Making SVD Files Searchable With Svd2db

November 21, 2022 by Maya Posch 11 Comments

Everyone who writes bare-metal code for microcontrollers probably know the joys of looking up the details of specific registers in the reference manual, including their absolute address. Although the search function of the PDF viewer can be helpful, it’d be rather nice if there was a way to search only the registers, and have the offset calculations performed automatically. This is basically what [Terry Porter]’s Svd2db tool enables. As the name suggests, this tool turns the SVD hardware description files that come with ARM-based MCUs into a database file.

This database file is an SQLite database, which allows it to be searched using the provided readdb tool, or any other SQLite tool. This would make the utility useful not just for quick look-ups during development, but presumably also for automated testing scenarios where having an easily searchable database of registers is of use. At this point Svd2db is guaranteed to work with STM32 SVDs, but may work with SVDs for other ARM-based SVD files as well.

Making A Do-It-Yourself Sand Battery

November 21, 2022 by Maya Posch 96 Comments

Storing energy can be done in many ways, with the chemical storage method of a battery being one of the most common. Another option is a thermal battery, which basically means making something hot, and later extracting that heat again. In this video by [Robert Murray-Smith] the basic concept of a thermal battery that uses sand is demonstrated.

By running a current through a resistive wire that’s been buried inside a container with sand, the sand is heated up to about 200 °C. As [Robert] points out, the maximum temperature of the sand can be a 1000 °C or more. Because sand doesn’t boil like water, the total amount of energy stored in sand is correspondingly higher.

Extracting the thermal energy can be done rather inefficiently using the demonstrated Peltier element. A Stirling engine, or steam generator and turbine, would get a lot more energy out. Either way, the thermal battery itself is made using just plain sand, which makes it an attractive DIY target to tinker with.

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FDA’s Approval Of Cell Culture Chicken: The Rise Of Fresh Meat Without The Animal?

November 21, 2022 by Maya Posch 105 Comments

On November 14th of this year, the FDA cleared the path for Upside Foods to sell its cell-culture-based chicken products within the US. This is the first product of its kind to be cleared for commercial sale within the Americas, with only Singapore having previously cleared a similar product for sale, back in December of 2020. This latter product comes courtesy of another California start-up called Eat Just.

Since that initial approval in Singapore, Eat Just has begun to set up a 2,800 square meter (~30,000 square feet) production facility in Singapore that is scheduled to begin producing thousands of kilograms of slaughter-free meat starting in the first quarter of 2023. This would make it the top-runner in the cultured meat industry, which to this point has seen dozens of start-ups, but precious few actual products for sale.

With CEO Josh Tetrick of Eat Just projecting price equality between their cultured meat and meat from animals by 2030, could the FDA’s approval herald the dawn of slaughter-free meat? There are obviously still hurdles, but as we’ll see, the idea is not nearly as far-fetched as one might think.

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On Getting A Computer’s Attention And Striking Up A Conversation

November 14, 2022 by Maya Posch 17 Comments

With the rise in voice-driven virtual assistants over the years, the sight of people talking to various electrical devices in public and in private has become rather commonplace. While such voice-driven interfaces are decidedly useful for a range of situations, they also come with complications. One of these are the trigger phrases or wake words that voice assistants listen to when in standby. Much like in Star Trek, where uttering ‘Computer’ would get the computer’s attention, so do we have our ‘Siri’, ‘Cortana’ and a range of custom trigger phrases that enable the voice interface.

Unlike in Star Trek, however, our virtual assistants do not know when we really desire to interact. Unable to distinguish context, they’ll happily respond to someone on TV mentioning their trigger phrase. This possibly followed by a ludicrous purchase order or other mischief. The realization here is the complexity of voice-based interfaces, while still lacking any sense of self-awareness or intelligence.

Another issue is that the process of voice recognition itself is very resource-intensive, which limits the amount of processing that can be performed on the local device. This usually leads to the voice assistants like Siri, Alexa, Cortana and others processing recorded voices in a data center, with obvious privacy implications.

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PCB antenna rendered useless by overly enthusiastic copper fill.

The Many Ways You Can Easily Ruin Your PCB Antenna Design

November 1, 2022 by Maya Posch 28 Comments

PCB antenna impaired by copper fill and other attenuation sources.

We have all seen Printed Circuit Board (PCB) antennas: those squiggly bits of traces on PCBs connected often to a Bluetooth, WiFi or other wireless communication chip. On modules like for the ESP8266 and ESP32 platforms the PCB antennas are often integrated onto the module’s PCB, yet even with such a ready-made module it’s possible to completely destroy the effectiveness of this antenna. These and other design issues are discussed in this article by [MisterHW].

It covers a range of examples of poor design, from having ground fill underneath an antenna, to having metal near the antenna, to putting dielectric materials near or on top of the antenna. The effect of all of these issues is generally to attenuate the signal, sometimes to the point where the antenna is essentially useless.

Ultimately, the best PCB antenna design is one where there is no nearby copper fill, and there are no traces running near or on layers below the antenna. After all, any metal trace or component is an antenna, and any dielectric materials will dampen the signal. Fortunately, there is e.g. a free KiCad library with ready-to-use PCB antenna designs to help one get started with a custom design, as well as many other resources, covered in the article.

If you want to get really professional about checking the effectiveness of an antenna design, you’ll want to use a Network Vector Analyzer. These will also help you with tuning the capacitors used with the PCB antenna.

(Featured image: PCB antenna rendered useless by overly enthusiastic copper fill.)

DeltaPen: Drawing, Painting And Taking Notes Without The Drawing Tablet

November 1, 2022 by Maya Posch 25 Comments

Over the decades, a lot of attempts have been made to try and make pens and pencils “smart”. Whether it’s to enable a pen to also digitally record what we’re writing down on paper, to create fully digital drawings with the haptics of inks and paints, or to jot down some notes on a touch screen, past and present uses are legion.

DeltaPen internal components and their function. (Credit: SIP, Guy Luethy et al.)

Where SIP Lab’s DeltaPen comes in as an attempt at a smart pen that acts more like the pen of a drawing tablet, just minus the tablet.

This project is related to the decidedly more clumsy Flashpen which we featured previously. Due to the use of new flow sensors, the underlying surface (e.g. a desk) can be tracked without needing to be level with it, which allowed for the addition of a pressure-sensitive tip.

In addition the relative motion of the pen is measured, and there is haptic feedback, which allow for it to be used even for more delicate applications such as drawing. The results of trials with volunteers across a range of tasks is described in their presented paper (PDF).

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Bare-Metal STM32: Setting Up And Using SPI

October 24, 2022 by Maya Posch 52 Comments

The Serial Peripheral Interface (SPI) interface was initially standardized by Motorola in 1979 for short-distance communication in embedded systems. In its most common four-wire configuration, full-duplex data transfer is possible on the two data (MOSI, MISO) lines with data rates well exceeding 10 Mb/s. This makes SPI suitable for high-bandwidth, full-duplex applications like SD storage cards and large resolution, high-refresh displays.

STM32 devices come with a variable number of SPI peripherals, two in the F042 at 18 Mb/s and five in the F411. Across the STM32 families, the SPI peripheral is relatively similar, with fairly minor differences in the register layout. In this article we’ll look at configuring an SPI peripheral in master mode.

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