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Quorten Blog 1

First blog for all Quorten's blog-like writings

Raspberry Pi maximum voltage and TVS diode voltage regulator

quorten

2020-03-22

Categories: raspberry-pi  
Tags: raspberry-pi  

What is the maximum input voltage that Raspberry Pi can handle? 5.25 V is what is claimed to be the maximum. Beyond that, damage can result to your Raspberry Pi. Unless you have a Raspberry Pi 3, then it handles this in an interesting way… there is a TVS diode that will short if there is an overvoltage, and that will cause a high current that will trip the polyfuse, thereby preventing any damage from the overvoltage. Please note that your polyfuse’s max voltage should be above the clamping voltage of the TVS diode, else your polyfuse will get damaged before the TVS diode trips.

20200322/DuckDuckGo raspberry pi 5.2 maximum voltage
20200322/https://lb.raspberrypi.org/forums/viewtopic.php?p=1604897

So, what is a TVS diode? Ah, yes, the missing link that I was merely hinting at in my summary of protective circuits. Yes, indeed this is the missing link… if you want a semiconductor diode voltage regulator to provide a barrier against higher voltages in your circuit, but you want something that can specifically tolerate higher voltage transient spikes, a TVS diode will do that. A TVS diode is placed in reverse polarity in a circuit so it is normally non-conducting.

20200322/https://en.wikipedia.org/wiki/Transient-voltage-suppression_diode

Also related is a “crowbar device.” Unlike a TVS diode that dissipates much more excess energy as heat from itself, a crowbar device creates a short circuit path for the excess current to flow through.

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Interesting article about the end of Starsky Robotics autonomous trucking company

quorten

2020-03-21

Categories: random-software  
Tags: random-software  

This is an interesting article about the end of Starsky Robotics, an autonomous trucking company, and a view into the challenges of doing venture capital in that particular industry. My summary:

  • Trucking companies are not particularly tech-savvy when it comes to purchasing autonomous vehicles, therefore it makes more sense to run such a company as a trucking fleet business of its own.

  • Venture capital tech investors are not very savvy when it comes to safety engineering, but proper safety engineering is critical when it comes down to making ground in the autonomous trucking industry. Too often venture capital tech investors are more compelled by new features, not safety improvements and statements of fact that the delivered features will statistically function most of the time, not just some of the time.

  • Venture capital tech investors often times also don’t see companies individually, but see the sector as a whole. And when they feel the sector as a whole over-hyped, they will pull out of investing of all related companies, regardless of whether or not those particular companies were responsible for hyping.

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Some interesting Digi-Key blog articles

quorten

2020-03-21

Categories: raspberry-pi  
Tags: raspberry-pi  

Here are a few interesting Digi-Key blog articles that I’ve found. First of all, a nice review of some other small connectors that I am not familiar with, including water-resistant and dust-resistant variants.

20200321/https://www.digikey.com/en/articles/techzone/2015/sep/keeping-in-contact-miniature-connectors-that-can-take-the-strain

Next, an article about the up-and-coming standardized LED connectors for LED light bulbs.

20200321/https://www.digikey.com/en/articles/techzone/2014/feb/led-connectors-help-designers-meet-ssl-cost-performance-requirements

Here is an interesting blog article about 16-bit microcontrollers being an excellent sweep-spot between energy efficiency and computational power.

20200321/https://www.digikey.com/en/articles/techzone/2019/jul/take-advantage-of-16-bit-mcu-performance-and-low-power

Raspberry Pi maximum SPI clock speed, parallel ports, LPC bus delays

quorten

2020-03-20

Categories: raspberry-pi  
Tags: raspberry-pi  

Relating to using the pi-parport parallel port on the Raspberry Pi connected via SPI, one question that came up was the timing delays introduced via SPI serial communication may be unacceptable. Curious about this, I searched for information on the LPC (Low Pin Count) bus, which is a serial bus used to connect the Super I/O chip on early 2000s “Windows XP” era PCs. This is a 4-bit wide bus with a bus clock speed of 33.3 MHz, four times faster than the 16-bit parallel ISA at 8.33 MHz. On late 1990s “Windows 9x” era PCs, the Super I/O chip was connected via the 16-bit wide parallel ISA bus at 8.33 MHz bus clock speed, and there were also 24 parallel address lines at the same time.

A parallel port communication may involve sending or receiving an 8-bit data word and maybe an 8-bit/16-bit port number. So on the ISA bus, maybe this will take one bus cycle. But, it may take 4 bus cycles on the LPC bus. Nevertheless, the timing delay is comparable due to the higher bus clock speed.

20200320/https://en.wikipedia.org/wiki/Low_Pin_Count
20200320/https://en.wikipedia.org/wiki/Super_I/O
20200320/https://en.wikipedia.org/wiki/Industry_Standard_Architecture

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Inductors explained

quorten

2020-03-19

Categories: raspberry-pi  
Tags: raspberry-pi  

Okay, okay, so these ideas were coming from a larger documentation project I was working, but for the sake of timeliness and succinct containment, I thought I’d write a separate blog article on the subject.

What is an inductor? Basically, it’s kind of like a capacitor but the opposite in a few key ways. Both capacitors and inductors store energy. A capacitor stores energy in electric charge. An inductor stores energy in a magnetic field. As you know from the basic laws of electromagnetism, electric fields and magnetic fields go hand-in-hand with electromagnetic radiation. A changing electric field causes a changing magnetic field, and vice versa.

Okay, that all makes sense in concept, but what does this mean an inductor does in an electronic circuit? First of all, let’s review what a capacitor does in an electronic circuit. When a voltage source (i.e. battery) and a capacitor are connected, the capacitor will start charging up. Current will flow through the capacitor until it is charged up to the same voltage as the voltage source, at which point it will block the flow of current, i.e. it will resist the flow of current. Then, when the voltage source is disconnected, the capacitor will act like its own voltage source and supply current until it is fully discharged. Just like a battery, the voltage a capacitor supplies will gradually decay until it has no more charge left.

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Capacitors explained

quorten

2020-03-19

Categories: raspberry-pi  
Tags: raspberry-pi  

In the midst of trying to explain inductors, I realized that to be able to have a really good understanding of inductors, you need to have a really good understanding of capacitors. And, well, capacitors are quite tricky to properly understand, but they are somewhat easier to understand due to their similarity to batteries. But, the point is, amidst my attempt to explain inductors, I needed to have a clear explanation of capacitors. So here I am.

First of all, a very brief explanation of batteries as they relate to capacitors. Often times, a battery is modeled in a circuit simply as a fixed voltage source. The current in the circuit can then be computed using Ohm’s Law:

I = V / R

20200319/https://en.wikipedia.org/wiki/Ohm%27s_law

However, true batteries don’t last forever. Their lifetime is based off of how much electricity is consumed from them. Which is what? Intuitively, this is energy. For electricity, these are the pertinent equations:

E = P * t
P = V * I

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Golang package management and various module use information

quorten

2020-03-19

Categories: golang  
Tags: golang  

Here are my notes from today’s GoMN Meetup, this time being about various ways of doing Go Modules.

20200318/https://www.ardanlabs.com/blog/2017/02/package-oriented-design.html
20200318/https://changelog.com/gotime
20200318/https://www.youtube.com/watch?v=ik1l5a50hKQ
20200318/https://github.com/ardanlabs/gotraining
20200318/https://www.ardanlabs.com/ultimate-go/

20200318/https://github.com/hashicorp/vault/pull/8589

20200318/https://book.kubebuilder.io/

20200318/https://faasandfurious.com/122

20200318/https://github.com/golang/mock
20200318/https://golang.org/pkg/reflect/

20200318/https://nostarch.com/blackhatgo

20200318/https://grpc.io/
20200318/https://github.com/grpc/grpc-web
20200318/https://github.com/google/flatbuffers

20200318/https://google.github.io/flatbuffers/usergroup1.html

20200318/https://github.com/jesselang/presentations/blob/master/go-modules.md

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Moving from Win10 virtual machines to a physical machine

quorten

2020-03-18

Categories: windows  
Tags: windows  

Okay, previously I’ve covered how to install Windows 10 on a virtual machine. But, as things turned out, I ended up scaling up on Windows 10 rather than scaling down… so now I had to go through the ordeal of figuring out how to install Windows 10 on a physical machine. Here’s what I did.

First of all, I opted to use rewritable media… this meant there would be no DVD burning or the like. But this is where I was having trouble. First of all, modern Windows 10 images are big, 5+ GB. This makes them too large to write to a single-sided DVD, and also too large to write to many older USB stick flash drives. So… for my purposes, I had to resort to using an SD card.

Second… now this complication comes from using an older computer. The hardware could not boot off of an SD card directly, though it had an SD card reader. No worries, I had a USB SD card reader on hand, and doing that solved that problem.

Well… yes. The second problem is, of course, because I had an old laptop, I needed to make sure the image had an MBR boot record. This entailed rewriting the image from the ISO to the SD card using special software. My attempts at Linux-based software failed, so, lo and behold, I had to use my Windows 10 virtual machine to run the Rufus software to write out a proper Master Boot Record image.

20200318/https://en.wikipedia.org/wiki/Rufus_(software)
20200318/https://rufus.ie/

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More articles about the Coronavirus

quorten

2020-03-17

Categories: covid19  
Tags: covid19  

I’ve found this interesting article about the person who predicted the Coronavirus. What is the key predictor of zoonotic viruses transferring to humans? Humans encroaching on the existing natural ecosystem. When our population grows, and when we grow our livestock production from growth in purchasing power in the average household, we entrench deeper onto land that we’ve never been regularly frequenting before as humans. And when that happens, viruses that have been circulating throughout the natural environment long in advance have the opportunity to jump to our population and circulate within us. To say that this is predictable is like saying that it is predictable that without rules of the road, pedestrians would keep getting run over and killed by motor vehicles.

Right now, from a global standpoint, we don’t really have “rules of the road” laws and regulations across all governments how are land use is changing. Yes, there are some governments in first-world democracy countries that really do try to regulate what we do when we plan to change our land use, but there are still many dictatorship governments elesewhere in the world that wouldn’t care one bit about those who voice these concerns. And, of course, China is one of those countries.

20200317/http://nautil.us/issue/83/intelligence/the-man-who-saw-the-pandemic-coming?utm_source=pocket-newtab

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Digi-Key blog articles: isolation circuits, Raspberry Pi solar cells, and respect for power engineering

quorten

2020-03-16

Categories: raspberry-pi  
Tags: raspberry-pi  

Here are some useful and interesting blog articles from Digi-Key.

First, a good review and summary of power isolation circuits, I’ve got to keep this in mind:

  1. Inductive isolation via transformer coils, this is useful for transferring power but keeping the current loops separate.

  2. Opto-isolators. This is a fairly common traditional electrical isolation mechanism for data cables to prevent ground loops.

  3. Capacitive isolation. This is a somewhat newer method geared up for electrically isolating data connections, but it can be smaller and more tightly integrated than opto-isolation. Still, it can provide resistance for very high voltages.

Do keep in mind: The simplest way to transfer a digital signal across an electrically isolated gap is to use a modulated frequency for a one, and no current for a zero.

20200316/https://www.digikey.com/en/blog/engineering-and-isolation-its-not-what-you-think

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