec/v2.0.0.html}{https://semver.or
 
 \begin{itemize}
 	\item device label containing project name, version and MAC address
+	\item unofficial support for HiFiBerry Amp2
 \end{itemize}
 
 \subsection{Changed}