prbs23 (u/prbs23) - Readit News

prbs23 commented on Free LoRaWAN Books univ-smb.fr/lorawan/en/fr... · Posted by u/teleforce

bb88 · a year ago

The big problem with LoRa today is that in some places, the typical frequencies you can use for LoRa (915MHz in the US) are saturated with traffic. Also LoRa literally is Long Range, and those IoT packets might be heading out >1 mile from your house easily.

It will work when n==1, but not when n==1000 in a square mile, say. Given that, I would certainly be trimming back on the power so it doesn't transmit more than 500 feet out of your house. I've had a heltec Meshtastic receiver broadcast about 2 miles line of sight easily.

And then there's the whole thing about encryption, since your packets can travel miles, and your devices can receive packets from miles away...

prbs23 · a year ago

As long as you are using the LoRaWAN protocol (not just LoRa modulation), encryption is not optional. It's built into the link layer of LoRaWAN, and a device cannot join a network without a unique key that's shared out of band.

Also, the range is entirely the point of using LoRaWAN for some of us. All other IoT protocols have an abysmally short range, making them impractical for anything other than single building applications. Maybe most don't need a mile of range, but the fact that it can reach across a couple of acres enables a lot of applications.

prbs23 commented on Show HN: Smelt — an open source test runner for chip developers silogy-io.github.io/smelt... · Posted by u/1024bees

prbs23 · a year ago

Interesting concept for a project... From what I have seen in the industry, it seems like this is something every organization ends up developing at least one custom tool for. EDA vendors even generally sell their own solution to this problem, but we always end up back at custom tools. It would be interesting to see if community collaboration could find a better general solution.

That said, it seems like Smelt is far too early in development to be practically used at this point. Some basic table stakes that I didn't see:

- Test weighting. Having a way to specify a relative repeat counts per test is essential when using constrained random tests like we do in the ASIC world.

- Some form of tagging to identify a test as belonging to multiple different groups. When combined with a way to intersect and join groups when specifying the tests to run.

- Control over the random seed for an entire test run. I was glad to see some support for test seeds. However when invoking smelt to run multiple tests, it would be nice to be able to reproducibly seed the generation of each individual test seed. Maybe this is outside the scope of this project?

Great things to see:

- Procedural test generation is a key feature.

- Extendable command invocation

- SLURM support is in the roadmap, also an important feature for groups that use SLURM.

prbs23 commented on Agilent 2000a / 3000a Oscilloscope NAND Recovery salvagedcircuitry.com/200... · Posted by u/sharpshadow

prbs23 · 2 years ago

This is an awesome write up!

I have one of these scopes, with exactly this issue after a long period in storage. When I was looking into it a few years ago the failure mode was known but I couldn't find a recovery procedure. I'll need to give this a try when I get a few hours. I have been putting off getting a new scope in hopes that I could repair this issue.

prbs23 commented on Machine learning helps fuzzing find hardware bugs spectrum.ieee.org/hardwar... · Posted by u/rbanffy

prbs23 · 2 years ago

I don't understand why fuzzing hardware is being presented as a new thing here... In silicon validation, constrained random testing has been the standard methodology for at least 10 years. With the complexity of modern CPUs, it's effectively impossible to validate the hardware _without_ using some kind of randomized testing, which looks a whole lot like fuzzing to me. What is new here? Or is this a case of someone outside the industry rediscovering known techniques.

prbs23 commented on Ask HN: Could you share your personal blog here? · Posted by u/revskill

prbs23 · 2 years ago

https://www.prbs23.com/blog/

Started a couple years ago, but I don't have as much time to write as I'd like. The majority of topics relate to ASIC design and verification, since that is my day job, but with some other side projects mixed in.

prbs23 commented on Ask HN: Most interesting tech you built for just yourself? · Posted by u/l2silver

prbs23 · 3 years ago

I rewrote the UI for an off the shelf WiFi digital photo frame so that it shows the latest raw images sent back from the Perseverance Mars rover. https://prbs23.com/blog/posts/picture-frame-from-mars/

The picture frame secretly ran Android under the hood. Which meant I could replace the app which showed pictures pulled from the manufacturers server, with one which pulls photos from the NASA website. Fortunately they left ADB enabled with root permissions, so it was trivial to replace their startup app with my own. All the source code is public here: https://gitlab.com/prbs23/mars-photo-stream

prbs23 commented on “Open source” seeds loosen Big Ag’s grip on farmers worldsensorium.com/open-s... · Posted by u/dnetesn

davexunit · 3 years ago

My favorite seed seller, Fedco, has an OSSI section: https://fedcoseeds.com/seeds/list-ossi

I have tried and liked Dazzling Blue Kale and Gildenstern Lettuce. I'm trying out some other OSSI lettuce varieties this year, of which there are many.

prbs23 · 3 years ago

If you are interested in more OSSI varieties like those, check out Wild Garden Seed: https://www.wildgardenseed.com

The owner, the Frank Morton who was mentioned in article, is the original breeder of both Gildenstern and Dazzling Blue (and they probably grew the seed being sold by Fedco). All the varieties he bread (of which there are many) are released as OSSI varieties, plus they sell other OSSI varieties as well.

prbs23 commented on Git security vulnerabilities announced github.blog/2023-01-17-gi... · Posted by u/ttaylorr

CorrectHorseBat · 3 years ago

Your could use interrupts, no? Basically free when not triggered and when triggered you probably don't care about performance anymore.

prbs23 · 3 years ago

Most architectures do not provide an interrupt that is generated by an integer overflow. Since this would be a significant architectural change in the hardware, it can't be simply added in.

Additionally, if you are running inside an operating system, handling an interrupt usually incurs a trip through the kernel, which would add extra overhead every time an overflow did happen. Since there's a lot of software which depends on integers overflowing, this overhead on each overflow could significantly impact legacy software.

prbs23 commented on Building a private LoRa network (2017) os.mbed.com/docs/mbed-os/... · Posted by u/Tomte

prbs23 · 3 years ago

I somewhat recently blogged about my process of setting up a private LoRaWAN network as well.

https://prbs23.com/blog/posts/getting-started-with-a-private...

LoRaWAN is definitely an interesting mix of open source implementations and open specifications, and proprietary poorly documented hardware. Unfortunately I haven't had time lately to actually use my network for anything real.