Backannotation is the process of updating schematics to reflect changes made in the layout. This process is used, for example, when the reference designators have been renumbered on the layout, when pins have been swapped (e.g., on an AND gate), or slots have been swapped (e.g., on a multi-gate package). This section describes how to backannotate changes in a PADS PowerPCB layout to a Lepton schematic. The PADS PowerPCB tool supports three types of schematic backannotation:
Currently only reference designator changes are automatically
processed by the PADS to lepton-schematic
backannotation tool. The slot
and pin swapping changes are provided in a report which the schematic
designer must use to manually correct the schematic.
This procedure assumes you have a board layout open in PADS. For the purposes of illustration, assume your schematic is split into two pages in the files pg1.sch and pg2.sch.
lepton-netlist -g pads -o mynet.asc pg1.sch pg2.sch
This will create the netlist file mynet.asc.
original design to compare | mynet.asc |
new design with changes | use current PCB design |
√ | generate differences report |
√ | generate eco file |
comparison options | |
√ | compare only ECO registered parts |
attribute comparison level | |
√ | ignore all attributes |
Click the ‘OK’ button to create the ECO file.
pads_backannotate file.eco pg1.sch pg2.sch | tee backanno.log
where file.eco is the name of the ECO file created previously and pg1.sch and pg2.sch are all of your schematic pages. This will apply the reference designator change portion of the ECO file and also generate a list of pin and slot swapping which must be performed by hand. The file backanno.log will contain a log of the session that can be refered to when performing the pin and slot swapping.