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Quorten Blog 1

First blog for all Quorten's blog-like writings

Wow, I found an interesting FPGA Raspberry Pi Zero HAT on Digi-Key, Ice Zero with Lattice ICE (ICE40HX).

20191128/https://www.digikey.com/product-detail/en/trenz-electronic-gmbh/TE0876-02/1686-1162-ND/9816551
20191128/https://media.digikey.com/pdf/Data%20Sheets/Trenz%20Electronic%20PDFs/TE0876-02_Web.pdf

This gets me thinking, I’ve got to consider designing my Raspberry Pi Zero main board to also feature an “GPIO direct expansion slot” similar to the PDS expansion slot on the Macintosh SE, just for the sake of attaching these very interesting Raspberry Pi Zero HATs when I also have other stuff in a larger system to attach.

Many PCB board markings are self-explanatory, R = resistor, C = capacitor, D = diode. But there are also many obscure PCB markings, such as U = integrated circuit, L = inductor, Q = transistor. That being said, I found a StackExchange question with a good reference for these marking abbreviations.

20191127/DuckDuckGo Q2 PCB marking
20191127/https://electronics.stackexchange.com/questions/25308/what-do-the-pcb-markings-mean
20191127/https://blogs.mentor.com/tom-hausherr/blog/tag/reference-designator/

Also, it’s something to keep in mind if you design your own printed circuit boards, what markings you should use for the components on your board.

Wow, it’s finally coming here, for real! The GitHub Archiving program, an initiative to save all public code repositories on GitHub to the Arctic World Archive (AWA) on microfilm. Yes, this is it, a testament to those who truly value what matters has the will to preserve it long-term, using the best-of-trade tools. Yep, this is real, this is also a really good point for emphasizing the value of software with non-technical family and friends.

20191127/https://archiveprogram.github.com/

This Bloomberg Businessweek article includes more pictures of what the inside of the Arctic World Archive looks like.

20191119/https://www.bloomberg.com/news/features/2019-11-13/microsoft-apocalypse-proofs-open-source-code-in-an-arctic-cave

And here is a LinkedIn post that includes a video taken during a previous GitHub Arctic Code Vault deposit.

20191210/https://www.linkedin.com/posts/github_less-than-a-month-left-to-get-your-code-into-activity-6623701717680824320–MPm

Which repositories are included? Any repository that has been recently updated in the past couple of months.

There is also a lesser valuable initiative, in my experience, to archive data onto a Quartz disc using a laser. Come on, we know that is pretty esoteric compared to microfilm, how is a naive human who has little interest in the sophistication of the technology, let alone little monetary resources of their own, expected to read and comprehend anything out of such a form?

What polyfuse should be used with Raspberry Pi Zero in a larger board circuit? Look to the Raspberry Pi B+ or original Raspberry Pi schematics for guidance. Then, you simply search around for a part with similar specifications to use in your own circuit. One design note in particular, you should place the polyfuse immediately after your power input source. Your first isolating capacitor should come after the polyfuse.

20191127/DuckDuckGo raspberry pi zero polyfuse
20191127/https://raspberrypi.stackexchange.com/questions/61302/does-raspberry-pi-zero-have-a-polyfuse

In particular, the MF-MSMF200 is used on the Raspberry Pi A+, a 2 A hold polyfuse with 4 A trip.

20191128/https://www.raspberrypi.org/documentation/hardware/raspberrypi/schematics/rpi_SCH_1aplus_1p1_reduced.pdf

The original Raspberry Pi used a 750 mA hold polyfuse with 1.1 A trip.

20191128/https://elinux.org/RPi_HardwareDuckDuckGo raspberry pi polyfuse
20191128/https://www.element14.com/community/thread/19575/l/f1f2-polyfuses-gone
20191128/https://elinux.org/RPi_Hardware

Now, this is a great Digi-Key article on diodes, in particular I find the coverage of Schottky diodes most interesting. Schottky diodes have a low forward voltage drop which makes them great for use in power supplies, for protecting against reverse polarity, and protective diodes in inductor/motor circuits. Also included is a great schenatic on how to use a voltage regulator chip, LM2595. Alas, that’s only a buck switching power supply, it doesn’t have boost capability. Nonetheless, it’s a high frequency switching regulator, which allows for smaller sized filter components.

20191127/https://www.digikey.com/en/articles/techzone/2019/nov/the-fundamentals-application-of-zener-pin-schottky-varactor-diodes
20191127/https://www.digikey.com/product-detail/en/texas-instruments/LM2595SX-ADJ-NOPB/LM2595SX-ADJ-NOPBCT-ND/3440112

Okay, so I think I’ve found a few good candidates. First of all, though, some design considerations on the Raspberry Pi Zero power supply. Although you can run the Raspberry Pi Zero off of 3.3 V power, keep in mind (at least to be safe) that the limit of 1 A of power consumption still applies. In other words, that means that you can only distribute about 66% of the maximum power when running 3.3 V power into the 5 V connector, effectively limiting the max power consumption to “660 mA at 5 V” (3.3 Watts). Yeah, that’s good enough to run the Raspberry Pi Zero at full CPU load plus Raspberry Pi camera (500 mA at 5 V), a good handful of LEDs (max 242 mA at 3.3 V), but basically nothing else. But, of course, you can’t run USB devices anyways unless you give a full 5 V power supply.

Read on →

What is a service mesh?

2019-11-27

Categories: kubernetes  
Tags: kubernetes  

What is a service mesh? This is a great article that explains service meshes.

20191126/https://servicemesh.io/

Now, for a discussion in my own words. Basically, a service mesh allows you to throw more stuff onto the technology heap without rearchitecting the whole system. Definitely not a good idea if you are designing a small systems project, but like many other similar technologies, this facet makes it wildly popular in the large complicated software systems sector of modern cloud computing, enterprise back-end, etc.

For quite a while, I despised the fact that surface-mount assembly prototyping required you to do your own solder paste and pick and place the components by band. Alas, I was merely short-sighted. Searching around on the Internet, I came upon this site, JLCPCB(JiaLiChuang (HongKong) Co., Limited). They do in fact provide fully automated assembly of printed circuit boards, including pick and place for surface-mount devices. Ball-grid array assembly is not supported, though. Still, come on, that’s pretty good!

20191125/https://jlcpcb.com/v
20191125/https://support.jlcpcb.com/article/13-who-is-jlcpcb
20191125/https://support.jlcpcb.com/category/78-smt-assembly
20191125/https://support.jlcpcb.com/article/83-smt-assembly-faqs
20191125/https://support.jlcpcb.com/article/79-pick-place-file-for-smt-assembly
20191125/https://support.jlcpcb.com/article/80-bill-of-materialsbom-file-for-smt-assembly

Interesting that they’ve only been around for 12 years. “Only” 12 years? Come on, that’s a long time! In the tech world in general, yeah, but they are relatively young compared to other companies in their area of electronics prototyping/manufacturing support companies such as Digi-Key, Mouser, etc. Then again, PCB manufacturing service companies seem to be rather young… many of the old big electronics businesses did the whole process in-house. So in that respect, they are old for a PCB manufacturing services company.

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Interesting, a C64 BASIC program found on a Christian rock band vinyl record. Good to know that they were sufficiently into programming back them to get around to pulling off that trick. Nowadays it seems that kind of thing is much rarer in popular culture, especially smaller sub-segments and sub-cultures therein.

20191125/https://hackaday.com/2019/11/24/secret-c64-program-found-on-a-christian-rock-bands-vinyl-record/

`setsid` to run SSH with custom password

2019-11-26

Categories: unix  
Tags: unix  

Want to be able to run ssh and pass a password directly into it? That is a bit challenging, but totally doable. First of all, write your own SSH_ASKPASS that basically responds to the password prompt by echoing the password to standard output. Set that in the SSH_ASKPASS environment variable, then call setsid with your ssh command. ssh will then see that there is no connected controlling terminal and proceed to use SSH_ASKPASS to get the password.

When typing numbers with unit, should there be a space or no space between the units? I have seen both conventions to varying degrees. In general, it is more formal to type a space between units, ideally a non-breaking space, with only a few exceptions, but many times in conventional and informal use, numbers are typed without a space to separate the units.

20191125/DuckDuckGo space or no space between units
20191125/https://english.stackexchange.com/questions/2794/punctuation-with-units