Lack Of Space Is No Longer An Excuse For Not Having A Pen Plotter

July 27, 2019 by Jenny List 26 Comments

Pen plotters, those mechanical X-Y drawing machines that have in many cases been superseded by inkjet and other printer technologies, exert a fascination from a section of our community. Both analogue and digital machines are brought out of retirement for some impressive graphical effects, and we suspect that more than one of you wishes you had the space for one in your lives.

The good news is that you now no longer need room for a hefty piece of 1970s instrumentation, because the ever-inventive [Bart Dring] has produced a tiny 3D-printed plotter with an ESP32 at its heart. The ESP runs his ESP32 port of the Grbl firmware, and can handle a G-code file placed wirelessly upon the controller’s SD card.

The mechanism is particularly clever, using a single belt for both X and Y axes. The pen lift Z axis is a hinged design rather than a linear one, with a hobby servo doing the lifting. The hinge bearings are placed as close as possible to the paper surface to achieve an approximation to a vertical lift. You can see the machine in action in the video below the break, drawing its own self-portrait.

If you are a long-time reader you will recognise [Bart]’s work, he has appeared here quite a few times. His coaster-cutting machine and his CNC plotter badge are particularly memorable.

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High-Tech Alms Collection With The ESP32

July 17, 2019 by Tom Nardi 2 Comments

In an ideal world, shop space, tools, and components would be free. But until we get to that Star Trek utopia, hackerspaces will have to rely on donations from the community to help stay afloat. While asking for money, at least you can have some fun with it if you design and build an Internet-connected donation box.

Or at least that’s how [Goran Mahovlic] handled it for the Radiona hackerspace in Zagreb, Croatia. Not content with just cutting a slit in the top of a shoe box, he came up with a physical donation system that’s not only more informative for those donating, but more organized for those collecting the funds.

The key is a arcade-style programmable coin acceptor from SparkFun. When connected to a microcontroller, this allows the box to keep a running tally on how much money has been inserted. With the use of a RFM96 LoRa module, it can even report on the current haul while remaining mobile; perfect for when the hackerspace has events outside of their home base.

But counting quarters is hardly a task befitting a powerful microcontroller like the ESP32. So [Goran] gave the chip something to do in its spare time by adding a couple of buttons and an LCD. This allows the user to scroll through a list of various projects that are looking for donations, and decide which one they want to financially support. When the donation box counts how much money has been inserted, it records which project its been earmarked for.

Of course, if you’d rather the free market do its thing, we’ve seen this same coin acceptor used to build a locker-sized vending machine. Or if you’re feeling crafty, you could always try your hand at building one with cardboard.

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A Wedding Gift Fit For A Hardware Hacker

July 13, 2019 by Jenny List 7 Comments

If you read Hackaday on a regular basis, there are some names you will have seen more than once. People who continually produce fascinating and inventive projects that amaze and delight us, and who always keep us coming back for more. One such hacker is [Jeroen Domburg], perhaps better known in these pages by the handle [Sprite_TM], who has never failed to delight us in this respect.

Today is a special day for [Jeroen] for it is his wedding day, and his friend [Maarten Tromp] has decided to surprise him and his wife [Mingming] with a special gift. At first sight it is simply a pair of blinky badges in the shape of a bride and groom, but closer examination reveals much more. The PCBs are studded with WS2812 addressable LEDs controlled by an ESP32 module and powered by a small LiPo battery, and the clever part lies in the software. The two badges communicate via Bluetooth, allowing them to both synchronise their flashing and flash ever faster as the couple come closer to each other.

The write-up is an interesting tale of the tribulations of designing a badge, from which we take away that buying cheap LEDs may be a false economy. A surprise was that the black-cased and white-cased versions of the LEDs had different timings, and they proved prone to failure.

We wish the happy couple all the best, thank [Sprite_TM] for all he has given us over the years, and look forward to seeing his future projects.

New Part Day: The $15 ESP32 With Cellular

July 9, 2019 by Brian Benchoff 51 Comments

Cruise around AliExpress for long enough and you’ll find some interesting new hardware. The latest is the TTGO T-Call, an ESP32 breakout board that also has a cellular modem. Yes, it’s only a 2G modem, but that still works in a lot of places, and the whole thing is $15.

On board the TTGO T-Cal is the ESP-WROVER-B, the same module you all know and love that features a dual-core ESP running at 240 MHz with 4 MB of Flash and 8 MB of SRAM. Add to this WiFi and Bluetooth, and you have a capable microcontroller platform. Of note is that this board includes a USB-C port, ostensibly wired so that it behaves like a normal USB micro port. That’s neat, 2019 is the year USB C connectors became cheaper than USB micro connectors.

In addition to the ESP32 module, there’s also cellular in the form of a SIM800 module. This module has been around for a while and used in many, many cellular-connected projects and products like the ZeroPhone. This module is only a 2G module, and that’ll be going away shortly (if not already) in built-up areas, but this can serve as a building block for modules that have more Gees than a 2G module. That said, if you’re looking for a WiFi and cellular bridge for fifteen bucks, you could do a lot worse for a lot more money.

ESP32 Gets Advance Windowed Apps Using This VGA GUI Library

July 8, 2019 by Ted Yapo 38 Comments

We featured [Fabrizio Di Vittorio]’s FabGL library for the ESP32 back in April of this year. This library allows VGA output using a simple resistor based DAC (3 resistors for 8 colors; 6 resistors for 64 colors), and includes functions for PS/2 mouse and keyboard input, a graphics library, and many of the miscellaneous functions you might need to develop games on the ESP32. Now, a GUI interface library has been added to ease application development.

The GUI, of course, runs on the VGA output. The library includes what you’d expect from a minimal windowing GUI, like keyboard and mouse support, windows with the usual minimize/maximize/close controls, and modal and message dialog boxes. For input controls, there are labels, text boxes, buttons, radio buttons, checkboxes, normal and editable combo boxes, and listboxes — you know, pretty much everything you need to develop a modern GUI application. All the code is open-source (GPL 3.0) and in the GitHub repo.

While the original FabGL had a game-development orientation, the addition of this new GUI functionality opens up a new range of applications. If you want to find out more about using the FabGL library, you can check out our previous coverage of the mostly game-oriented functions.

You can get a look at the new GUI functions in action in the video, after the break.

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Hacked Calipers Make Automated Measurements A Breeze

July 4, 2019 by Dan Maloney 22 Comments

Now, digital calipers with wired interfaces to capture the current reading are nothing new. But the good ones are expensive, and really, where’s the fun in plugging a $75 cable into a computer? So when [Max Holliday] was asked to trick out some calipers for automating data capture, he had to get creative.

[Max] found that cheap Harbor Freight digital calipers have the telltale door that covers a serial connector, making them a perfect target for hacking. A little Internet sleuthing revealed the pinout for the connector as well as some details on the serial protocol used by most digital calipers: 24-bit packets is six four-bit words. [Max] used his SAM32, a neat open-source board with both a SAMD51 and an ESP32 that can run CircuitPython. An inverting buffer interfaces the serial lines to the board, which is just the right size to mount on the back of the caliper head. It’s hard to tell how [Max] is triggering readings, but the SAM32 is mounted as a USB device and sends keystrokes directly to a spreadsheet – yes, with the ESP32 it could have been wireless, but his client specifically requested a wired setup. Taking multiple readings is easy now that the user never has to swap calipers for a pen.

Cheap calipers like these are pretty hackable – you can add Bluetooth, turn them into DROs for a milling machine, or even make them talk.

Dry Your Boots With The Internet Of Things

June 24, 2019 by Lewin Day 16 Comments

If you live somewhere cold, where the rain, snow and slush don’t abate for weeks at a time, you’ve probably dealt with wet boots. On top of the obvious discomfort, this can lead to problems with mold and cause blisters during extended wear. For this reason, boot dryers exist. [mark] had a MaxxDry model that had a timer, but it wasn’t quite working the way he desired. Naturally, it was begging to be hooked up to the Internet of Things.

The brains of the dryer is an ESP32, a solid choice for such a project. With WiFi on board, connecting the device to the internet is a snap. Relays are used to control the fan and heater inside the boot dryer, while MQTT helps make the device controllable remotely. It can be manually switched on and off, or controlled to always switch on at a certain time of the day.

It’s a simple project that shows how easily a device can be Internet controlled with modern hardware. For the price of a cheap devboard and a couple of relays, [mark] now has a more functional dryer, and toasty feet to boot.

We don’t see a lot of boot hacks here, but this magnet-equipped footwear is quite impressive.