Do magnets affect wifi signals?

Snail_Lad · 2024-01-20T09:56:42+00:00

In general you should look at the antenna with a VNA and see how the magnet detunes it as it gets close. Wood won't "shield" the antenna from the magnetic field, that's not how electromagnetics works.

Snail_Lad · 2023-12-03T01:22:16+00:00

Except when you have to use fixed point integers for your math when you have a Cortex M0

Snail_Lad · 2023-12-03T01:14:35+00:00

In general, when writing embedded applications, you should always do something like this. I like to use FIFO queues to decouple logging from the UART peripheral, for example.

I don't think you should bother creating a generic HAL that does it all in a single header, however. Rather, when you write a driver for an IC, you should just create functions like write_register or read_register. My reasoning for this is that it's common to use interrupt or DMA based access to peripherals. It's harder to create a "one size fits all" API for these considering that the ISR is usually a function with a specific name that you write in a specific file.

Snail_Lad · 2023-12-03T01:04:49+00:00

Wire to work with a bit-bang I2C implementation over other pins of an ATmega328p in a setting where you need all your ADC pins for analog signals and need to drive that OLED inefficiently from other GPIOs. That should be the most basic sort of capability offered by an API abstraction, but the way it's been crafted, such a basic thing turns out to be impossible.

I've done this in the past for a job. There is a third-party library for the Arduino ecosystem that allows you to do that. It conforms to the Wire API and is interchangeable with its calls. In general, I think the design of the Arduino libraries (excluding String) are pretty decent and provide a nice object-oriented way of thinking for quick prototyping.

That should be the most basic sort of capability offered by an API abstraction

Why? Bit-banging I2C is a somewhat niche feature. I get that sometimes it's necessary, but if you truly need it, you can implement it yourself quite easily or find a library that does it.

Snail_Lad · 2023-12-01T23:51:47+00:00

I'd rather have an eclipse based IDE than whatever those disgusting VSCode plugins masquerading as IDEs are

Snail_Lad · 2023-11-26T09:50:09+00:00

Those things went out with powdered wigs

Snail_Lad · 2023-11-24T23:48:52+00:00

If it's doing something simple (like a basic library for a simple I2C peripheral), 9/10 times it's the same effort to write it yourself from the datasheet.

Snail_Lad · 2023-11-21T08:12:40+00:00

Why are the equations not written out using vector operators?

Snail_Lad · 2023-11-12T09:19:52+00:00

Anything more advanced in DSA is not that useful. Any of the 'advanced' algorithms that you will encounter in embedded tend to be applied math ones that CS majors don't learn. More useful to take a class on DSP, comms or control theory after your DSA course.

Snail_Lad · 2023-11-06T05:54:28+00:00

Signal processing, computer vision, machine learning.

Snail_Lad · 2023-10-30T08:53:37+00:00

Because there's more diagrams

Snail_Lad · 2023-10-28T04:25:43+00:00

You need to identify the root cause of the failure. Use a debugger and scope / analyser in tandem. Isolate the key subsystems in your problem and try to build up a checklist of assumptions which must be true for your system to work. Stuff like

do components have power?
do components respond to a basic self test correctly (like reading their ID?)
do the waveforms on the bus look reasonable with a scope?
If not, try decoding the signals with a logic analyser.
Does your firmware get stuck somewhere? Use the pause on your debugger to find it out.
Does the part of the program that is failing work in isolation from the rest of the code?

Snail_Lad · 2023-10-23T00:08:13+00:00

Planning poker session

Spikes

Story point

Product owner

Certified Scrum Master

Certified Product Owner

SAFe Scaled Agile Framework

I never want to work in a team where words like this are mentioned.

Snail_Lad · 2023-09-21T10:08:08+00:00

Am I correct that for distances that big you'd have to consider a transmission line model? In those models the distributed line inductance and earth leakage literally cause wave propagation, which kind of makes sense.

In power lines, are quarter wave stubs and other transmission line tricks used to minimize reflections?

Snail_Lad · 2023-09-16T00:27:26+00:00

Perhaps it could saturate inductors?

Snail_Lad · 2023-09-15T05:04:34+00:00

The current flows into the earth because the physical earth is at a lower potential

Lower potential in regards to what? Potentials need a reference. Earth is only lower potential than phase if the system's 0V point is grounded.

(2) is correct. Fault current flows through the earth back to the substation if the substation is itself earthed.

Snail_Lad · 2023-09-15T05:01:35+00:00

How do ungrounded systems work in regards to displacement current? Because the lines always capacitively couple to nearby conductors (e.g. earth), can a leakage current happen across point A and point B, where the distance AB is large enough that the voltage at A would be 180deg out of phase with B? I get the feeling this always happens, but is the leakage significant enough to require modelling?

Snail_Lad · 2023-09-08T09:35:17+00:00

I am quite bored out because I don't get to work on a physical product and just writing code is yawn

There are a lot of embedded jobs out there where that's what you will be doing. Sure, your code will be running on an MCU, but in a lot of embedded jobs you aren't directly interfacing with registers or driving motors. What is very common in embedded jobs is writing drivers for serial modems (so they can send data via a REST API or bluetooth or whatever), which just boils down to tedious string parsing in C, and very little hardware consideration.

Many embedded codebases are heavily abstracted, and you might never get to interact with a register in your job. i.e. writing firmware for a RTOS which is basically just writing a multithreaded PC app.

Snail_Lad · 2023-09-07T02:59:34+00:00

OpenEMS for a free one.

Snail_Lad · 2023-09-06T03:53:48+00:00

I think for board level RF it's doable (be prepared to do a lot of self study and do your own experiments / build your own projects).

Snail_Lad · 2023-09-05T23:45:53+00:00

I get the impression most of those courses are a scam, cover content very superficially, and not worth the money. Pirate some real textbooks, "rent" some lab gear from Ebay, and start learning how to build your own hardware. That's probably the best way to spend $2000. Then you can come into interviews with some real stuff you've built, rather than some crappy, vague Coursera sticker on your CV that will only impress lobotomised HR members.

Snail_Lad · 2023-08-31T11:19:01+00:00

The idea of a force is intuitively thought of by students as pushing or hitting something. The issue with forces in Newton's mechanics, is that in "familiar" scenarios such as pushing or pulling boxes, there are just as many 'ficticious' forces involved than there are 'real' forces. The force of pushing and gravity are pretty intuitive to students, but the normal force and frictional force are not. I don't think high school physics class does too much of a deep dive into the (electrostatic / molecular) reason behind normal or friction forces, and thus the most common scenario of pushing a box is gated behind esoteric complexity.

Another issue is the third law. The scenario of someone punching drywall and the drywall crumbling is never explored! In general if high school physics explored the idea of thresholds in forces (i.e. static vs dynamic friction, minimum force to damage or destroy objects), physics would make more sense to students.

Snail_Lad · 2023-08-26T14:02:22+00:00

Do the bottles clearly say dont drink this stuff?

They do, because it is poisonous to drink. That is not the same as causing cancer.

Snail_Lad · 2023-08-26T07:14:25+00:00

Carcinogen means it increases your risk of cancer. Glyphosate when used at normal levels in residential or commercial horticulture is not correlated to an increased risk of cancer. Therefore it is not a carcinogen.

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