mirror of
git://projects.qi-hardware.com/fped.git
synced 2024-11-22 08:38:26 +02:00
5d7ab083a3
- README: added that loops can also execute zero times - accept labels only at the beginning of a line - rectangles and lines no longer use the bounding box for drawing (caused offset problems since we now correct for the line width) - dist_rect and inside_rect no longer require their input pre-sorted - pad instances now have their own structure and no longer abuse the bounding box to know the pad coordinates - Makefile: use $(GEN) for fig2dev, to reduce chattiness - when dragging a point, the symbol is now adjusted accordingly - added moving of rects, pads, circles, and arcs - added creation of pads - moved rotate_r from gui_inst.c to coord.c - new function "theta" that combines most of the angle calculations - save_pix_buf: y < 0 clipping changed width, not height git-svn-id: http://svn.openmoko.org/trunk/eda/fped@5386 99fdad57-331a-0410-800a-d7fa5415bdb3
357 lines
9.1 KiB
Plaintext
357 lines
9.1 KiB
Plaintext
fped - Footprint editor
|
|
=======================
|
|
|
|
fped is an editor that allows the interactive creation of footprints of
|
|
electronic components. Footprint definitions are stored in a text format
|
|
that resembles a programming language.
|
|
|
|
The language is constrained such that anything that can be expressed in
|
|
the textual definition also has a straightforward equivalent operation
|
|
that can be performed through the GUI.
|
|
|
|
|
|
Motivation
|
|
----------
|
|
|
|
KiCad already includes a footprint ("module") editor, so why do we need
|
|
a new one ? The issue with footprint generation for KiCad is that the
|
|
built-in module editor is basically a drawing program that only captures
|
|
the result of the module author's interpretation of a footprint drawing,
|
|
but does not include the steps that led to this construction.
|
|
|
|
Furthermore, accurate measuring of dimensions in the drawing can only be
|
|
done manually in the module editor, which makes review difficult and
|
|
time-consuming.
|
|
|
|
In fped, the construction process is made explicit and each step can be
|
|
expressed in terms of the parameters that appear in the vendor's
|
|
drawing. Dimensions can be explicitly measured and the results can be
|
|
included in the graphical output generated by fped.
|
|
|
|
Directly using parameters and construction steps from the reference
|
|
drawing reduces the risk of mistakes. Visualizing the construction
|
|
process and verificative measurements helps efficient and accurate
|
|
review.
|
|
|
|
|
|
Footprint definition file format
|
|
--------------------------------
|
|
|
|
Footprint definitions are stored in text files. The program "fped" reads
|
|
and (soon) writes such files, visualizes their content, and provides a
|
|
graphical editor for them.
|
|
|
|
The syntax is unique and draws from elements of a variety of languages
|
|
commonly found on unix systems. One specialty is that there are no
|
|
reserved words - the language keywords appear only at the beginning of
|
|
a line and can thus be recognized as such without restricting their use
|
|
for identifiers. This reduces the risk of creating incompatibilities
|
|
with existing designs when introduction future language features.
|
|
|
|
fped uses the C preprocessor for comments, conditional compilation,
|
|
and - to a limited extent - also macros. Long lines can be split by
|
|
ending them with a backslash. If multiple items need to be placed in a
|
|
single line, e.g., in a macro, they can be separated with semicolons.
|
|
|
|
|
|
Geometry model
|
|
--------------
|
|
|
|
The geometry model consists of frames, vectors, and objects. The shape of
|
|
objects is defined by a number of points. These points are produced by
|
|
concatenating vectors.
|
|
|
|
E.g., to draw a line from (1mm, 1mm) to (2mm, 2mm), one would make a
|
|
vector from the origin to (1mm, 1mm) and one either from the origin or
|
|
from the previous vector to (2mm, 2mm), and then make a line connecting
|
|
the two points.
|
|
|
|
|
|
Units
|
|
- - -
|
|
|
|
fped can calculate in mm and mil. Units are specified by following a
|
|
number with "mm" or "mil", separated by zero or more spaces or tabs.
|
|
|
|
Examples:
|
|
|
|
1mm
|
|
2 mil
|
|
|
|
Units can be mixed in calculations, e.g.,
|
|
|
|
set a = 1mm+20mil
|
|
set b = 10*1mm
|
|
|
|
All values used as dimensions must be either mm or mil.
|
|
|
|
|
|
Vectors
|
|
- - - -
|
|
|
|
Vectors can be anonymous or they can be named for future reference:
|
|
|
|
vec <base> ( <x-expr>, <y-expr> )
|
|
<identifier>: vec <base> ( <x-expr>, <y-expr> )
|
|
|
|
The base can be one of the following items:
|
|
|
|
- @ is the origin of the frame containing the vector
|
|
- . is the end of the previous vector in this frame
|
|
- <identifier> is the name of a previous vector in the same frame
|
|
|
|
The following example would draw the line described in the previous
|
|
section:
|
|
|
|
a: vec @(1mm, 1mm)
|
|
b: vec .(1mm, 1mm)
|
|
line a b
|
|
|
|
|
|
Silk screen objects
|
|
- - - - - - - - - -
|
|
|
|
The output of fped is a footprint definition that contains pads and silk
|
|
screen drawings (we may add more layers in the future). These items are
|
|
called "objects". Their geometry is defined through points obtained with
|
|
vectors.
|
|
|
|
A line connects two points:
|
|
|
|
line <point-a> <point-b> [<width>]
|
|
|
|
The points can be specified with @, ., and an identifier, just like
|
|
a vector base. The option width specifies the thickness of the silk
|
|
screen line. If omitted, a hard-coded default of 15 mil is used.
|
|
|
|
A rectangle has sides parallel to the x and y axis and is defined
|
|
by two diagonally opposite corners:
|
|
|
|
rect <point-a> <point-b> [<width>]
|
|
|
|
A circle is defined by its center and a point on the circle:
|
|
|
|
circ <center> <point> [<width>]
|
|
|
|
This example draws a unit circle:
|
|
|
|
vec @(1mm, 0mm)
|
|
circ @ .
|
|
|
|
An arc is like a circle, but the part of the circle drawn is determined
|
|
by two points. The first point determines the radius and the starting
|
|
angle. The second point only determines the end angle but its distance
|
|
from the center is ignored.
|
|
|
|
arc <center> <radius> <end> [<width>]
|
|
|
|
The arc is drawn in a counter-clockwise direction. The following example
|
|
draws an arc of the unit circle in the x > 0, y > 0 quadrant:
|
|
|
|
from: vec @(1mm, 0mm)
|
|
to: vec @(0mm, 1mm)
|
|
arc @ from to
|
|
|
|
|
|
Pads
|
|
- -
|
|
|
|
Pads are similar to rectangles, but they also have a name.
|
|
|
|
pad "<name>" <point-a> <point-b>
|
|
|
|
Variables can be expanded in a pad's name by prefixing their name with
|
|
a dollar sign. The ${name} syntax is also available.
|
|
|
|
Example:
|
|
|
|
vec @(1mm, 1mm)
|
|
pad "1" @ .
|
|
|
|
|
|
Measurements
|
|
- - - - - -
|
|
|
|
Measurements show the distance between two points:
|
|
|
|
meas <point-a> <point-b> <offset>
|
|
|
|
The offset is the distance from the imaginary line connecting points A
|
|
and B the measurement line is draw:
|
|
|
|
- if the offset is 0mm, the line will connect A and B
|
|
- if the offset is positive, the line would be on the left-hand side when
|
|
traveling from A to B
|
|
- if the offset is negative , the line would be on the right-hand side when
|
|
traveling from A to B
|
|
|
|
Example:
|
|
|
|
a: vec @(-1mm, 1mm)
|
|
b: vec @(1mm, 1mm)
|
|
meas a b 0.2 mm
|
|
|
|
|
|
Frames
|
|
- - -
|
|
|
|
Frames are used to group things and to reuse them multiple times. Frames
|
|
must be defined before they can be used:
|
|
|
|
frame <name> {
|
|
... items ...
|
|
}
|
|
|
|
Once defined, a frame is placed at a given location with
|
|
|
|
frame <name> <point>
|
|
|
|
The frame definitions must precede all other items in a footprint
|
|
description. Frames cannot be defined inside other frames, but frames
|
|
can invoke each other recursively.
|
|
|
|
For example, this puts two unity squares, one centered at (0 mm, 0 mm),
|
|
the other at (2 mm, 0 mm):
|
|
|
|
frame unit_square {
|
|
a: vec @(-0.5mm, -0.5mm)
|
|
b: vec .(1mm, 1mm)
|
|
rect a b
|
|
}
|
|
|
|
frame unit_square @
|
|
vec @(2mm, 0mm)
|
|
frame unit_square .
|
|
|
|
|
|
Names and variables
|
|
-------------------
|
|
|
|
fped uses several name spaces:
|
|
|
|
- frame names occupy one global name space
|
|
|
|
- vector names occupy name spaces delimited by the frame they're
|
|
contained in. A vector name is only visible inside the frame in which
|
|
it is defined.
|
|
|
|
- variable names occupy name spaces delimited by the frame they're
|
|
contained in. A variable lookup starts in the frame in which the
|
|
corresponding expression appears and propagates to outer frames
|
|
until the variable is found.
|
|
|
|
- pads occupy one global name space (this is currently not enforced)
|
|
|
|
Note that names cannot be redefined. E.g., this does not work:
|
|
|
|
set a = 1
|
|
set a = a+1
|
|
|
|
The names spaces of frames, vectors, variables, and pads are separate
|
|
from each other.
|
|
|
|
|
|
Simple variables
|
|
- - - - - - - -
|
|
|
|
A variable with a single value is defined with the following
|
|
assignment syntax:
|
|
|
|
set <identifier> = <expression>
|
|
|
|
Example:
|
|
|
|
set a = b+2
|
|
|
|
|
|
Loops
|
|
- - -
|
|
|
|
A loop is a variable with a range of values:
|
|
|
|
loop <identifier> = <from>, <to>
|
|
|
|
The variable assumes all the values i for <from> <= i <= <to>, in
|
|
increments of one. E.g.,
|
|
|
|
loop n = 1, 3
|
|
|
|
and
|
|
|
|
loop n = 1, 3.5
|
|
|
|
both assign the values 1, 2, and 3 to the variable "n". The
|
|
following loop would not execute at all:
|
|
|
|
loop n = 1, 0
|
|
|
|
When a loop is executed, the objects contained in the body of the
|
|
enclosing frame are generated for each value of the variable. If
|
|
a frame contains multiple loops, all possible combinations of the
|
|
values are generated.
|
|
|
|
The following example draws three concentric circles around the
|
|
origin, with radii 1, 2, and 3:
|
|
|
|
loop x = 1, 3
|
|
vec @(x*1mm, 0mm)
|
|
circ @ .
|
|
|
|
|
|
Tables
|
|
- - -
|
|
|
|
Tables combine values for multiple variables. Like loops, they are
|
|
used to iteratively generate objects. A table begins with a row of
|
|
variable names, followed by one or more rows with values. Rows are
|
|
enclosed in curly braces and their elements are separated by commas.
|
|
|
|
table
|
|
{ <identifier>, ... }
|
|
{ <expression>, ... }
|
|
...
|
|
|
|
Like loops, tables are iterated to generate objects. The following
|
|
example is equivalent to the one in the previous section:
|
|
|
|
table
|
|
{ x }
|
|
{ 1mm }
|
|
{ 2mm }
|
|
{ 3mm }
|
|
vec @(x, 0mm)
|
|
circ @ .
|
|
|
|
Note that we can set the unit of the values directly in this case.
|
|
|
|
Iteration is performed over rows. All variables of the table are set
|
|
to the value in the respective row at the same time. For example, in
|
|
|
|
table
|
|
{ x, y }
|
|
{ 1, 2 }
|
|
{ 3, 4 }
|
|
|
|
(x, y) assume the values (1, 2) and (3, 4).
|
|
|
|
|
|
Expressions
|
|
-----------
|
|
|
|
Expressions can contain numeric constants (in non-exponential notation),
|
|
variable names, the arithmetic operations +, -, *, /, and unary -.
|
|
Parentheses can be used to change precedence.
|
|
|
|
|
|
GUI
|
|
---
|
|
|
|
Keys:
|
|
|
|
space reset user coordinates
|
|
+, = zoom in (like mouse wheel forward)
|
|
- zoom out (like mouse wheel backward)
|
|
. cursor position to screen center (like middle click)
|
|
* zoom and center to extents
|
|
# zoom and center to currently active frame instance
|