EEC 116 - The Magic and IRSIM CAD Tools

Are things not working? Try these first

1. Check circuit
1. Check transistor-level schematic (if you don't have one, draw one now).
2. Check stick diagram, make sure the circuit matches the schematic (if you don't have one, draw one now).
3. Check that magic layout matches stick diagram.
4. Verify magic connections and node names.
• Select all important nodes one at a time, by pressing s two or three times in magic. Check power and ground nodes also. Verify that all connections are as you expect and that there are no shorts or opens.
• Type 'getnode' to get the "real" node name. This is the name that IRSIM will know about.
5. Fix any DRC errors in the circuit. You can find the cause of an error by placing the box around the white dotted paint and using 'drc why' or ?.
2. Check extraction
1. If magic gives warnings when you extract your layout,
1. Put a box around white warning paint and type 'feedback why'.
2. Fix cause of warning(s).
3. Type 'feedback clear' to clear warnings.
4. Re-extract
3. Debug circuit
1. Select important nodes (including inputs and outputs of gates connected to cell inputs and outputs) one at a time, using s in magic. Check power and ground nodes also.
2. Type 'getnode' to get the "real" node name.
3. Type 'analyzer nodename' in IRSIM to see the signal inside your simulation.
4. Debugging rule: start at inputs, move a node at a time toward the outputs.
   1. Check block inputs are correct
   2. Check outputs of gates which have block inputs as the gates' inputs
   3. [repeat.] You will find the bug(s).
4. If nothing is working right
Copy your top-level .mag file to temp.mag and remove layout from temp.mag until it works.

Using IRSIM to find slow circuit paths

• To speed up a circuit, use a small step size to determine the slowest path in a simulation. Then type 'path nodename' to see the transitions in that node all the way back to the input. The slow nodes in that path are the ones to speed up!

IRSIM freezing

• If the IRSIM analyzer window freezes, doesn't redraw, and doesn't allow you to change anything, type s until it unfreezes. You normally shouldn't have to type more than 2 or 3 s characters.

Links

• The "Official" Magic 7.2-7.5 Site
• The "Official" Magic 7.0/7.1 Site
• The "Official" Magic 6.5.1 Site

2004/04/08  Written
2004/05/20  Added more magic tips and irsim section
2004/05/24  Schematic tips
2004/05/27  Irsim path command
2005/05/23  Updated for spring 05
2005/05/31  Added area calculation thanks to Jeremy Webb
2006/04/11  Updated for Spring 2006
2006/06/05  Added top-level power node hint
2008/04/30  Touched up magic error messages
2009/06/01  Touched up debugging notes
2010/10/19  Touched up and moved portions to magic.tips.html
2012/12/09  Added suggestion to copy cell and remove layout