How to Easily Calibrate Retraction in 3D Printers

Retraction Calibration 3D Printers

Hey, Karl here with a short article on retraction tuning. I really enjoy reviewing 3D printers and all things 3D printing with one exception…. when I have to calibrate retraction (aka retraction tuning). It takes so much time. What is Retraction? While 3D printing on a standard FDM printer, the filament is pushed with an extruder motor that has a gear attached. It pushes the filament, either directly into the hotend assembly or through a Bowden tube to the hotend. Molten plastic is then layered to produce a model. When it is printing nearly all prints require non-extruding movements. During the extruding moves pressure builds up and in order to stop stringing and blobbing during non-printing moves, a retraction happens. There are 2 main variables that affect this: the speed it moves and the distance. In the past, I would take a calibration model and adjust these 2 variables and test. This can take a long time. First, I had …

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How to Sandbox an arm64 GCC on aarch64 Hardware with armv7 Userspace

Arm64 GCC Armv7 Userspace

CNXSoft: Guest post by Blu about setting up arm64 toolchain on 64-bit Arm hardware running a 32-bit Arm (Armv7) rootfs. Life is short and industry progress is never fast enough in areas we care about. That’s an observation most of us are familiar with. One would think that by now most aarch64 desktops would be running arm64 environments, with multi-arch support when needed. Alas, as of late 2019, chromeOS on aarch64 is still shipping an aarch64 kernel and an armhf userspace. And despite the fine job by the good folks at chromebrew, an aarch64 chromeOS machine in dev mode ‒ an otherwise excellent road-warrior ride, is stuck with 32-bit armhf. Is that a problem, some may ask? Yes, it is ‒ aarch64 is the objectively better arm ISA outside of MCUs, from gen-purpose code to all kinds of ISA extensions, SIMD in particular. That shows in contemporary compiler support and in the difference in quality of codegen. Particularly with the …

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Using Sony PS3 Eye Camera as an Inexpensive Microphone Array

PS3 Eye

Almost exactly two years ago to the day, we published an article showing how microphone arrays performed against a single USB microphone, and the latter started to have a poor wake word detection success rate at around 3 meters array even in a silent room, and it got worse with white noise or background music, while the microphone arrays would pick up the wake word with a much higher success rate in all conditions. The price of smart audio development kits varies a lot from $500 for Intel Speech Enabling Developer Kit to $129 for an Allwinner R18-based 3-Mic Far-Field Amazon AVS Development Kit, and $99 for ReSpeaker Core v2. If you’ve already got a Raspberry Pi 3/4 board, you can get cheaper options such as ReSpeaker 4-Mic Array for $25, but nothing beats the price of Sony PS3 Eye camera that comes with a 4 microphone array and sells on Amazon for around $7.5. You may even already have …

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Getting Started with ANAVI Gas Detector Starter Kit and Home Assistant

ANAVI ESP8266 Gas Detector Display

ANAVI Gas Detector is an ESP8266 based board designed for MQ gas sensors supported by Arduino. This allows you to easily monitor air quality, or more accurately air conductivity using MQ-135 sensor as part of the starter kit either visually on the OLED display, or through your smartphone or computer using MQTT via automation platform such as Home Assistant. Leon Anavi sent me an ANAVI Gas Detector Starter Kit to have a look, and I’ll report my experience with the kit using it standalone, and through Home Assistant. Starter Kit Unboxing The kit contains the open-source hardware, ESP8266 based ANAVI Gas Detector board, a plastic stand, an OLED display, a USB to serial adapter, a gas sensor, and a few KiCad and ANAVI stickers. The board itself comes with an ESP8266MOD module, features a micro USB port for power, a reset button, four LEDs, a UART console, a 4-pin GPIO header, three I2C headers for sensors, a 4-pin connector for …

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Getting Started with Sipeed M1 based Maixduino Board & Grove AI HAT for Raspberry Pi

Grove AI HAT Face Detection

Last year we discovered Kendryte K210 processor with a RISC-V core and featuring AI accelerators for machine vision and machine hearing. Soon after,  Sipeed M1 module was launched with the processor for aroud $10. Then this year we started to get more convenient development board featuring Sipeed M1 module such as Maixduino or Grove AI Hat. Seeed Studio sent me the last two boards for review. So I’ll start by showing the items I received, before showing how to get started with MicroPython and Arduino code. Note that I’ll be using Ubuntu 18.04, but development in Windows is also possible. Unboxing I received two packages with a Maixduino kit, and the other “Grove AI HAT for Edge Computing”. Grove AI HAT for Edge Computing Let’s start with the second. The board is a Raspberry Pi HAT with Sipeed M1 module, a 40-pin Raspberry Pi header, 6 grove connectors, as well as connectors for camera and display. The USB-C port is …

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Wear Estimation for Devices with eMMC Flash Memory

flash wear leveling & garbage collection

CNXSoft: This is a guest post by Marcel Ziswiler, Platform Manager – Embedded Linux, Toradex and Leonardo Graboski Veiga, Technical Marketing Engineer, Toradex related to Marcel’s upcoming talk “Wear Estimation for Devices with eMMC Flash Memory” at the Embedded Linux Conference 2019 later this month. Flash memory has been an important topic in embedded systems for decades. It allows for drastic improvements to the size and robustness of electronic devices compared to other storage technologies. Other benefits of flash storage include a lack of moving parts and reduced power consumption. However, the challenges that come with flash memory are not as widely publicized in consumer electronics. Among them are limited durability and greater software complexity. As shown in Figure 1, flash memory is everywhere in our daily lives, ranging from devices used specifically to store data, such as thumb drives, SD cards and SSDs, to other consumer electronics that use it internally, like smartphones, Wi-Fi modems and smart light bulbs. …

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MINIX NEO S2 USB-C SSD Hub Review in Ubuntu 18.04 with Khadas Edge

MINIX NEO S2 Khadas Edge

MINIX NEO S1 & S2 are USB-C hubs with the usual HDMI and USB outputs, but also a built-in 120 GB & 240 GB SSD respectively. The company has sent me a sample of each, and in order to test the platform, I decided to do on a Khadas board running Ubuntu 18.04 with LXDE desktop environment (aka Lubuntu). I’ll start by checking out the packages’ content, before going through my experience with the MINIX NEO S2 USB-C hub in Ubuntu 18.04 with LXDE desktop environment. MINIX NEO S1 & S2 Unboxing Both packages are basically identical except for the different color, and one shows 120GB SSD capacity, while the other has 240GB The back side has some more details about the USB-C hub. I’ll focus on the 240GB model since it’s just the same, but around $13 to $20 more expensive, and it offers double the capacity, as well as slightly higher performance. The USB-C hub ships with a …

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Reading ID Card Data in Ubuntu with EZ100PU Smart Card Reader (Thai ID Edition)

Smart Card Reader Thai ID Card

I was asked help with configuring a smart card reader on a government computer running Windows 7, but this made me wonder what would happen if I connected the card reader to my Ubuntu laptop and whether I’d be able to read content from a Thai ID card. EZ100PU Smart Card Reader Let’s have a look at the card reader itself first. It’s a FAST ID EZ100PU smart card reader compliant with ISO7816 standard. That’s the product page of the specific model, but a search for EZ100PU only reveals the manufacturer may be InfoThink Technology based on Taiwan. The USB smart card reader comes with a CD that includes drivers for Windows, Linux, Mac OS, and Android, as well as an SDK with a demo program and sample code in C++, Visual Basic .NET, and C#. As we’ll see further below, the Linux driver is not needed as it works out of the box. The design of the board (RX-N99B-2) …

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