OpenIMU330BI - Decoupling Needed? Eval board doc...

Adam Jackson

Hi There,

Probably a non issue, but...

I'm about to turn a board that is based on the OpenIMU330BI, usually, I look at the eval board and mimic that, but the doc below lists the DMU380 as the eval, just like the OpenIMU300.

https://buildmedia.readthedocs.org/media/pdf/openimu/latest/openimu.pdf

I just got my OpenIMU380 eval board in, and indeed, it looks just like the OpenIMU300 board.

The OpenIMU330 is pin / form factor adapted to be in OpenIMU300 form factor. The OpenIMU330 appears to be purely passively pin adapted by a small PCB. I dont see any capacitors.

Main question(s):

Is it possible to get a copy of the OpenIMU330 to OpenIMU300 pin adapter PCB schematics?
Also, are any local decoupling capacitors needed, or are the OpenIMU330's decoupling needs fully accounted for under the lid?

Li YiFan

@Adam-Jackson Hi Adam jackson,

For the OpenIMU330BI BGA package unit, the recommendation peripheral sch interface：

The voltage range of the unit VIN if from 2.95V to. 5.5V.

2.For the OpenIMU330BI EVB board, pin to pin with OpenIMU300ZI unit.

Jack Morrison

Is there an internal pulldown on BOOT0, or should that be added on the board if not using that pin?

Li YiFan

@Jack-Morrison Yes, there is 10K pulldown internal connected with boot0/PH3.

Jack Morrison

The drawing above shows the bottom view of the BGA package with A1 at lower right, which fits with the top view's dot on lower left. Can I suggest that the drawing at https://openimu.readthedocs.io/en/latest/330BI/mechanical.html also label the pin view as bottom view (so a mirror image of the PCB footprint)? More importantly, the pin view in the spreadsheet at https://openimu.readthedocs.io/en/latest/330BI/pinout.html is labeled "top view" when in fact it's the bottom view (rotated but not mirrored).

Li YiFan

@Jack-Morrison Hi Jack, thanks for your advise, we will update the document shortly.

Adam Jackson

https://forum.aceinna.com/topic/118/openimu330bi-error-in-openimu330bi_pin_definition-xlsx

Now I've got to spin 5x boards!

Also be aware that the Mouser parts library made the same error, then fixed it (after I used it), while also updating their terms and conditions.

I'm hoping maybe someone at Aceinna might do the right thing and send me 5x new IMU330's

Jack Morrison

Could you also please show the axis orientation on the mechanical drawing?

Li YiFan

@Jack-Morrison Hi Jack, please check the axis orientation

Jack Morrison

Thank you. (Puzzling that the data interface selection would matter)