gEDA-user: Specification of Rotations for Auto Assembly

[Rick Collins <gnuarm.2006@xxxxxxxxx>]

This seems like a pretty sharp group.  One of the problems I 
consistently have is generating an XYRS file for auto assembly of my 
boards.  The X and Y require a specified origin and orientation of 
the board, which is done in the fab drawing.  The side is pretty 
clear as well.  But I always have trouble with the rotations.  There 
are two sides and even if you pick a convention for the angle of 
origin and the direction of rotation, you still have to decide if the 
bottom side is viewed from the top or the bottom.

When I have asked assembly houses about what they assume as 
convention, I never get an answer.  They just tell me that they need 
the X and Y data along with the side.  They basically figure out or 
at least verify the rotation data for themselves.

Is that what you find?  It just seems very odd that there is no 
accepted and widely used convention for rotations.  I found info from 
IPC that says pin 1 in upper left corner is 0 degrees for ICs.  But 
I've seen nothing that addresses how to spec the bottom side 
components.  A FreePCB companion program. FpcPlace assumes all 
rotations are CCW and viewed from the top.  But the footprint 
generator makes the footprint with pin 1 in the lower left which 
screws everything up, or so the FpcPlace developer says.  It looks to 
me like the FpcPlace program is not correct.

Rick



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