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I have a heating controller hidden in a cupboard which is itself hidden at the back of a cupboard filled with file boxes... it is a pain to remove dozens of file boxes and a couple of shelves just to be able to see the controller LEDs.

Maybe a webcam is a solution, but there are some constraints:

  1. I have only 12 cm between the inside surface of inner cupboard door and the front of the control panel. Somehow the camera thickness lens-to-back plus its minimum (almost) focussed distance has to fit in 12 cm.

  2. The inner cupboard is in total darkness apart from the LEDs I'm trying to monitor.

NEEDS:

Mac compatible

90° viewing angle (could survive with around 70° but this omits the non-critical "pump on" LED.

NICE TO HAVE:

So cool if the cam could connect to my WiFi, but USB power & data will do.

DON'T CARES:

Blurred image due to imperfect close-focus: I only need to differentiate between On / Off / 2Hz flashing LED and between Red or Yellow on each of the six critical LEDs

Hi-Res: I only need enough definition to determine which LEDs are doing what.

Frame rate: I only need to see the 2 Hz flash -- 4 fps should do that.

OPTIONS:

I have no issue to drill through the 1.3cm inner door if there is some alternative device (a video door peep-hole for example). I have any amount of space OUTSIDE the inner-cupboard door.

So there you have it: thin webcam with close focus ability on high-contrast scene (bright LED in total darkness).

Suggestions?? Thanks Chris

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  • As cool as the webcam solution is, it seems like it'd be a lot more elegant just to wire the LEDs to come through the cabinet. Is there something impeding that? Alternatively, what about installing optics and mounting the camera outside?
    – JMY1000
    Jan 7, 2018 at 21:36
  • @JMY1000, This is a closed-box Honeywell underfloor heating controller -- me rewiring the LEDs is, at least, hugely invasive and has possibly expensive consequences (thermal & financial) if my intervention goes banana shaped. I understand your elegance-think (I already tried light pipes), but I prefer to see the beast "as is" on camera.
    – Chris-guest
    Jan 7, 2018 at 21:52
  • I see. Yeah, besides that, the only thing I can think of is fibre optics, but a camera seems to be a reasonable solution. That or individual light sensors taped down to the controller.
    – JMY1000
    Jan 7, 2018 at 22:03
  • Light pipes are a cool idea, too bad it doesn't work for you. A light pipe can be as simple as an acrylic rod with good optical contact on the source and a polished end at the destination, or even a frosted one.
    – fred_dot_u
    Jan 7, 2018 at 22:16

2 Answers 2

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If you haven't rejected the option of using a Raspberry Pi with pi-cam as a system, you'd be getting all of your required features, plus remote access, as the pi could be configured to display the images when polled by a web browser. I'm using Octoprint on my 3D printer, but use an ordinary web cam attached to the Pi. I am able to view images via web browser from the web cam, and I know that a pi-cam would provide the same capability.

A quick check on the pi-cam shows that good focus has been accomplished as low as 30 mm with the V2 NoIR camera module. There are many specifications for both versions of cameras here: Raspberry Pi Camera Specifications

There are tons of resources (kilograms?) for configuring a Pi with an operating system of choice, and almost as many for configuring the camera and accessory software. It's clearly not possible to list them all buy I've picked a couple in the links to show some appropriate representative resources.

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  • Whoooo - investigating tomorrow (23:07 here and perhaps a glass of wine or two has passed my lips -- doesn't aid smart thinking). 30mm focus sounds magical, view angle I will discover tomorrow. Many thanks fred.u
    – Chris-guest
    Jan 7, 2018 at 22:10
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The simple solution was to go out and buy a cheap webcam (cheaper than PiCam without the Pi): the image is severely unfocussed but perfectly good enough to know the status of each LED (but not wide-angle enough to capture the non-critical "pump on" LED). The image is also mirror-image (took me a while to work out why), but I guess that will sort itself out if I video-chat to my mac from another machine.

As a newbie to Pi there is no way I could implement PiCam within the time my wife will accept all the file boxes strewn around the place, but it is a fascinating project that I will pursue. I've known about Pi since its early days but never bumbled into a use for it until now. Thanks fred_dot_u for the suggestion.

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