topic Re: Meander Length Inconsistency in Fusion Electronics Forum

Meander Length Inconsistency

chuck_toddN7PTC — Tue, 04 Jun 2024 22:11:54 GMT

I am routing a length constrained bus and setting meander to 52 mm.

When I meander the route/trace, the signal in design manager shows me a longer length than what I am asking for. All other nets have met the criteria. See the screenshot.

Thanks.

Re: Meander Length Inconsistency

jorge_garcia — Wed, 05 Jun 2024 16:17:43 GMT

Hi @chuck_toddN7PTC,

I hope this message finds you well. What tolerance have you set for meanders in the DRC? The default tolerance is +/- 10mm. In that case this level of discrepancy would be OK.

Additionally you can get tighter coils by setting Gap Factor to 1. You can find both these settings in the DRC -> Misc Tab

Let me know if you continue to run into problems.

Best Regards,

Re: Meander Length Inconsistency

chuck_toddN7PTC — Wed, 05 Jun 2024 16:24:06 GMT

@jorge_garcia

Here are my settings.

Re: Meander Length Inconsistency

jorge_garcia — Wed, 05 Jun 2024 18:03:33 GMT

Hi @chuck_toddN7PTC,

I hope you're doing well. Let's check something, if you look in the design manager below where you have the screenshot you'll see all the elements that make up that length. Could you take a look at those segments and show me the list?

I'm going to contact one of our devs to take a look at this. I think there is a reason for the discrepancy but I'm not remembering it right now.

Best Regards,

Re: Meander Length Inconsistency

chuck_toddN7PTC — Wed, 05 Jun 2024 19:18:51 GMT

@jorge_garcia

Here is the information you requested.

Re: Meander Length Inconsistency

jorge_garcia — Wed, 05 Jun 2024 20:33:03 GMT

Hi @chuck_toddN7PTC,

I hope you're doing well. This trace has a lot more segments than I thought. Question, does this net go in between multiple components?

For example, Let's say the net goes between 3 components. When you meander a trace only the length between two of them is taken into account, the Design manager will report the full length of the net between all 3 components. Looking at the image it seems that could be happening.

Best Regards,

Re: Meander Length Inconsistency

chuck_toddN7PTC — Wed, 05 Jun 2024 20:58:00 GMT

@jorge_garcia

If what you say is true. The length in the design manager should not be equal to 52mm for any of the traces that are meandered. Since there is additional trace length that is not part of the trace being meandered.

When a signal is highlighted in the Design Manager panel the whole length of the route is highlighted, not just the meandered portion.

Here is the suspect net. The Design Manager panel shows that this net doesn't meet the 52mm meander command request.

This net has a similar topology and shows that it does meet the requirement. Realize there is one less component in this path.

Thanks.

Re: Meander Length Inconsistency

jorge_garcia — Thu, 06 Jun 2024 21:03:50 GMT

Hi @chuck_toddN7PTC,

Looking at the pictures I'm noticing that in the net that is reporting 53.xx mm you have an unrouted airwire. Could you try re-routing that trace completely and then meandering. I wonder if the airwire is messing with the meander reading.

I spoke to the devs that are currently working on meander and a lot of this behavior has been re-implemented so this inconsistency will be resolved shortly. That doesn't help you solve it now but I thought it prudent to let you know.

Best Regards,