GSG Interns

Please welcome the Great Scott Gadgets summer interns, Ellie Puls and Jacob Graves. They joined us at the beginning of June, and we are thrilled to have both of these bright students on our team. Ellie is a junior at CU Boulder and Jacob is a senior at CU Denver, and they are both majoring in Computer Science. They plan to write a short blog post every couple of weeks over the summer to let you know what they've been learning and what kind of projects they've been working on. Here's what they've been up to in their first couple...

Как работает лазерная рулетка: реверс-инжиниринг

Ранее в своей статье я рассказывал о том, как устроены фазовые лазерные дальномеры. Теперь пришло время разобраться с тем, как работают бытовые лазерные рулетки. Разобраться — это не просто заглянуть, что же там внутри, а полностью восстановить всю схему и написать собственную программу для микроконтроллера.
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Устранение дребезга контактов на основе вертикальных счетчиков

При разработке встраиваемых систем очень часто возникает необходимость в устранении дребезга кнопок или цифровых входов. Это можно сделать аппаратно, применив ФНЧ на входе, либо программным способом. Хорошо известен программный метод устранения дребезга одновременно на нескольких входах на основе вертикальных счетчиков. Несмотря на широкое распространение этого метода, очень часто в литературе он представлен без подробного объяснения принципа работы. Попоробуем объяснить работу вертикальных счетчиков более полно и доступно. Вам потребуется базовые знания двоичной арифметики и программирования на С/С++.

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Playing back GSM RTP streams, RTP-HR bugs

Chapter 0: Problem Statement

In an all-IP GSM network, where we use Abis, A and other interfaces within the cellular network over IP transport, the audio of voice calls is transported inside RTP frames. The codec payload in those RTP frames is the actual codec frame of the respective cellular voice codec. In GSM, there are four relevant codecs: FR, HR, EFR and AMR.

Every so often during the (meanwhile many years of ) development of Osmocom cellular infrastructure software it would have been useful to be able to quickly play back the audio for analysis of given issues.

However, until now we didn't have that capability....

Power-cycling a USB port should be simple, right?

Every so often I happen to be involved in designing electronics equipment that's supposed to run reliably remotely in inaccessible locations,without any ability for "remote hands" to perform things like power-cycling or the like. I'm talking about really remote locations, possible with no but limited back-haul, and a very high cost of ever sending somebody there for remote maintenance.

Given that a lot of computer peripherals (chips, modules, ...) use USB these days, this is often some kind of an embedded ARM (rarely x86) SoM or SBC, which is hooked up to a custom board that contains a USB hub chip as well as a line of peripherals.

One...

GSG is Hiring

Are you (or do you know someone who is) a match for our open position for a summer intern? See our new jobs page for details. Keep an eye on this page for future job opportunities at Great Scott Gadgets!

New MOnSter6502 updates, with video!

https://player.vimeo.com/video/217483777

It’s been a while since we’ve had an update to the MOnSter6502 project–we’ve been very busy getting the second revision ready. At the same time, I’ve been designing a simple yet powerful 6502-based computer that can operate at the slow clock speeds required by the MOnSter6502.

But before I go into detail about that, take a look at this video update. It’s one thing to see photos of the MOnSter6502, but the video really brings out just how awesome this thing is in person! (Shameless plug for Maker Faire Bay Area 2017 where you should come visit us.)

The MOnSter6502 runs up...

Overhyped Docker

Overhyped Docker missing the most basic features

I've always been extremely skeptical of suddenly emerging over-hyped technologies, particularly if they advertise to solve problems by adding yet another layer to systems that are already sufficiently complex themselves.

There are of course many issues with containers, ranging from replicated system libraries and the basic underlying statement that you're giving up on the system packet manager to properly deal with dependencies.

I'm also highly skeptical of FOSS projects that are primarily driven by one (VC funded?) company. Especially if their offering includes a so-called cloud service which they can stop to operate at any given point in time, or (more realistically) first...

OsmoDevCon 2017 Review

After the public user-oriented OsmoCon 2017, we also recently had the 6th incarnation of our annual contributors-only Osmocom Developer Conference: The OsmoDevCon 2017.

This is a much smaller group, typically about 20 people, and is limited to actual developers who have a past record of contributing to any of the many Osmocom projects.

We had a large number of presentation and discussions. In fact, so large that the schedule of talks extended from 10am to midnight on some days. While this is great, it also means that there was definitely too little time for more informal conversations, chatting or even actual work on code.

We also have such...

Book on Practical GPL Compliance

My former gpl-violations.org colleague Armijn Hemel and Shane Coughlan (former coordinator of the FSFE Legal Network) have written a book on practical GPL compliance issues.

I've read through it (in the bath tub of course, what better place to read technical literature), and I can agree wholeheartedly with its contents. For those who have been involved in GPL compliance engineering there shouldn't be much new - but for the vast majority of developers out there who have had little exposure to the bread-and-butter work of providing complete an corresponding source code, it makes an excellent introductory text.

The book focuses on compliance with GPLv2, which is probably not too surprising...