Day: March 10, 2023

That Cheap USB Charger Could Be Costly

March 10, 2023 by 31 Comments

[Big Clive] picked up a keychain battery to charge his phone and found out that it was no bargain. Due to a wiring mistake, the unit was wired backward, delivering -5 V instead of 5 V. The good news is that it gave him an excuse to tear the thing open and see what was inside. You can see the video of the teardown below.

The PCB had the correct terminals marked G and 5 V, it’s just that the red wire for the USB connector was attached to G, and the black wire was connected to 5 V. Somewhat surprisingly, the overall circuit and PCB design was pretty good. It was simply a mistake in manufacturing and, of course, shows a complete lack of quality assurance testing.

The circuit was essentially right out of the data sheet, but it was faithfully reproduced. We should probably test anything like this before plugging it into a device, but we typically don’t. Does our phone protect against reverse polarity? Don’t know, and we don’t want to find out. [Clive] also noted that the battery capacity was overstated as well, but frankly, we’ve come to expect that with cheap gadgets like this.

This isn’t, of course, the first phone charger teardown we’ve seen. This probably isn’t as deadly as the USB killer, but we still wouldn’t want to risk it.

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Hacker Hotel 2023 Had A Very Cool Badge

March 10, 2023 by 8 Comments

One effect of the global pandemic was that there were relatively few events in our sphere for a couple of years. This and that other by-product of COVID-19, the chip shortage, meant that over the past year we’ve been treated to several event badges that should have appeared in 2020 or 2021, but didn’t due to those cancelled events. We were lucky enough to receive probably the last of these delayed badges in mid February, as we made the journey to the central part of the Netherlands to Hacker Hotel 2023.

A Puzzle, A 4-Bit Computer, And An Artwork

The badge takes the form of a rectangular PCB with all parts on the top side. The brains of the operation is an RP2040, and it’s powered by a CR2032 coin cell in a holder.  It’s divided into two parts, the top third which carries the circuitry and the lower two thirds of which as a row of buttons and LEDs. It’s pretty obvious from the start that it has data and address lines of a 4-bit computer, and as well as these there is an evident serial port and a USB socket. The artwork comes form the same artist whose work graced both the previous Hacker Hotel badge and the MCH2022 badge, and the rear of the PCB makes full use of all layers to create a mystical puzzle. The sum is to create a puzzle game intended to entertain the visitor, take them round the venue, and find clues to an eventual solution. I love the design both from an artistic and technical viewpoint, but have to admit that the puzzle aspect isn’t really my thing. Thus here we’ll concentrate on the badge hardware and production, and mention the puzzles only in passing. Continue reading “Hacker Hotel 2023 Had A Very Cool Badge” →

Cornell Updates Their MCU Course For The RP2040

March 10, 2023 by 16 Comments

The School of Electrical and Computer Engineering at Cornell University has made [Bruce Land]’s lectures and materials for the Designing with Microcontrollers (ECE 4760) course available for many years. But recently [Bruce], who semi-retired in 2020, and the new lecturer [Hunter Adams] have reworked the course and labs to use the Raspberry Pi Pico. You can see the introductory lecture of the reworked class below.

Not only are the videos available online, but the class’s GitHub repository hosts extensive and well-documented examples, lecture notes, and helpful links. If you want to get started with RP2040 programming, or just want to dig deeper into a particular technique, this is a great place to start.

From what we can tell, this is the third overhaul of the class this century. Back in 2012 the course was using the ATmega1284 AVR microcontroller, and in 2015 it switched to the Microstick II using a Microchip PIC32MX. Not only were these lecture series also available free online, but each has been maintained as reference after being replaced. One common thread with all of these platforms is their low cost of entry. Assuming you already have a computer, setting up the hardware and software development environment for these modules costs less than the price of a pizza dinner, a fact no doubt appreciated by the ECE department’s budget director.

We’ve covered this course before back in 2015 when it first changed. Another free online course on embedded system design is from [Prof James Conrad] at UNC Charlotte, based on the Renasas RX63N microcontroller — the UNC Charlotte team drove development of the autonomous vehicle project we covered back in 2009. If you know of other online embedded systems classes, let us know in the comments below.

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A Tape Loop Echo You Can Build

March 10, 2023 by 18 Comments

Echo and reverb are now electronic audio effects done in a computer or an integrated circuit, but originally they were achieved through mechanical means. Reverb units used springs, and echo units used loops of magnetic tape. As a musician hankering after a mechanical tape echo unit, [Adam Paul] was left with no choice but to build his own. We featured an early prototype, but now he’s back with a finished version that’s intended to be replicated by other musicians.

The unit takes a cassette mechanism from one of the last still-manufactured players available through the usual sources. It splits record and play heads, with the normal cassette replaced with a tape loop made from extra-thick computer tape. A custom PCB replaces most of the electronics, and the auto-reverse system is disabled.

The result is a functional tape echo system, as can be seen in the video below the break. This is ready to build yourself, with everything on a GitHub repository and an extremely comprehensive build guide, so do any of you fancy a go?

Read about the device’s earlier incarnation here.

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