Select USB panel-mount pigtail for RasPI - Githubissues

RespiraWorks / Ventilator

Fully-featured ICU ventilator design, optimized for manufacture using commonly available components and free to license. Repository tracks all mechanical, electrical and systems design, software, requirements and regulatory documentation.

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Select USB panel-mount pigtail for RasPI #1280

Closed martukas closed 1 year ago

martukas commented 2 years ago

We need an outside-facing USB port on the enclosure to plug in peripherals to control the RasPI. Primarily this would be for keyboard and mouse to aid in deployment, commissioning, testing and troubleshooting. This is especially useful while in the R&D phase, but may also be needed in the final product for maintenance tasks.

This should be a Type-A USB extender with the female end being panel-mountable somehow. It could be mounted to the acrylic in v0.4, or some aluminium sub-panel, or directly to the enclosure sheet in some later version.

The cable needs to be long enough to run from the RasPI to the back-panel.

martukas commented 2 years ago

We are currently stocked up on 20x of these: https://www.cableleader.com/1ft-usb-2-0-panel-mount-type-a-male-to-type-a-female-cable.html

Some experimentation with the 6mm acrylic has determined that:

hole for USB port should be 7mm x 16mm
holes for mounting screws should be 29mm apart, ~4mm diameter

Possible shortcomings:

Included screws are not long enough for acrylic mounting, so have to source longer replacements
Insert nuts are not metric - M3 seems to fit, but is probably some US size, I do not have a thread gauge here to determine it
1ft cable is long enough to allow port to be mounted on the west side of the back-panel, but not not long enough if we want it on the east side by the power inputs, further from the oxygen inlet. Not necessarily a problem.

martukas commented 2 years ago

The screws appear to be imperial no.4/40 This is unfortunate. Might stay with this for now, but we should look for a different more metric-friendly component in future iterations.

martukas commented 2 years ago

Embedded nuts are blind, so screw length must be upper-bounded.

length of provided screws = 5.96mm
acrylic thickness = 6.35mm

Total is therefore <=12.31mm Converted to imperial this is <=0.4846"

Closest fit is 7/16" (=0.4375mm)

Proposed item: https://www.mcmaster.com/92949A111/

martukas commented 2 years ago

This also requires an elbow, because the male plug would clash with one of the enclosure-mounted cooling fans to the side of the PCB. Possible option: https://www.amazon.com/gp/product/B07S6B5X76

martukas commented 2 years ago

Some USB devices are quite thick and would require too wide a cutout in the acrylic. Therefore, we are doing another sub-panel of thinner (1/8") acrylic. This means that screw should be shorter.

It appears that the included screws are long enough, so may not need an additional part here, but just to have something sensible in CAD and BOM, let's do the same calculation as above: 5.96mm+3.175mm = 9.135mm -> 0.36" Closest fractional candidate upper bounded by this is 5/16" which is = 0.3125mm

Candidate part: https://www.mcmaster.com/97763A302/