\begin{tikzpicture}
[
major/.style={rectangle,draw,rounded corners, thick, align=center, minimum size=20mm},
minor/.style={rectangle,draw,rounded corners, thick, minimum width=40mm, minimum height=15mm}
]

\node (generate-header)[major] {\texttt{generate-header}};
\node (netlist)[major, above=5em of generate-header] {Netlist\\\texttt{foo.net}};
\node (schematic)[major, above=5em of netlist] {Schematic\\\texttt{foo.sch}};
\node (header)[major, below=5em of generate-header] {Header\\\texttt{foo.h}};
\node (template)[major, left=5em of netlist] {Template\\\texttt{my-template}};

\draw [-Straight Barb, thick]
  (schematic.south) -- (netlist.north)
  node[above, midway] {};

\draw [-Straight Barb, thick]
  (netlist.south) -- (generate-header.north)
  node[above, near end] {};

\draw [-Straight Barb, thick]
  (generate-header.south) -- (header.north)
  node[above, midway] {};

\draw [-Straight Barb, thick]
  (template.south) |- (generate-header.west)
  node[above, near end] {};

\end{tikzpicture}