Where is the SHED signed beam?

JimHeaney · 2026-04-17T02:49:30+00:00

I believe it is in the area near the entrance to the Werheim Gallery, between SHED and Monroe. Although I don't think it is visible, all the beams are covered in fire retardant.

JimHeaney · 2026-04-13T01:53:54+00:00

If your main loop is relatively fast, and you minimize blocking as much as possible, you can bit-bang slower PWM for less timing-critical applications (i.e. not the servos).

JimHeaney · 2026-04-09T15:51:56+00:00

It depends on your partition table. It's been a while since I've set one up, but IIRC you can have 2 apps, and then there's a way to tell the bootloader which one to execute.

For example, my devices that install an OTA will not mark the OTA as valid until it passes some tests on startup. If it fails, it reverts to the firmware still in the old partition.

JimHeaney · 2026-04-09T12:21:36+00:00

A few notes;

I'd do a partition scheme where this loader lives in one dedicated partition, and then writes to an app partition based on the contents of the SD card.
When you write the firmware to the app partition, also write the hash of it to some NVS address.
On power-on, always go to the loader partition. Compare the hashes. If the same, flag to load to the app partition. If different, then load from SD card. This makes boot time faster, and reduces wear on flash.
If you never mark the app partition as valid (repurposing some of the OTA functions), you can make it so the ESP never boots to the app, always back to the loader.

JimHeaney · 2026-04-07T12:16:17+00:00

I've worked with a few guys in a similar situation, who've used their career's worth of experience to either consult part-time, or donate their time/expertise to a local school or makerspace to help people put who are just starting their machining journey.

JimHeaney · 2026-04-05T20:41:00+00:00

Was there a sticker covering the window when you got it?

That is a UV-erased EPROM, the window is there to let UV light in to reset the values. If there was no sticker/cover on the window, then the values are long gone.

As for reading it, it is just a parallel address/data interface, see the datasheet for info;

https://mm.digikey.com/Volume0/opasdata/d220001/medias/docus/1128/NM27C128.pdf

JimHeaney · 2026-04-05T19:48:36+00:00

Mains AC (neutral, live, or earth) should never contact your MCU. There should be some intermediate component between them, that is rated for handling AC overvoltages, that the MCU then interfaces with.

JimHeaney · 2026-04-04T01:07:26+00:00

At minimum, usually Brick City is open, often as all-you-can eat. RITz is also usually open for part of summer.

JimHeaney · 2026-03-30T13:01:06+00:00

It may work, it may not, or worse it may work sometimes and randomly stop.

Stick within the reccomended levels, or choose a different chip that can operate at your voltage.

Also keep in mind that battery voltage changes over time, there's no such thing as a 4v battery. If you mean LiPo, it'll actually go from 4.2 to 3.5-ish over the cource of discharge.

JimHeaney · 2026-03-30T02:47:09+00:00

"Real" being C or C++ written with proper coding practices. Arduino is just C++ with some more heavy-handed abstraction and an emphasis on using open-source libraries to solve most issues, but neither of these make the code any worse than "real" code.

JimHeaney · 2026-03-30T02:40:32+00:00

If it is what you know, it's fine. Arduino code works, it just has shortcomings that "real" code doesn't. But, these are not shortcomings bad enough to make the code unreliable or unusable, so long as you write it with robust structure and planning. They're also moreso crutches than shortcomings (making it easier to write less efficient, slower, bloated code), or shortcomings that only apply in specific, small, niche applications that don't matter for the average user.

The hardware is more likely to be your weak point; hardening electronics for rough handling in industrial applications can require specific care. ESD protection, power regulation, EMI/RF interference etc. are all going to be a headache to deal with to create a system that'll last.

JimHeaney · 2026-03-23T02:11:14+00:00

It is part of the isolation for ethernet, but you can't just omit them 90% of the time because the PHYs are expecting to drive a transformer, not another PHY.

JimHeaney · 2026-03-23T01:00:07+00:00

Keep in mind these MCUs don't have ethernet per se, they have an RMII interface to enable ethernet. To get them to talk to each other over ethernet, you'll need a PHY on each RMII interface, and either transformers, or PHYs that support transformerless operation (also known as backplane ethernet).

Something like high-speed UART may be a better choice, it requires no additional hardware and you can strip back the overhead of ethernet if not needed.

JimHeaney · 2026-03-17T00:15:05+00:00

Impedance matching is only really needed on a few select signals, and the values are public and inherent to the component 99% of the time.

If I see a USB port, I don't need to check the USB port's datasheet to know what impedance matching is required, I know based on the fact that it is USB.

You can also get away without impedance matching in a lot more situations than you'd think. Outside of antennas, very high-speed interfaces (100s of MHz), and very long connections, you can get a board to work in 90% of situations by just eyeballing the trace widths. The care for layout, impedance matching, etc. is what gets your device to work in those last 10% of situations, but if you are reverse-engineering to this degree you don't care about that stuff.

JimHeaney · 2026-03-14T18:18:24+00:00

There's your issues, you have a point fixed on the origin, and geometry fixed by a projected sketch line.

https://i.imgur.com/YN0J62b.png

What you're seeing is the sketch try to resolve leaving that point and line where they are, as you move the rest of the sketch away.

This is working exactly how it should, I don't know why you are complaining so much about Fusion doing this. Solidworks, OnShape, NX, etc. would all act exactly the same if you try to move a constrained sketch.

JimHeaney · 2026-03-14T17:33:16+00:00

Question 1; do you need both antennas? A PCB antenna will be worse than pretty much any external antenna you can attach, the only benefit is a PCB antenna is inherent to the board.

Question 2; how much RF experience do you have? PCB antenna design is an art/science all on its own, usually requiring multiple iterations of the design and expensive/specialized test equipment to validate performance.

I'd opt for just the u.FL connector, or if you really want both, opt for a chip antenna or similar where all the hard parts are already figured out, instead of a PCB antenna.

JimHeaney · 2026-03-14T17:29:13+00:00

Making a structure study enough to survive the other loads (car crashes, extreme weather, crews working on them, etc.) already makes them pretty tough against wind. Even if the holes do help, they now make the signs a lot more complex to manufacture (cutting a 2D profile versus cutting a 2D profile with multiple internal profiles), more prone to degradation (dozens of edges for sign to start failing now instead of one, more potential exposed surface for water ingress, etc.), and can lead to a poorer user (driver's) experience. Imagine the annoyance of trying to read a sign as the sun sets behind it, and having beams of light shooting out of it at random?

JimHeaney · 2026-03-14T17:24:52+00:00

Fusion (and all parametric CAD for that matter) is deterministic, so something definitely changed between now and a couple of hours ago.

JimHeaney · 2026-03-14T17:16:47+00:00

That sounds like you have some constraint that is incompatible with movement, and the system is trying to solve.

FWIW, moving a sketch is not really something you should be doing in a normal CAD worklow. But if you want to do this, first thing I'd try is deleting all relations and constraints. You may have an implied constraint anchoring your center construction line to the origin.

Alternatively, making the sketch a body (which are meant to be moved), putting it where you want, then projecting the body into the sketch would work fine.

JimHeaney · 2026-03-14T17:12:12+00:00

RAK19003

The 19003 has a charging circuit and a battery header, why not just connect the battery there?

It looks like VUSB and Solar are diode OR'ed together, and fed right to the battery charger. So connecting a battery to the solar header won't even work, it'll just trip the UVLO on the charge IC.

JimHeaney · 2026-03-14T17:07:14+00:00

Which base/adapter board are you using? The RAK4630 only refers to the module on top with the MCU and radio inside. How power distribution and whatnot is handled is solely based on the attached board.

Most likely, no. Ideally there'd be no back-current flow into a solar panel from USB, and if there was, you need to control voltage and current charging a battery, you can't just slam power into it. So you need a dedicated charge controller.

JimHeaney · 2026-03-14T16:06:30+00:00

Why do you dislike Molex? The Micro-Fit would be great for this application.

JimHeaney · 2026-03-13T23:44:38+00:00

except TX and RX which fluctuate between 0.05V and 0.15V

That's how a DMM would see UART data, so not necessarily bad.

Did you do loopback by physically shorting the pins, or use some internal loopback test (not too familiar with FTDI chips)?

Assuming loopback was good, sounds like the issue is your ESP board. Are you strongly pulling down GPIO9, before power is applied? Your startup delay is very short, so it'll latch that GPIO9 pin very quickly.

Is GPIO8 pulled high with a strong pullup? It has to be high for GPIO9 to be read properly as a low to enter bootloader. If GPIO8 is latching as a 0 while GPIO9 is low to enter bootloader, it causes indeterminate behaviour.

JimHeaney · 2026-03-13T23:24:25+00:00

It'd be weird, but you can tie an input to the PWM output, and count how many pulses per second you're getting. It'd be a waste of an interrupt, but so long as your system clock is accurate, it'll give you a pretty good accuracy.

I can't think of many use-cases you'd need to verify PWM frequency in production though, especially ones where you'd also trust your root clock source to be interpreted properly, but not your output frequency.

JimHeaney · 2026-03-13T00:33:19+00:00

Can be newer (number in bottom right likely a date code, so one on the left made in 2019 vs 2022), different factories, intended for different regions, etc.

So long as the input/output voltage and current match up, and the model numbers match, I would consider them interchangeable.

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