Bug #3269

osmo-e1-xcvr has magnetics not placed the right way

Added by tnt 6 days ago. Updated 3 days ago.

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It seems the footprint for the T1094NL transformer in the library is wrong.

The pads in the schematics are correct but their position on the footprint is wrong. P$16 is where P$1 should be, P$15 is where P$2 should be and so on and so forth.
Also pads have the default P$nn which is probably a clue as to what happened :p

The result is that there is no orientation of the transformer that will give the right result because one side is 1:1 and the other is 1:2.

Currently for the RX path, this has no effect. Primary and secondary are swapped but it's a 1:1 turn ratio.
For TX however, the '2' turn ratio should be on the line side and instead it's on the LIU side, so the pulses will end up being 1/4 amplitude of what they should be.


Bug #3270: Fix T1094NL symbolResolvedmschramm

Bug #3271: Fix T1094NL footprint in libraryResolvedmschramm


#1 Updated by laforge 6 days ago

  • Assignee set to laforge

I'm sorry for the fuckup :( I guess we could do some new boards and re-cycle the magnetics and LIU, as those are the expensive parts.

#2 Updated by tnt 6 days ago

I don't think that's necessary.

(1) it might just work since the pulse are just attenuated by 1/4 and for short distance it's fine
(2) You can rework to connect one of the pin on the LIU side to the center tap instead, this would bring in a 1:1 ratio. Not the expected 1:2 but it means the pulses are only 1/2 instead of 1/4 which is already much better.

Since the board is only for experimentation I think the existing one will be good enough for that purpose. Of course still worth fixing the footprint for future use :p

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