Overview
The scripts pcb-matrix and sch-matrix replicate PCB and schematic
structures by copying an input file to an output file multiple times
incrementing the (x,y) position of each copy. The copied
structures are arranged in a matrix as specified in a configuration
file.
N.B. These scripts may not work for all layouts. I wrote
sufficient code to copy the schematic and PCB elements for one of my
designs not for all possible designs. I am almost certain that
sch-matrix will break for schematics with embedded
symbols.
Conventions
| parameter | Replace with the value of parameter
|
verbatim text | Verbatim text when associated with a command or contents of a file.
|
sch-matrix | The current version of the schematic matrix program.
|
pcb-matrix | The current version of the PCB matrix program.
|
sch-matrix_version | Version version of the schematic matrix program.
|
pcb-matrix_version | Version version of the PCB matrix program.
|
Creating a Design
To create a design:
- create an input schematic
Create a schematic that contains the structure to be replicated.
- create an input PCB
run
gschpcb on the input schematic and create a PCB
layout (which will be the input PCB layout).
- add the marker line to the input PCB
using your favorite editor (EMACS)
add the marker line to the input PCB.
- create configuration files
create configuration files for
sch-matrix and pcb-matrix.
- create an output schematic run
sch-matrix
- create an output PCB run
pcb-matrix
If all of the reference designators are assigned in the input
schematic and that schematic is used to create the input PCB file then
all of the reference designators in the output schematics and PCB
files will be in-sync.
sch-matrix and
pcb-matrix use the same algorithm to update reference
designators.
sch-matrix
Usage
sch-matrix_0 <configuration filename>
Description
The
sch-matrix script creates a new layout by coping each
component,
text value,
net,
line and
circle to an output file multiple
times. Each structure is positioned as defined by the parameters in
the configuration file. For each
component the reference
designator is updated to maintain unique reference designators in the
output file.
Creating the Schematic
Schematics are created in the usual manner using
gschem. Prior to running
sch-matrix all of
the reference designators (refdes's) must be
assigned.
sch-matrix dies if the refdes does not match an
alphabetic string followed by integer (
which is the regular
expression [A-Za-z]+\d+).
Connecting the Replicated Schematics
The replicated schematics can be connected by naming nets or by
placing nets so that they will physically connect after replication.
Naming the nets produces less clutter on the schematic but does not
show connectivity. Using continous nets shows connectivity but can be
messy when there are many nets or nets in many directions (such as
when groups of components are arranged in a matrix).
If the groups are all in a row (or all in a column) then a continous
horizontal (or vertical) net can be placed. By choosing the
appropriate length for the net and the proper
xoffset and
yoffset a single continous net will be created in the
output file. For a matrix a combination of net names and continuous
nets may be best.
Adding Circuitry to the Output Schematic
Usually additionaly circuitry will need to be added to the output
schematic to complet a design. However, everytime
sch-matrix is run the output schematic is overwritten. If
you embed the output schematic in your design using a heirachical
block then this problem is eliminated. Since connections to the block
are by net names no changes are required when
sch-matrix
is re-run.
pcb-matrix
Usage
pcb-matrix_0 <configuration filename>
Description
The
pcb-matrix script creates a new layout by coping each
Element,
Polygon,
Via and
Line from an input file to an output file multiple
times. Each layout, from the input file, is positioned as defined by
the parameters in the configuration file. For each
Element the reference designator is updated to maintain
unique reference designators in the output file.
In a PCB file there is a variety of data prior to the start of the
layout ({\em e.g.} user interface settings, character symbols) . It
does not seem desirable to replicate all of that data. Rather than try
to guess where the layout starts the
pcb-matrix program requires a
marker line in the input file to indicate the start of the layout.
The marker line is a line containing only the string
#####__PCB__##### which is a legal PCB comment line. This marker
line has to be reinserted each time you save the PCB layout.
The start of the layout seems to reside after all of the symbol
declarations and before the vias.
pcb-matrix will copy
all of the lines prior to the marker to the output file
verbatim. After the marker line is read the remaining lines will be
output
r x
c times in a matrix (where
r is the number of rows and
c is the number
of columns specified in the configuration file).
Adding Circuitry to the Output PCB Layout
Usually additionaly circuitry will need to be added to the output
PCB layout to complet a design. However, everytime
pcb-matrix is run
the output layout is overwritten.
If you embed the output layout in your design using the
load layout data to paste-buffer
command then you can reload it if changes need to be made. Since the
output layout is self-contained only the peripheral connections will
need to updated. To reload an output layout into your design:
- Delete the peripheral connections that connect the output layout to your design.
- Delete the output layout.
- Use
load layout data to paste-buffer to add the output layout
- Add the peripheral connections.
Creating Configuration Files
The configuration file format is the same for
sch-matrix
and
pcb-matrix. Each file can contain comments, empty
lines and lines that set parameters. Comments start with a
# and proceed to the end of the current line. Comments
and empty lines are ignored by the parser. The lines that set
parameters are in the format:
name | parameter value
where parameter name is one of the names listed in parameter table.
| Name
| Type
| Description
|
x0 | Integer | the x coordinate (in mils) of the starting position in the output file
|
y0 | Integer | the y coordinate (in mils) of the starting position in the output file
|
xoffset | Integer | the center-to-center column spacing (in mils)
|
yoffset | Integer | the center-to-center row spacing (in mils)
|
last_col | Ordinal | the ordinal of the last column (column ordinals start at 0)
|
last_row | Ordinal | the ordinal of the last row (row ordinals start at 0)
|
input_filename | String | the name of the file containing the structure that will be replicated
|
output_filename | String | the name of the file that contains the replicated stuctures
|
Example
Electronic Load
|
| Figure 1 - Load Cell Schematic
|
Occasionally a circuit design consists of a group of elements, a cell,
that needs to be replicated multiple times. One example is an
electronic load. An electronic load is a circuit that sinks current
and is an essential instrument in power supply test.
Typically an electronic load consists of multiple load-cell circuits
in parallel. Creating a load using multiple cells increases the total
current sinking capability of the load. A schematic of a simplified
load-cell circuit is shown in Figure 1. The circuit consists of
an op-amp, an N-channel MOSFET and current sensing resistor.
Load Schematic
When creating the load-cell schematic the nets that are to have
cell-to-cell connections need to have sufficient length so that they
overlap after replication. The ground net and the net from the drain
of Q1 are long enough so that an
xoffset value of 3200 in
the configuration will overlap the nets in the output file.
Prior to running
sch-matrix all of the reference
designators need to be assigned.
sch-matrix will uniquely
number all of the components in the output file based upon the
assigned values in the input file.
The configuration file for
sch-matrix is shown
here.
xoffset defines the cell
spacing for columns and
yoffset defines the cell spacing
for rows. The
lastcol and
lastrow values
define a 1x4 matrix.
The output schematic shown in Figure 2 is the result of running
sch-matrix using the
schematic
configuration file. Notice that the horizontal nets have been
connected and the reference designators of the copied cells have been
uniquely assigned.
|
| Figure 2 - Load Schematic
|
Load PCB
|
| Figure 1 - Load Cell PCB
|
After creating the schematic for the load-cell run
gsch2pcb and
create a layout for a single load-cell. An example load-cell layout is
shown in Figure 3.
In the load-cell layout the two high current traces are running
parallel on the component side of the board along the top of the cell.
The op-amp power and positive-input traces are running parallel on the
solder side of the board at the bottom of the cell. All of the
parallel traces are ≈950 mils long. Setting an
xoffset of 900mils will create an overlap between the
cells in the output file.
Running
pcb-matrix with the PCB
configuration file produces the layout in
Figure 4.
|
| Figure 4 - Load PCB
|
Schematic Configuration File
# x0 the x coordinate of the starting position in the output file
# y0 the y coordinate of the starting position in the output file
# xoffset the column spacing
# yoffset the row spacing
# last_col the ordinal of the last column (column ordinals start at 0)
# last_row the ordinal of the last row (row ordinals start at 0)
# input_filename the name of the file containing the schematic
# that will be replicated
# output_filename the name of the file that contains the schematic matrix
x0 | 500 #%\label{lst:cfg-sch x0}%
y0 | 100 #%\label{lst:cfg-sch y0}%
xoffset | 3200 #%\label{lst:cfg-sch xoffset}%
yoffset | 0 #%\label{lst:cfg-sch yoffset}%
last_col | 3 #%\label{lst:cfg-sch lastcol}%
last_row | 0 #%\label{lst:cfg-sch lastrow}%
input_filename | load-cell.sch #%\label{lst:cfg-sch infile}%
output_filename | load.sch #%\label{lst:cfg-sch outfile}%
PCB Configuration File
# x0 the x coordinate of the starting position in the output file
# y0 the y coordinate of the starting position in the output file
# xoffset the column spacing
# yoffset the row spacing
# last_col the ordinal of the last column (column ordinals start at 0)
# last_row the ordinal of the last row (row ordinals start at 0)
# input_filename the name of the file containing the PCB layout
# that will be replicated
# output_filename the name of the file that contains the PCB matrix
x0 | 500
y0 | 100
xoffset | 900
yoffset | 0
last_col | 3
last_row | 0
input_filename | load-cell.pcb
output_filename | load.pcb
