Acorn is a basic autorouter in the context of designing microelectronic silicon chips, packages, and printed circuit boards (PCBs). Written in C, the program reads a user-supplied text file that describes the layout and constraints of the chip/package/PCB, including the start- and end-terminals of wires (nets) that should be routed. For each net, Acorn attempts to find a path from the start-terminal to the end-terminal that does not cross any other nets.
There are many proprietary autorouters that focus on only one part of the microelectronics system, e.g., the silicon chip, or the surrounding package, or the PCB. Acorn is intended to offer an open-source utility for routing across two or all three of these domains.
Acorn was developed and tested in a Linux environment, and requires the user to download and then compile the C source code into the Acorn executable file, acorn.exe. In the directory that contains the makefile, .c and .h files, type the following command from a command-line:
make
For the make command to work, your system must have the GNU Compiler Collection, gcc, and the GNU Make software. The compiler must also have access to the following four libraries: Math (which is included in GCC), OpenMP (also included in GCC), LibPng, and the GD Grapics Library. The latter two libraries can be installed on Red Hat-based Linux distributions using the following commands:
yum -y install libpng-devel
yum -y install gd-devel
Once you've compiled Acorn into the acorn.exe executable, copy this file to a working directory and launch Acorn from the command-line using the following command:
acorn.exe
<input file>> logfile.txt
The <input file> is a text file that describes the silicon chip, package, and/or PCB, in addition to the locations of the start- and end-terminals of each net. There are hundreds of examples of such input files in the tests subdirectory. To get started, try a small example such as 4n_800x_500y_4L_obstacles_wide_vias.txt. In other words, copy this text file to the working directory that contains acorn.exe, and type the following command:
acorn.exe 4n_800x_500y_4L_obstacles_wide_vias.txt > logfile.txt
Depending on how fast your computer is, and how many cores it contains, the program should take a few minutes to complete. (30 seconds with 16 threads is typical.) As it's running, you can monitor two output files: the logfile.txt file (using the less program, for example) and the routingStatus.html file using your favorite web browser. The latter file will be created in the working directory from which you launched Acorn. As a reminder, you can open this file from a browser using CTL-o (or CMD-o on Macs) and navigating to the working directory to open routingStatus.html. The top of this file provides you with the current status, followed by a graph and animated view of the routing. Below the graph is a table that summarizes the results from each iteration. Each row in the table contains a hyperlink to that iteration's routing. Finally, the bottom of the HTML page contains information about the Acorn run, including a link to the input file, design rules, etc.
Incidentally, if you'd like Acorn to use fewer threads than are available on your system, you can use the -t switch to specify the number of threads. For example, if you'd like Acorn to use only 2 threads, invoke Acorn like so:
acorn.exe
-t 24n_800x_500y_4L_obstacles_wide_vias.txt > logfile.txt
Documentation for Acorn is a work-in-progress. Please be patient.