Sega Genesis controller button contact in eagle?

On 3/05/2014 8:50 a.m., David Frost wrote:

I need to make a Sega Genesis controller button contact in eagle. This

looks like a circle with a hole on one side and a smaller circle in the

center. These are the two contacts, so when the button is pressed pin1

in connected to pin 2. I see through-hole and SMD pads in the library

tool, but not sure how to draw these odd shapes to make a custom pad.

Any ideas?

First read HELP> PAD> Arbitrary Pad Shapes

Those are the rules for creating an Arbitrary Pad Shape.

Also, you will likely need to pick up the skills to form arcs using the

WIRE command and the CTL key. Read HELP > WIRE > Drawing Arcs.

Polygons can be time consuming so you have to be smart in the way you work.

You could do it along these lines. Paste into the library editor  the

lines in Upper case that follow so you can see the process.

Open your library and start a new package

Lay down some guides

GRID MM; SET WIRE_BEND 2; CHANGE LAYER 51; WIRE 0 (0 10)(0 -10); WIRE 0

(-10 0)(10 0);

Lay down a guide for the outer annulus

CIRCLE 2 (0 0)(4 0);

Build a stick polygon roughly. We'll make the polygon wire

8mil(0.2032mm) wide

CHANGE WIDTH 0.2032mm;

CHANGE LAYER 1;

POLYGON 0.2032 (-5 .5)(-3 .5)(0 3)(3 0)(0 -3)(-3 -.5)(-5 0)(0 -5)(5 0)(0

5)(-5 .5);

Now use the 'Info' tool and change the 'Curve' of the long sides of the

polygon to match the guiding circle. The outer sides will need to be

made 90 and the inner sides -90 to get the curves bending the correct way.

Next make the grid finest so we can match the rough polygon to the circle

GRID FINEST;

Now, at the orthogonal positions move the polygon to match the circle.

Pay some attention to getting the join on the left looking good but

there is a goal of not having the points overlap more than 49% or the

wire width as the polygon wont like that. At the finest resolution there

is a low change of this happening.

Now you need to place a SMD within the polygon for a track on the board

to connect to.

SMD 1 1 (-4 0);

You need to keep the solder mask off the contact so add a circle on that

layer.

CHANGE LAYER 29; CIRCLE 0 (0 0) (0 5.1);

Look at the 'Information' of the SMD and un-check 'Thermals', 'Cream',

and 'Stop'.

The center contact can be done with a single SMD with 100% rounding or a

polygon surrounding a smaller SMD. I'll leave that to you.

HTH

Warren