Benchmarking Latency Across Common Wireless Links For MCUs

February 11, 2024 by 13 Comments

Although factors like bandwidth, power usage, and the number of (kilo)meters reach are important considerations with wireless communication for microcontrollers, latency should be another important factor to pay attention to. This is especially true for projects like controllers where round-trip latency and instant response to an input are essential, but where do you find the latency number in datasheets? This is where [Michael Orenstein] and [Scott] over at Electric UI found a lack of data, especially when taking software stacks into account. In other words, it was time to do some serious benchmarking.

The question to be answered here was specifically how fast a one-way wireless user interaction can be across three levels of payload sizes (12, 128, and 1024 bytes). The effective latency is measured from when the input is provided on the transmitter, and the receiver has processed it and triggered the relevant output pin. The internal latency was also measured by having a range of framework implementations respond to an external interrupt and drive a GPIO pin high. Even this test on an STM32F429 MCU already showed that, for example, the STM32 low-level (LL) framework is much faster than the stm32duino one.

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Resistor Color Code Clock Is A Bit Of Fun

February 3, 2024 by 6 Comments

Younger electronic engineers may see resistors with old-style color codes to display their values a little less than those from previous years, but if there’s a shibboleth among those who wield a soldering iron it’s probably something similar to instinctively saying “1K” when asked “Brown-black-red?”. Colors as numbers can be used outside resistors, for example in a clock, as [Det Builds Stuff] shows us with an ESP32 TFT dev board.

It’s fair to say that this is more of a software project than a hardware one, but that’s not necessarily a bad thing as he takes us though the process of creating a Network Time Protocol (NTP) capable clock with the dev board. He claims it may be the world’s first resistor clock, something we’d have to disagree with, but beside that we can see this could make a neat little desk ornament with a 3D printed case.

Oddly though, we’d expect older engineers to face the same steep learning curve as younger ones when reading it, because it’s easier to recognize visual sequences of numbers as preferred resistor values than it is to visually decode each one every time.

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Bus Pirate 5 Now Shipping

January 25, 2024 by 34 Comments

It’s happened to all of us at one time or another. There’s some component sitting on the bench, say an I2C sensor, a new display, or maybe a flash chip, and you want to poke around with it. So you get out the breadboard, wire it to a microcontroller, write some code, flash it…you get the idea. Frankly, it’s all kind of a hassle. Which is why [Ian Lesnet] created the Bus Pirate: a USB multi-tool designed to get you up and running with a new piece of hardware as quickly as possible.

Now, after years of development, the Bus Pirate 5 is available for purchase. Completely redesigned to take advantage of the impressive I/O capabilities of the RP2040, the new Bus Pirate also features a 240 x 320 IPS LCD that can show real-time voltage data and pin assignments. But despite the new display, and the bevy of RGB LEDs lurking under the injection molded enclosure, the primary interface for the device remains the VT100 terminal interface — now with the addition of a color status bar running along the bottom.

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Reverse-Engineering The Web-@nywhere Watch For 2001-Era Smartwatch Action

January 21, 2024 by 10 Comments

Although smartwatches seem to be just a recent fad, people have been strapping wristwatches to their wrists with all kinds of functionality. Whether a miniscule calculator, a remote control, an organizer or as in the case of the Web-@nywhere Watch a web browser. In the last case only sort of, naturally, as it was released in 2001 and this little early 2000s marvel cost only $85 (or $150 in 2024 USD), so what could it really be capable of? This is the million dollar question that [Cameron Kaiser] sought to find out as he found a new-in-box unit for sale.

The Web-@nywhere watch in action. (Credit: Cameron Kaiser)
The Web-@nywhere watch in action. (Credit: Cameron Kaiser)

Beforehand he knew already that the unit required interaction with a PC-based application to sync the 93 kB of on-watch data, with the required software and remote servers now being very much outdated and/or gone. This required some reverse-engineering to once more bring this watch widget back to life. Along the way it became also quite clear that this watch was designed as a cheap rip-off of the much better 1998 Seiko Ruputer – which later got sold also as the onHand PC – using the same joystick-driven interface.

After some poking around with the Windows-based software that came with the watch [Cameron] quickly realized that while it could establish a serial link with the watch in its cradle, it fully relied on a now defunct FTP server formerly run by the manufacturer, Kinger, along with any games and content on it. Since FTP servers were never archived like HTTP sites, this content is likely gone forever.

Fortunately, the protocol between the PC and the watch is a standard serial link (with parity), so [Cameron] was able to sniff the serial traffic and figure out the protocol, the results of which he has made available on GitHub in the form of a Perl script for transforming text and a C-based application to do the uploading. Now once again Web-@nywhere users can proudly roam the streets with 2024-era website content on their wrists.

Alarm Panel Hack Defeats Encryption By Ignoring It

January 19, 2024 by 23 Comments

As frustrating as it may be for a company to lock you into its ecosystem by encrypting their protocols, you have to admit that it presents an enticing challenge. Cracking encryption can be more trouble than it’s worth, though, especially when a device gives you all the tools you need to do an end-run around their encryption.

We’ll explain. For [Valdez], the encrypted communication protocols between a DSC alarm panel and the control pads on the system were serious impediments to integration into Home Assistant. While there are integrations available for these alarm panels, they rely on third-party clouds, which means that not only is your security system potentially telling another computer all your juicy details, but there’s also the very real possibility that the cloud system can either break or be shut down; remember the Chamberlain MyQ fiasco?

With these facts in mind, [Valdez] came up with a clever workaround to DSC encryption by focusing on physically interfacing with the keypad. The device has a common 16×2 LCD and a 25-key keypad, and a little poking around with a multimeter and a $20 logic analyzer eventually showed that the LCD had an HD44780 controller, and revealed all the lines needed to decode the display with an ESP32. Next up was interfacing with the keypad, which also involved a little multimeter work to determine that the keys were hooked up in a 5×5 matrix. Ten GPIOs on the ESP32 made it possible to virtually push any key; however, the ten relays [Valdez] originally used to do the switching proved unwieldy. That led to an optocoupler design, sadly not as clicky but certainly more compact and streamlined, and enabling complete control over the alarm system from Home Assistant.

We love this solution because, as [Valdez] aptly points out, the weakest point in any system is the place where it can’t be encrypted. Information has to flow between the user and the control panel, and by providing the electronic equivalents to eyes and fingers, the underlying encryption is moot. Hats off to [Valdez] for an excellent hack, and for sharing the wealth with the HA community.

Haier Threatens Legal Action Against Home Assistant Plugin Developer

January 19, 2024 by 109 Comments

Appliance manufacturer Haier has been integrating IoT features into their newer products, and as is so common these days, users are expected to install their “hOn” mobile application to access them. Not satisfied with that limitation, [Andre Basche] reverse engineered the protocol used by the app, and released a Python library and associated Home Assistant plugin to interface with a wide array of Haier appliances, which includes brands like Hoover, Candy, GE Appliances and others.

Unfortunately, it looks like his efforts have gotten him into a bit of legal hot water. In an issue recently opened on the project’s GitHub page, [Andre] explains the circumstances and legal options that have led him to consider pulling the repositories completely — mostly due to the cost of mounting a legal defense to the cease & desist from Haier Europe.

What’s ironic here is that Haier has been part of the Connectivity Standard Alliance (CSA) since 2022, whose goal is to ‘promote universal open IoT standards’, including Matter.

It’s possible that a legal defense will be mounted against this C&D from Haier within the coming days. Yet regardless of the outcome here, it remains problematic that these IoT-enabled Haier appliances are connected to the Haier servers. Ideally they would be controlled locally, which is the goal of projects like [Miguel Ángel López Vicente]’s ESP Haier, that uses an ESP8266 to connect Haier AC units to the local WiFi and e.g. HA instances, all without requiring internet access.

This is sadly just one more example of why building your own off-line smart home can be such an incredible struggle.

Thanks to [Ar3itrary] for the tip.

Remembering ISDN

January 15, 2024 by 89 Comments

We are definitely spoiled these days in terms of Internet access. In much of the world gigabit speeds are common and even cheap plans are likely to be measured in 100s of megabits. But there was a time not long ago when a fast modem received at 56 kilobits per second. If you couldn’t justify a dedicated T1 line and you had a lot of money, you might have thought about ISDN – the Integrated Services Digital Network. [Tedium] has a great retrospective now that the UK has decided to sunset ISDN in 2025. ISDN started in the UK in the mid-1980s.

ISDN offered two 64-kilobit channels that could be bonded to reach 128 kilobits. There was also a slower third channel for commands and signaling (although you could use it for data, too, using an X.25-like protocol). If you wanted phone service, your voice was on one 64K channel and the data on the other. No need to tie up your phone just to get online. Voice was digitized at 8 kHz with 8 bits of G.711 encoding.

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