There is a jumper SJ2 on the schematics of Arduino Nano RP2040 Connect. I have two questions. Why is the jumper drawn unusually (closed with hug) on the schematics? Why the 0 ohm resistor into the jumper SJ2 is missing (his number is missing) from the BOM (Bill of material)?
Not sure what a "hug" means. The schematics should be drawn with the default position.
You mean missing from the diagram like you show? If so that is why it is not on the BOM.
I think this sort of optional link is normally closed by a solder blob.
No, this is not a drop of solder. This is a 0603 resistor labeled “Solder Jumper 0201 CLOSED with HUG”
The picture of the board seems to have that same physical layout for the traces as is pictured in the schematic, and I'm not sure whether the jumper is a 0 ohm resistor or the 330 ohm shown on the schematic. Might be to ensure a smaller solder blob if someone wanted to remove the 0 ohm resistor and then later reconnect it using a solder blob.
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I see you posted a picture of the board layout while I was typing.
In the
BOM = SJ2 = Part Number CRCW02010000Z0ED. This is 0 Ohm SMD-0603 resistor
I think it's safe to assume that "SJ" is short for "Solder Jumper". Solder blobs can not be reliably machine placed on a production line, that is why a 0 ohm resistor might be used. But leaving blob compatible traces allow it to be done manually, later.
The symbol may be ad-hoc, or just from the imagination of someone that made the footprint library.
Where does it say this?
Maybe a Holiday Hug?
I know in PCB design “hug” means to route as close as possible to obstacles but I don’t quite see the connection here. No pun intended.
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