Day: December 7, 2019

Using Glow-in-the-Dark Fish Gut Bacteria To Make Art

December 7, 2019 by 3 Comments

In New Orleans, a Loyola University professor has been creating original art out of glow-in-the-dark fish gut bacteria, enough to fill 1000 Petri dishes. Her first major foray into art was biomorphic abstractions, inspired by Impressionist painters, with her current work reflecting much of the abstraction of the earlier style.

The bacteria comes from the Pacific Rock Fish and glows a vibrant electric-blue. It is typically kept in a freezer and has a texture and color similar to water when it’s being used. The luminescence only lasts for 24 hours, presenting timing challenges when preparing artwork for a photoshoot, as artist [Hunter Cole] often does. With a Q-tip, [Cole] paints roses, lilies, and insects onto the Petri dishes and arranges them for surreal photography shoots. In addition to painting shapes in agar, she uses a light painting technique by filling clear water bottles with the bacteria for long-exposure shots.

[Cole] is planning on presenting her work at an art exhibit in New Orleans, along with showcasing a performance piece featuring models clad in chandelier-like costumes glowing with bioluminescent bacteria in petri dishes.

File Systems For Tiny Devices

December 7, 2019 by 11 Comments

Sometimes you build a computer and use it every day. Sometimes you build a different type of computer and it sits alone on a mountaintop for years. The design considerations for these two setups are remarkably different, right down to the type of file system used. For small computers like [Jo] is using, and for the amount of time they sit alone in remote locations, he decided to build his own file system for them.

Known as JesFs ([Jo]’s embedded serial File system), the file system is for SPI Flash and intended for use in scientific data logging. It can be used on the chip-scale processors found in many development boards, and is robust enough to use in applications where remoteness is a concern. It has a small RAM footprint, is completely open source, includes wear leveling, and has a number of security features built-in as well.

Some of the benefits of using a file system on such a tiny chip aren’t immediately obvious unless you’re doing a lot of data logging, but it does allow you to change virtually any aspect of the firmware much more easily if everything is accessible as a file, and not something you would have to change by reflashing the whole chip, for example. There are also a number of traps that you can easily fall into when working with file systems for tiny devices.

ESP32 Audio Sampling With Interrupts And IRAM

December 7, 2019 by 9 Comments

Interrupting while someone is talking is rude for humans, but smart for computers. [Ivan Voras] shows how to use interrupts to service the ESP32 analog to digital converters when sampling sound. Interestingly, he uses the Arduino IDE mixed with native ESP-IDF APIs to get the best performance.

Like most complex interrupt-driven software, [Ivan’s] code uses a two-stage interrupt strategy. When a timer expires, an interrupt occurs. The handler needs to complete quickly so it does nothing but set a flag. Another routine blocks on the flag and then does the actual work required.

Because the interrupt service routine needs to be fast, it has to be in RAM. [Ivan] uses the IRAM_ATTR attribute to make this work and explains what’s going on when you use it.

…the CPU cores can only execute instructions (and access data) from the embedded RAM, not from the flash storage where the program code and data are normally stored. To get around this, a part of the total 520 KiB of RAM is dedicated as IRAM, a 128 KiB cache used to transparently load code from flash storage.The ESP32 uses separate buses for code and data (“Harvard architecture”) so they are very much handled separately, and that extends to memory properties: IRAM is special, and can only be accessed at 32-bit address boundaries.

This is very important because some ESP-IDF calls — including adc1_get_raw — do not use this attribute and will, therefore, crash if they get pushed out to flash memory. At the end, he muses between the benefit of using an OS with the ESP32 or going bare metal.

If you want to know more about the Arduino on ESP32, we covered that. We also dug deeper into the chip a few times.

Learn Water Purification Techniques With This STEM Learning Kit

December 7, 2019 by 7 Comments

We see a lot of great STEM education projects. These projects have a way of turning into something much larger. How many commercial devices and machines are built on Raspberry Pi’s and Arduinos? [Ryan Beltrán] is using common materials to teach people how to clean water. This particular kit demonstrates a water purification process called electro-coagulation.

When current is passed through two electrodes suspended in water it changes the surface charge on the suspended solids. This causes the solids, metals, and oils to clump together which makes them considerably easier to treat and clean.

The kit consists of a jar, electrodes, some 3D printed parts, and a pre-flashed Arduino. There’s also salts and filters to finalize the purification process. Students can start the experiment right away and if they’re inspired they’ll have all the tools to try more advanced techniques.

Often STEM kits lean heavily to robotics or computer science, but there are so many vast and interesting fields out there with problems that need to be solved.

The HackadayPrize2019 is Sponsored by:

Beer Keg Becomes High-Performance Pizza Oven

December 7, 2019 by 14 Comments

Pizza varies all around the world, with several cities having put their own mark on the Italian dish. To make an authentic pie in the Neapolitan style requires extremely high temperatures in order to cook the pizza through in just a couple of minutes. Armed with a beer keg and some ingenuity, [AndrewW1977] got down to work, building a rig that could get the job done.

The build starts by cutting the keg in half. A series of zigzag steel pieces are welded inside, in order to give the refractory cement more surface area to stick to. With the cement poured and set, a handle was welded to the keg for ease of use, as well as a thermometer to monitor internal temperatures.

Initial attempts to cook using the rig used a wood-fired rocket stove design. This had the drawback of taking up to 45 minutes to reach the appropriate temperature, so the build then switched to using God’s Gas, clean burning propane, as a fuel source. With a jet-style burner installed in the base, the oven was ready to start turning out pizzas.

The idea of cooking a hot, fresh pizza in just a couple of minutes has us salivating at the possibilities. We’ve seen other high-speed pizza ovens, too. Video after the break.

Continue reading “Beer Keg Becomes High-Performance Pizza Oven” →

Upgrade Your Shades To Find Lost Items

December 7, 2019 by 8 Comments

Ever wish you could augment your sense of sight?

[Nick Bild]’s latest hack helps you find objects (or people) by locating their position and tracking them with a laser. The device, dubbed Artemis, latches onto your eyeglasses and can be configured to locate a specific object.

Images collected from the device are streamed to an NVIDIA Jetson AGX Xavier board, which uses a SSD300 (Single Shot MultiBox Detection) model to locate objects. The model was pre-trained with the COCO dataset to recognize and localize 80 different object types given input from images thresholded in OpenCV. Once the desired object is identified and located, a laser diode activates.

Probably due to the current thresholds, the demo runs mostly work on objects placed further apart against a neutral background. It’s an interesting look at applications combining computer vision with physical devices to augment experiences, rather than simply processing and analyzing data.

The device uses two servos for controlling the laser: one for X-axis control and the other for Y-axis control. The controls are executed from an Adafruit Itsy Bitsy M4 Express microcontroller.

Perhaps with a bit more training, we might not have so much trouble with “Where’s Waldo” puzzles anymore.

Check out some of our other sunglasses hacks, from home automation to using LCDs to lessening the glare from headlights.

Continue reading “Upgrade Your Shades To Find Lost Items” →

Simple Pogo Programmer For ESP8266 Modules

December 7, 2019 by 19 Comments

ESP8266 development boards like the Wemos D1 Mini and NodeMCU are an excellent way to get a one-off project up and rolling quickly, but their size and relative complexity mean they aren’t necessarily a good choice for even short-run production hardware. On the other hand, programming the bare ESP modules can be something of a pain. But thanks to [Greg Frost], flashing those tiny little boards just got a lot easier.

His 3D printed design uses pogo pins to securely connect to the board’s castellated edges, which also holds it in place during the programming process. On the back side there’s just a few jumper wires and a couple of resistors, which ultimately lead to the FT232R FTDI board that actually connects the chip to the computer so you can program it.

We’d like to see a back panel that encloses the wiring, and perhaps an alternate version that deletes the space for the FTDI board in favor of a row of header pins. Both easy enough modifications to the basic design should [Greg] or anyone else feel so inclined. But even as it is, this is a great little programmer that can be sourced and assembled easily and cheaply.

This isn’t the first 3D printed ESP8266 programmer we’ve seen, and there are some improvised versions which are even cheaper to put together, but this design has a certain professional look that we think will be right at home on your bench.