Bare-Metal STM32: Blinky And The Secret Of Delay Functions

December 11, 2020 by Maya Posch 35 Comments

One of the very first examples for an MCU or SoC usually involves the famous ‘Blinky‘ example, where an LED is pulsed on and off with a fixed delay. This is actually a lot more complicated than the ‘Pushy‘ example which we looked at in the first installment of this series. The reason for this is that there’s actually quite a story behind a simple call to delay() or its equivalent.

The reason for this is that there are many ways to implement a delay function on a microcontroller (MCU), each of which comes with their own advantages and disadvantages. On an STM32 MCU, we get to choose between essentially an active delay (while loop), one implemented using the SysTick timer and using one of the peripheral timers. In the latter two cases we also have to use interrupts.

In this article we’ll take a look at all three approaches, along with their advantages and disadvantages.

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Remembering Chuck Yeager: The Supersonic Legend Whose Wings Were Clipped By A High School Diploma

December 10, 2020 by Maya Posch 37 Comments

In history there are people whose legacy becomes larger than life. Ask anyone who built and flew the first airplane, and you’d be hard-pressed to find someone who isn’t at least aware of the accomplishments of the Wright brothers. In a similar vein, Chuck Yeager’s pioneering trip into supersonic territory with the Bell X-1 airplane made his name essentially synonymous with the whole concept of flying faster than the speed of sound. This wasn’t the sole thing he did, of course: he also fought in WWII and Vietnam and worked as an instructor and test pilot, flying hundreds of different airplanes during his career.

Yeager’s insistence on making that first supersonic flight, despite having broken two ribs days earlier, became emblematic of the man himself: someone who never let challenges keep him from exploring the limits of the countless aircraft he flew, while inspiring others to give it their best shot. Perhaps ironically, it could be said that the only thing that ever held Yeager back was only having a high school diploma.

On December 7, 2020, Chuck Yeager died at the age of 97, leaving behind a legacy that will continue to inspire many for decades to come.

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Incredible Discrete MOSFET Rover Has Maximum Blink

December 4, 2020 by Maya Posch 12 Comments

What do you get when you stick 1738 MOSFETs together? If your answer was a ‘4-bit CPU’, you would be totally correct. Available as a product over at Marutsu as the ‘CPU1738’, it seems to target beginners to computer theory, with build instructions that explain how the CPU is built up from individual MOSFETs that are combined into logic gates.

While decidedly more compact in its SMD format than it would have been with pure through-hole parts, the use of countless small PCBs on top of the larger PCBs make for a pretty hefty package. Board after board build up the CPU, and the assembly continues with the addition of sensors, motors, and wheels. In the end, a robot emerges, albeit a somewhat wobbly-looking one.

Check out the video linked after the break, though before starting one up, note the 50,000 Yen (approximately $500) price tag for the CPU block alone. On the other hand, in addition to the 1738 MOSFETs, there are also 1070 LEDs, so you get what you pay for in blinkies.

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FTDI VCP Chips With Custom PIDs Not Working On MacOS 11 Big Sur

December 3, 2020 by Maya Posch 49 Comments

An anonymous reader pinged us about an issue that affects people who jumped onto the latest-and-greatest OS from the Apple gardens: USB devices that stop working due to the FTDI-based USB solution. At its core appears to be that the built-in FTDI driver provided by Apple (AppleUSBFTDI.dext) only supports FTDI chips which provide the standard FTDI vendor and product ID (e.g. 0x0403 and 0x6001 respectively for the FT232R). Many products however set a custom product ID (PID) to differentiate their device, though in the thread some mention that there are driver issues even with the default VID/PID combination.

Over the past years, Apple has been restricting and changing the way kernel extensions (KExt) and driver extensions (DExt) are handled. As these FTDI chips are often used for virtual com port (VCP) purposes, such as with Arduino boards and USB-TTL adapters, this is a rather cumbersome issue that would affect anyone using Big Sur in combination with such a hardware device.

So far only the FTDI team has been somewhat responsive based on the support forum thread, with Apple seemingly rather silent on the issue.

Game Cartridges And The Technology To Make Data Last Forever

December 3, 2020 by Maya Posch 69 Comments

Game cartridges are perhaps the hardiest of all common storage schemes. Short of blunt traumatic force or application of electrical surges to the cartridge’s edge connectors, damaging a game cartridge is hard to do by accident. The same is also true for the data on them, whether one talks about an Atari 2006 cartridge from the late 1970s or a 1990s Nintendo 64 cartridge.

The secret sauce here are mask ROMs (MROM), which are read-only memory chips that literally have the software turned into a hardware memory device. A mask layer unique to each data set is used when metalizing the interconnects during chip fabrication. This means that the data stored on them is as durable as the processor in the game console itself. Yet this is not a technology that we can use in our own hobby projects, and it’s not available for personal long-term data storage due to the costs associated with manufacturing what is essentially a custom chip.

Despite its value as truly persistent storage, MROM has fallen out of favor over the decades. You may be surprised to find a lot of what’s currently used in the consumer market is prone to data corruption over time spans as short as one year to one decade depending on environmental conditions.

So what are we to do if we need to have read-only data that should remain readable for the coming decades?

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Giving Micro Channel Bus Computers A Sound Blaster Bark

December 1, 2020 by Maya Posch 15 Comments

Not many people today probably remember what ‘Micro Channel Architecture’ was about, though its acronym ‘MCA’ might ring a bell. Created by IBM to replace ISA (Industry Standard Architecture) and presumably claw back some of that sweet, sweet licensing money, it didn’t quite pan out as IBM hoped. As history shows us, PCI ended up replacing MCA in all of IBM’s systems. The IBM PS/2 systems that used MCA didn’t miss out on classic 1990s cards, such as the original Sound Blaster, but today MCA versions of the Sound Blaster are admittedly rather… rare, not to mention expensive.

But, no longer: decades after the last PS/2 users have moved on, [Tube Time] proudly presents the Snark Barker MCA. It’s a fully Sound Blaster compatible sound card. It supports AdLib synthesis, digital sound playback and recording, as well as a joystick input and MIDI. Based around a Xilinx XC9572XL CPLD and featuring what looks like a full-length MCA card, it would have made an original Sound Blaster card proud.

The GitHub repository not only contains the schematics, BOM and Verilog-based HDL for the CPLD, but also extensive documentation on the assembly and programming. As a bonus, there’s a troubleshooting section which covers some of the joys that came with the sloppy implementations of MCA across systems. Definitely worth a read.

If anyone decides to build this project and use it in their IBM PS/2 system, we would love to hear about it.

Of course, if all you need is a garden variety PCI Sound Blaster clone, the original Snark Barker is the way to go.

(Thanks, Darry)

Eulogy To Arecibo: With Demise Of A Unique Scientific Facility, Who Will Carry The Torch?

November 24, 2020 by Maya Posch 50 Comments

Few telescopes will get an emotional response from the general public when it is ultimately announced that they will be decommissioned. In the case of the Arecibo Observatory in Arecibo, Puerto Rico, the past months has seen not only astronomers but also countless people across the world wait with bated breath after initial reports of damage to the radio telescope’s gigantic dish.

When the National Science Foundation announced that they would be decommissioning the telescope, there was an understandable outpouring of grief and shock. Not only is Arecibo a landmark in Puerto Rico, it is the telescope from iconic movies such as GoldenEye (1995) and Contact (1997). Its data fed public programs such as the Seti@Home and Einstein@Home projects.

Was Arecibo’s demise truly unavoidable, and what does this mean for the scientific community?

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