Time Sync Through Your VGA Connector

November 10, 2019 by Jenny List 16 Comments

While it might be in its twilight years, the venerable VGA video connector conceals a versatile interface that can still provide the experimenter with the opportunity for a variety of hacks. We’ve not seen anything quite like [flok]’s one, in which he uses the VGA interface to insert timing information from which an NTPd instance gets its reference.

If this seems counter-intuitive because a VGA interface is an analogue output rather than a digital input, then you are correct to smell a rat. And he comes clean in his first sentence, as he’s not using the VGA lines themselves but the I²C interface that is a feature of all but the most basic of VGA cards. This is the means by which a plug-and-play operating system can identify a monitor’s capabilities, but there’s little to stop it being used for other purposes. In this case an Arduino fed by a 1-pulse-per-second timing signal from a temperature compensated crystal oscillator provides the I²C peripheral which is polled by NTPd.

This project should be of interest to any tinkerer because of its invaluable information on identifying and using the I²C interface on a VGA socket. So if you’ve used your VGA card as an SDR you might find it interesting, but hurry or you could have missed the boat entirely.

VGA plug image: Swift.Hg [CC BY-SA 3.0]

USB Power Delivery For All The Things

October 18, 2019 by Tom Nardi 25 Comments

The promise of USB Power Delivery (USB-PD) is that we’ll eventually be able to power all our gadgets, at least the ones that draw less than 100 watts anyway, with just one adapter. Considering most of us are the proud owners of a box filled with assorted AC/DC adapters in all shapes and sizes, it’s certainly a very appealing prospect. But [Mansour Behabadi] hasn’t exactly been thrilled with the rate at which his sundry electronic devices have been jumping on the USB-PD bandwagon, so he decided to do something about it.

[Mansour] wanted a simple way to charge his laptop (and anything else he could think of) with USB-PD over USB-C, but none of the existing options on the market was quite what he wanted. He looked around and eventually discovered the STUSB4500, a a USB power delivery controller chip that can be configured over I2C.

With a bit of nonvolatile memory onboard, it can retain its settings so he didn’t have to include a microcontroller in his design: just program it once and it can be used stand-alone to negotiate the appropriate voltage and current requirements when its plugged in.

The board that [Mansour] came up with is a handy way of powering your projects via USB-C without having to reinvent the wheel. Using the PC configuration tool and an Arduino to talk to the STUSB4500 over I2C, the board can be configured to deliver from 5 to 20 VDC to whatever device you connect to it. The chip is even capable of storing three seperate Power Delivery Output (PDO) configurations at once, so you can give it multiple voltage and current ranges to try and negotiate for.

In the past we’ve seen a somewhat similar project that used USB-PD to charge lithium polymer batteries. It certainly isn’t happening overnight, but it looks like we’re finally starting to see some real movement towards making USB-C the standard.

Introducing The First Cisco Certified Mixologist

October 4, 2019 by Tom Nardi 11 Comments

You’d be hard pressed to find an IT back office that doesn’t have a few Cisco routers or switches laying around and collecting dust. We’d even bet there are a decent number of people reading this post right now that have a stack of them within arm’s reach. They’re the kind of thing most of us have no practical application for, but we still can’t bear to throw away. But it looks like [Sven Tantau] has found an ideal middle ground: rather than junk his Cisco Catalyst switches, he turned them into automatic bartenders.

Inspired by all those perfect little square openings on the front, [Sven] loaded each switch with a whopping 24 peristaltic pumps, one for each Ethernet port. To fit all his plumbing inside, the switches were naturally gutted to the point of being hollow shells of their former selves, although he does mention that their original power supplies proved useful for keeping two dozen power-hungry motors well fed.

The motors are connected to banks of relays, which in turn are thrown by an ESP32 and an Arduino Nano. [Sven] explains that he wasn’t sure if the ESP32 could fire off the relays with its 3 V output, so he decided to just use an Arduino which he already knew could handle the task. The two microcontrollers work in conjunction, with a web interface on the ESP32 ultimately sending I2C commands to the Arduino when it’s time to get the pumps spinning.

[Sven] mentions his robotic bartenders were a hit at the 2019 Chaos Communication Camp, where we know for a fact the computer-controlled alcohol was flowing freely. Of course, if you don’t intend on carrying your barbot around to hacker camps, you can afford to make it look a bit swankier.

Continue reading “Introducing The First Cisco Certified Mixologist” →

Trill: Easy Positional Touch Sensors For Your Projects

September 16, 2019 by Ted Yapo 8 Comments

Creating capacitive touch-sensitive buttons is easy these days; many microcontrollers have cap-sense hardware built-in. This will work for simple on/off control, but what if you want a linear, position-sensitive input, like you’d find on a computer touchpad or your smartphone screen? Not so easy — at least until now. Trill is a family of capacitive touch sensors you can add to your projects as a linear slider, a square touchpad, or by creating your own touch surface.

Trill was created by the same team that designed Bela, an embedded platform for low-latency interactive applications, especially with audio. The new trio of Trill sensors rely on capacitive sensing to track finger movement, and communicate over I2C with your microcontroller or development board of choice. The Trill I2C library targets Arduino and Bela, but should be easy to port to any I2C host.

The hardware and software are both open-source — or will be as the Kickstarter that launched this morning has already met its goal. The firmware for the Cypress CY8C20636A (PDF) controller that powers these sensors will be released CC-BY-NC-SA. But, starting with the controller itself sounds like a lot of work that Trill has already done for you, so let’s have a look at what we know so far, along with a healthy dose of speculation.

Continue reading “Trill: Easy Positional Touch Sensors For Your Projects” →

PackProbe Reports Laptop Battery Health

June 26, 2019 by Lewin Day 11 Comments

The 18650 cell has become a ubiquitous standard in the lithium battery world. From power drills to early Tesla vehicles, these compact cells power all manner of portable devices. A particularly common use is in laptop batteries, where they’re often built into a pack using the Smart Battery System. This creates a smart battery that can communicate and report on its own status. PackProbe is a software tool built to communicate with these batteries, and you might just find it comes in handy.

The code runs on the WiFi-enabled Arduino Yún by default, but can be easily modified to suit other Arduino platforms. Communicating over SMBus using the Arduino’s I2C hardware, it’s capable of working with the vast majority of laptop batteries out there which comply with the Smart Battery System. With that standard being minted in 1994, it’s spread far and wide these days.

It’s a great way to harvest not only the specifications and manufacturing details of your laptop battery pack, but also to check on the health of the battery. This can give a clear idea over whether the battery is still usable, as well as whether the cells are worth harvesting for those in the recycling business.

You’re not limited to just the Arduino, though. There’s a similar tool available for the ESP8266, too.

Back To Basics With An Arduino And An EEPROM

May 25, 2019 by Jenny List 19 Comments

There are plenty of techniques and components that we use in our everyday hardware work, for which their connection and coding is almost a done deal. We are familiar with them and have used them before, so we drop them in without a second thought. But what about the first time we used them, we had to learn somewhere, right? [TheMagicSmoke] has produced just what we’d have needed then for one component that’s ubiquitous, the I²C EEPROM.

These chips provide relatively small quantities of non-volatile memory storage, and though they are not the fastest of memory technologies they have a ready application in holding configuration or other often-read and rarely written data.

Since the ST24C04 512-byte device in question has an I²C bus it’s a straightforward add-on for an Arduino Mega, so we’re shown the wiring for which only a couple of pull-down resistors are required, and some sample code. It’s not the most complex of projects, but it succinctly shows what you need to do so that you too can incorporate an EEPROM in your work.

If learning about I²C EEPROMs piques your interest, perhaps you’d like to read a previous look we made at them.

DIY Button Matrix Lights Up And Speaks I2C

May 17, 2019 by Donald Papp 2 Comments

[David Johnson-Davies] always wanted an illuminated button matrix for projects, but cost was never very friendly. That all changed when he discovered a cheap source of illuminated pushbuttons on Aliexpress, leading to this DIY 4×4 illuminated button matrix design which communicates over I²C. The button states can be read independently of setting the light pattern, and an optional interrupt signal gets pulled low whenever there is a change detected. Not bad for one PCB plus about $10-worth in components!

The device uses every single pin on an ATtiny88, and because each button gets its own pin the keypresses can be detected with pin-change interrupts. The state reporting of buttons over I²C is unambiguous, even when multiple buttons are pressed simultaneously. A simple protocol provides all the needed functionality, and all connections are brought to the board’s edge to allow for easily tiling multiple panels.

The GitHub repository contains the code and PCB files and [David] helpfully shared the board files to OSH Park and PCBWay for easy ordering. In addition, he provides two demos (Tacoyaki and Tacoyaki+) which are games related to the classic Lights Out to show off the matrix.