Specctr@ strange behaviour

Dear all,

i am using Specctr@ 10.2 with Acc3l 15.

When aplying rules to the autorouter, i have a behaviour that is not stated on the commands syntax databook.

I am doing a "FANOUT (direction out)" to keep all the vias out of the components boundaries.
But when i SMART_ROUTE, or ROUTE, CLEAN, FILTER... anything... it removes the via positioning that FANOUT did, and puts vias under the components...

Is there a way to change this behaviour ? am i doing anything wrong ?

Thanks in advance, regards.

asena

hi
you have to protect your vias after fanout use this commands

#********** FANOUT CYCLE **********
fanout 5(pintype all)(direction out)(share_len 25)(pin_share off) (smd_share off )(via_share on (maximum_connections 2))(max_len 150)

#********** PROTECT FANOUTS **********
protect all wires ( attr fanout )

hope this is helpful to u

u r welcome to ask further clarification
regards
[/quote]

re:re: Specctr@ strange behaviour

This is exactly what i wanted! works perfect.

It gives me an error of the UNUSED_PINS net not defined... and when i define in the schematic the UNUSED_PINS, it routes all the unused pins to vias, and does not obbey to the FANOUT...

I am getting frustated here... im going nowhere with the Specctr tutorials... and the Autorouting Commands doesnt help, because you never know the results....
And to try all the commands takes agesss....
And the trick is the combination of them.


Do you know of o method...tutorials...book... from where i can learn??
Or do i have to try them all ?


thanks a lot
kind regards


asena 8)

Re: re:re: Specctr@ strange behaviour

Hi asena

Specctra is truly a powerful autorouter, the trick is to know how to drive it properly.

I understand ur frustuation.

there are several places in the internet like this as well as an official forum at www.specctraquest.com where you can sign up for a newsletter, you will receive questions and answers in archived format for similar sitautions.

I am attaching a zip file which has example do files and a document which is kind a of tutorial and it has undocumented commands you can use.

regarding ur situation on single nets
fanout 1 (direction in_out) (location anywhere) (max_len -1) (pin_type signal) (pin_type single)

you can control that by changint the argunebt to the pin_type field.

"single" is for unused pins
"signal" for signal pins
"power" for power signals

or another trick is select all the signals you want to fanout and assign them to a class "Temp"
then

select class temp
fanout 5(pintype active) **** and all the argument you can add

another trick is

select a region and play with it for a while. don't try to auto-route the entire board at the same time, it will never work.

route in an objective fashion, like

1. clock and power
2. critical
3. buses.
4. less critical

etc..

the fence command is very useful to contain the routing within a pre-defined area and it won't allow the routes to stray all over the board

hope this helps you

regards

How to use the command "bundle" to route a group of bus, sometimes it can't autoroute unless you drag them out to make a man-made bus, my questions is "How can I let them be autorouted without my pre-routed?" such as a bundle from BGA.

go around the command

select the desired buses and then create a bundle with the selected

ex

select class add*
; use wild card to select multiple objects P0_addXX and P1_addXX can be selected by using p?_add*

define (bundle bundle1 (nets (selected)) (gap 15 (layer INT1_LAYER4 INT2_LAYER5 INT3_LAYER8 )))

but a word of advice, this won't give you a desired result, because you over strain the auto-router.

an achievable approach will be like this

1. determine the critical buses and decide their flow ex. a pci bus may go from u1 on top right to u30 on bottom right
2. with a help of excel sheet, allocate routing layers in alternate fashion for different buses. make sure that you don't cross the path
ex for a 16 layer brd with 6 internal layers
Bus layers direction
pci int1, int6 H,V
add int2, int5 V,H

3. now take one bus at a time, define a fence such that the desired bus dont stray all over the board

4. make sure that you limit vias and have a via free zone where you expect criss-cross (define the via grid to 25-50mils)

5. route, mitter, and protect the routes after you get the desired result.

this way you save a lot of time and the routing will be more manual like, in the sense, you will spend less time in correcting DRC's after auto-route.

for a start take a test board and practice auto-routing. once you get the hang of it, you will become an expert

best of luck
regards

It's a good idea to define a fence. Sometimes You must be familiar with the chips with tens of connections before you set the rules which will take much time comparing to routing manually. So I prefer to route with "push and drag" when the connection is not very obviously, but I don't want to give up autorouting . How contradictive it is wether to autoroute or not . It's funny.

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Sukohi_Berkut, thanks for your hints on specctra.
Lets talk about fanout, I need to add more stub and via for big smd pads like bulk caps. is any automatic way or I have to do that manully?
Again about fanout: for double sided same component PCBs, you may need to fanout and put via outside the pad stack ring and in-line! how to do that automatic?