How to rotate the anchors with the rectangle to get better connections

Question

Rectangles when rotated do not rotate anchors. In my code example,

\documentclass[border=2mm]{standalone}
\usepackage    {tikz}
\usepackage    {siunitx} % SI units, \SI and \ang commands    
\usetikzlibrary{babel}   % There are issues with some babel packages
\usetikzlibrary{calc}    % Computing some coordinates 
%
\usetikzlibrary{fadings,decorations.pathreplacing, arrows}
\usetikzlibrary{decorations.markings}
\tikzset{fieldout/.pic={
  \fill circle(0.1);
  \draw [thick] circle(0.25);
  }
}
%----
% To make \rectangle to behave as a \node 
\usetikzlibrary{fit}
\makeatletter
\tikzset{
  fitting node/.style={
    inner sep=0pt,
    fill=none,
    draw=none,
    reset transform,
    fit={(\pgf@pathminx,\pgf@pathminy) (\pgf@pathmaxx,\pgf@pathmaxy)}
  },
  reset transform/.code={\pgftransformreset}
}
\makeatother
%---
\begin{document}
\begin{tikzpicture}[scale=1, 
    every node/.style={font=\Large,  } 
    ]
% some dimensions
\def\hhub{4} % height of I2C hub
\def\whub{2} % width of I2C hub
\def\nconn{4} % num connections in hub
\def\wbeagle{5.5} % width Beagle
\def\hbeagle{9} % height Beagle
\def\lpin{0.14} % side of GPIO square pin
\def\hacc{2} % height of accelerometer detail
\def\wacc{4} % width of  accelerometer detail
% % THE 3 CIRCLE SECTIONS
\begin{scope}[x={(1.5cm,0cm)},y={(0cm,1.5cm)},shift={(0,0)},  thick]
    \foreach[count=\xk] \k in {6.5, 0, -6.5}
    {%
       \draw[dashed, thin,-latex] (-3,\k) -- (4,\k);
       \begin{scope}[shift={(0,\k)}]
           \draw[] (0,0) circle (3);
           \foreach[count=\xi, evaluate={\kk={ifthenelse(\k>-1, \i, \i+60)}}, ]\i in {60,180,300}
           {%
           \begin{scope}[rotate=\kk]
               \draw[gray,dotted] (0,0) -- (3,0);
               \draw[red, opacity=0.85, fill=white,fill opacity=1,] (1.3,-0.27) rectangle (2.3,0.27) node [fitting node] (acc\xk\xi) {};
               \draw[black,semithick] (1.4,-0.23) rectangle (1.6,0.23) ;
               \draw[black,, yshift=1.1cm] (1.4,-0.24) rectangle (1.6,0.24) node[fitting node,] (I\xk\xi) {};
               \foreach[evaluate={\jj={0.46*\j/(\nconn+1) }}] \j in {1, 2,3, 4}
               {
                  \draw[black,fill=black, ] (1.5, -0.23+\jj) circle (0.01); 
                  \draw[black, yshift=1.1cm, semithick] (1.5, -0.23+\jj) circle (0.03); 
               }
              \draw[thin,blue!50, fill=blue!50] (1.8,-0.1) rectangle (2,-0.22)  node[fitting node] (G\xk\xi) {};
           \end{scope}

           }%
      \end{scope}
   }%
   \draw[black,<->,shift={(0,0)},semithick] (-180:0.5) arc (-180:-60:0.5) node [midway,below, xshift=-0.4cm] {\ang{120}}; % ARC 120º
\end{scope}
% The 4 x I2C HUBs
\foreach[count=\cx,  ] \tx/\ty in {1/-6.8,1/0, 1/6.8, 1.75/0}
{%
  \begin{scope}[x={(1cm,0cm)},y={(0cm,1cm)},shift={(-10\tx,\ty)},  thick]
    \draw[black] (-\whub/2,-\hhub/2) rectangle (\whub/2,\hhub/2);
    % \draw[black] (-1cm,-2cm) rectangle (1cm,2cm);
    \foreach[count=\xi, evaluate={\kk={\hhub\i/(\nconn+1) }}, evaluate={\sx={ifthenelse(\i<2,0cm, 2cm ) }},
                                                              evaluate={\sy={ifthenelse(\i<2,-1.25cm, 0cm ) }}] \i in {1,2,3,4} 
    {%
      % into I2C hub with connections
      \draw[black] (-0.75,-\hhub/2+\kk-0.3) rectangle (0.75,-\hhub/2+\kk+0.3) ; 
      \foreach[evaluate={\j={1.5\i/(\nconn+1) }}] \i in {1,2,3,4} % (1.5 = 0.75-(-0.75)) %los punticos
      {%
         \draw[black,fill=black,  ] (-0.75+\j,-\hhub/2+\kk) circle (0.05); 
      }%
      % out I2C hub with connections
      \begin{scope}[xshift=\sx , yshift=\sy]
          \draw[black,] (-0.75,-\hhub/2+\kk-0.225) rectangle (0.75,-\hhub/2+\kk+0.225) node[fitting node] (II\cx\xi) {};
          \foreach[evaluate={\j={1.5\i/(\nconn+1) }}] \i in {1,2,3,4} % (1.5 = 0.75-(-0.75)) %los agujericos
          {%
             \draw[black,semithick,  ] (-0.75+\j,-\hhub/2+\kk) circle (0.075);
           }%
      \end{scope}
    }%
  \end{scope}
}%
% Dimensions of the I2C Hub and text
\begin{scope}[xshift=-17.5cm]
    \draw[black,dashed,] (-\whub/2-0.75, -\hhub/2) --++ (0.75,0); 
    \draw[black,dashed,] (-\whub/2-0.75, \hhub/2) --++ (0.75,0); 
    \draw[black,<->,] (-\whub/2-0.5, -\hhub/2) --++ (0, \hhub) node [midway,above,rotate=90] {\SI{4}{cm}}; % vertical dim line
    \draw[black,dashed,] (-\whub/2, \hhub/2) --++ (0,0.75);
    \draw[black,dashed,] (\whub/2, \hhub/2) --++ (0,0.75);
    \draw[black,<->,] (-\whub/2, \hhub/2+0.5) --++ (\whub,0) node [midway,above] {\SI{2}{cm}};
    \draw[black,latex-,] (-90:-\hhub/2-1.3) -- (0, 5.5) node (T) [above, align=left] {Grove I2C Hub\ACC53133P};
    \draw[black,latex-,] (50:8) -- (T);
\end{scope}
%% -- CONNECTIONS --
\begin{scope}[black,very thick]
    % CONNECTIONS BETWEEN I2C HUBS, AND BEAGLE
    \draw[] (II42.south) --++(0,-9.9) -| (II11.south);
    \draw[] (II43.south) --++(0,-0.175) --++(2,0) --++(0,-3.5) -| (II21.south);
    \draw[] (II44.north) --++(0,2)  -| (II31.south);
% CONNECTIONS BETWEEN I2C HUBS AND ACCELEROMETERS 
% To the TOP Circle
\draw[] (II34.north) |- (I12.west);
\draw[] (II33.north) --++(0,0.15) --++(5.5,0) --++(30:2) -- (I11.south);
\draw[] (II32.north) --++(0,0.15) --++(5.5,0) --++(30:4.7) -- (I13.north);

% To the MIDDLE Circle
% \draw[] (II24.north) --++(0,0.5) -++(5,0) to[out=0,in=-120] (I21.south);
\draw[] (II24.north) --++(0,0.5) -++(7.8,0) -- (I21.south);
\draw[] (II23.north) --++(0,0.15) --++(9,0) -- (I23.north);
\draw[] (II22.south) |- (I22.west);

% To the SOUTH Circle
\draw[] (II14.north) --++(0,0.5) --++(6.75,0) --++(-60:4.37) |- (I33.west);
\draw[] (II13.north) --++(0,0.15) --++(4.5,0) -- (I31.north);
\draw[] (II12.south) --++(0,-0.5)  --++(4.5,0) --++ (-45:5) -- (I32.north);

\end{scope}
%% -- GPIO BLUE LINE CONNECTIONS
\begin{scope}[blue,very thick]
    % Upper Circle section
    \draw[] (G11) --++ (-60:6) node[right] {\sf{P8_42}}; 
    \draw[] (G12) --++ (0,0.5) --++(4.7,0) --++(-60:5.5) node[right] {\sf{P8_46}};
    \draw[] (G13.east) --++ (30:1.5) --++ (-60:4) node[right] {\sf{P8_43}};
    % Middle Circle section
    \draw[] (G21.east) --++ (-30:0.5) --++(-60:5) node[right] {\sf{P8_43}};
    \draw[] (G22.north) --++ (0,0.25) --++(5.1,0) --++(-60:5) node[right] {\sf{P8_35}};
    \draw[] (G23.east) --++ (30:1.6) --++(-60:4) node[right] {\sf{P8_39}};
    % Bottom Circle Section
    \draw[] (G31.east) --++ (30:0.5) --++ (-60:10.7) node[right] {\sf{P8_34}};
    \draw[] (G32.east) --++ (-30:2) --++ (2,0) --++(-60:5) node[right] {\sf{P8_31}};
    \draw[] (G33.south) --++ (0,-1.5) --++(-60:3.8) node[right] {\sf{P8_30}};
\end{scope}
\end{tikzpicture}
\end{document}

The lines that connect the I2C hubs with the rectangles into the circular sections do not join with the middle of the base of those rectangles when they are rotated. I am using the solution in a precedent post How to establish node-anchor-like points on a (tikz) rectangle path....

To have anchors in the rectangles as they were nodes.

The problem of the connection misfit is also in the 'blue' lines that have labels P8_XX at the right.

Answer 1

I can not see what the fitting node is doing for you. You setup complicated \foreach loops to draw nodes with indexed names and then later manually draw lines. I do not think it is worth it. Here I illustrate how you can use \pic to draw repeated elements in your diagram. -obviously you will want to use your own correct polar coordinates.

\documentclass[tikz, border=2mm]{standalone}
\begin{document}
\tikzset{
    myHub/.pic = {
    \draw[fill=white] (-1.25,-0.4) rectangle (1.25,0.4);
    \draw (-0.75,0) circle[radius=0.1] (-0.25,0) circle[radius=0.1] (0.25,0) circle[radius=0.1] (0.75,0) circle[radius=0.1];
    }}
\begin{tikzpicture}[ultra thick]
\draw (0,0) circle[radius=10];
\draw (-20,-5) pic[scale=1.5]{myHub} |- (-4,-3) pic[rotate=90]{myHub};
\draw (-20,-7) pic[scale=1.5]{myHub} |- (-5,-6) -- (-1,-3) -- (0,5) pic[rotate=-30]{myHub};
\draw (-20,-9) pic[scale=1.5]{myHub}  |- (-5,-8) -- (3,-2) -- (5,-3) pic[rotate=30]{myHub};
\end{tikzpicture}
\end{document}