Memory Box Shows Photos Based On Fingerprint

With his young son’s birthday coming up in a few weeks, [Mike Buss] wanted to build him something fun that the boy could hold on to all his life. After doing some sketching, [Mike] arrived at the idea to make a memory box uses a fingerprint scanner to show different pictures based on the fingerprint.

[Mike] started by rendering the box in Blender and then cutting a sizable hole in the lid for the E-ink screen. That’s around the time the first problem came up — there were weird vertical lines in the display. Sure enough, that screen was broken. Then he added the SD card reader, but the SD card wouldn’t work, and was heating up besides. Finally, the fingerprint scanner was causing issues, but it turned out that the power supply was at fault.

After all of that, [Mike] switched from an ESP32 to a Raspi Zero W to simplify the whole process of finding a photo tagged with the person’s fingerprint. [Mike] added a Python script that listens for new memories over Wi-Fi. A memory in this case consists of a picture, a description, a list of people tagged in the picture, and some additional metadata.

One important lesson [Mike] learned was that of balancing planning vs. just taking action. If he had taken the time to consider the complexity of the tagged-photo retrieval system, he would have arrived at an SBC solution much sooner. Be sure to check out the build video after the break.

You can have all sorts of fun with fingerprint scanners, like this one that opens a secret bookcase door.

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Will There Be Any Pi Left For Us?

Our world has been abuzz with the news that Raspberry Pi are to float on the London Stock Exchange. It seems an obvious move for a successful and ambitious company, and as they seem to be in transition from a maker of small computers into a maker of chips which happen to also go on their small computers, they will no doubt be using the float to generate the required investment to complete that process.

New Silicon Needs Lots Of Cash

An RP1 chip on a Raspberry Pi 5.
The most important product Raspberry Pi have ever made.

When a tech startup with immense goodwill grows in this way, there’s always a worry that it could mark the start of the decline. You might for instance be concerned that a floated Raspberry Pi could bring in financial whiz-kids who let the hobbyist products wither on the vine as they license the brand here and there and perform all sorts of financial trickery in search of shareholder value and not much else. Fortunately we don’t think that this will be the case, and Eben Upton has gone to great lengths to reassure the world that his diminutive computers are safe. That is however not to say that there might be pitfalls ahead from a hobbyist Pi customer perspective, so it’s worth examining what this could mean.

As we remarked last year, the move into silicon is probably the most important part of the Pi strategy for the 2020s. The RP2040 microcontroller was the right chip with the right inventory to do well from the pandemic shortages, and on the SBCs the RP1 all-in-one peripheral gives them independence from a CPU house such as Broadcom. It’s not a difficult prediction that they will proceed further into silicon, and it wouldn’t surprise us to see a future RP chip containing a fully-fledged SoC and GPU. Compared to their many competitors who rely on phone and tablet SoCs, this would give the Pi boards a crucial edge in terms of supply chain, and control over the software.

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Simon Says With An RP2040

The team of [Michael] and [Chimdi] from Cornell’s Designing with Microcontrollers (ECE 4760) Fall 2023 session designed a version of Simon Says on an RP2040 which they call Pico Says. It uses UDP packets over WiFi to communicate between the players, and supports VGA graphics for output. Each player’s hardware consists of a Pico W module plus a control panel containing the four LEDs and buttons ( red, green, yellow, and blue ) plus send and reset buttons.

For purposes of this lab, the modules were build on a solderless breadboard and used perfboard for the control panels. They weren’t entirely happy with their choice of UDP because they experienced frequent datagram dropouts in the noisy environment of the microcontroller lab. They also planned to implement sound effects, but ran out of time after spending too much time on the WiFi implementation, and had to drop that feature. In the end, however, they wrapped up their project and demonstrated a working game. We can only speculate whether this bonus lesson in resource management was intended by [Dr. Hunter Adams] or not.

Two ECE 4760 course references are highlighted in the write-up that helped them jump-start the project: the UDP and VGA examples for the Pico. These are good links to put in your RP2020 toolbox for future projects, in addition to the ECE 4760 course home page itself. We’ve covered several of these projects recently, as well as the curriculum switch from the Microchip PIC32MX-based Microstick II to the RP2040 last Spring.

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The Pi Pico replacement board in question, assembled, held diagonally in some type of holder

ProPico For Your Pro Pico Needs

Ever feel like the Pi Pico board could be doing way more given its footprint? Does it bother you that the RP2040’s ADC quality is even further decreased because of the noisy onboard switching regulator? Miffed about decisions like the MicroUSB socket, the 2MB flash, or lack of the reset button? [Dmytro] brings us an open-source Pi Pico design, sporting the same RP2040 and a fully compatible footprint, but adding a number of improvements to its surroundings.

There’s a good few additions, all of them hacker-friendly – [Dmytro] adds comfortably-spaced reset and boot buttons, a USB-C socket, a dedicated low-noise voltage reference for the ADC, one more LED, and an I2C EEPROM footprint socket that is compatible with FRAM chips. Everything worth preserving is preserved – the pinout stays the same, including the SWD connector, which now sports an extra RESET pin. The bottom side USB testpoints remain, with only the four testpoints changed for more useful signals. Last but not least, the switching regulator is replaced by the venerable 1117 – you lose the ability to power your Pico from two AAs, and the capacitor series resistor requirement isn’t great, but you can easily put one of the drop-in 1117 replacement regulators on there.

What’s great is that the design is fully open-source, with KiCad files available. Want to design your own Pi Pico footprint board, improve upon this one even further, or maybe make a more tailored one? Treat yourself to the GitHub repository! There’s also a pinout diagram and a KiCanvas schematic for all your tinkering needs. We’ve covered drop-in replacements for classic drawer-inhabiting parts like the Pi Zero, for the 7805 (twice!), the 6502 CPU, and even for the DE9 serial port connector. No matter the purpose, they’re always a joy to see.

Gyro-Controlled Labyrinth Game Outputs To VGA

This gesture-controlled labyrinth game using two Raspberry Pi Pico units does a great job of demonstrating how it can sometimes take a lot of work to make something look simple.

To play, one tilts an MPU6050 inertial measurement unit (IMU) attached to one Pico to guide a square through a 2D maze, with the player working through multiple levels of difficulty. A second Pico takes care of displaying the game state on a VGA monitor, and together they work wirelessly to deliver a coherent experience with the right “feel”. This includes low latency, simulating friction appropriately, and more.

Taking a stream of raw sensor readings and turning them into control instructions over UDP in a way that feels intuitive while at the same time generating a VGA display signal has a lot of moving parts, software-wise. The project write-up has a considerable amount of detail on the architecture of the system, and the source code is available on GitHub for those who want a closer look.

We’ve seen gesture controls interfaced to physical marble mazes before, but two Raspberry Pi Picos doing it wirelessly with a VGA monitor for feedback is pretty neat. Watch it in action in the video, embedded just under the page break.

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Air Hockey Table Embraces DOOM, Retro Gaming

[Chris Downing] recently finished up a major project that spanned some two years and used nearly every skill he possessed. The result? A smart air hockey table with retro-gaming roots. Does it play DOOM? It sure (kind of) does!

Two of the most striking features are the score board (with LCD screen and sound) and the play surface which is densely-populated with RGB LED lighting and capable of some pretty neat tricks. Together, they combine to deliver a few different modes of play, including a DOOM mode.

The first play mode is straight air hockey with automated score tracking and the usual horns and buzzers celebrating goals. The LED array within the table lights up to create the appearance and patterns of a typical hockey rink.

DOOM hockey mode casts one player as Demons and the other as the Doom Slayer, and the LED array comes to life to create a play surface of flickering flames. Screams indicate goals (either Demon screams or Slayer screams, depending on who scores!)

In retrogaming emulation mode, the tabletop mirrors the screen.

Since the whole thing is driven by a Raspberry Pi, the table is given a bit of gaming flexibility with Emulation Mode. This mode allows playing emulated retro games on the scoreboard screen, and as a super neat feature, the screen display is mirrored on the tabletop’s LED array. [Chris] asserts that the effect is imperfect, but to us it looks at least as legible as DOOM on 7-segment displays.

This project is a great example of how complex things can get when one combines so many different types of materials and fabrication methods into a single whole. The blog post has a lot of great photos and details, but check out the video (embedded below) for a demonstration of everything in action. Continue reading “Air Hockey Table Embraces DOOM, Retro Gaming”

A microwave imaging setup. On the left is a monitor displaying a monochrome GUI. In the center is the RP2040-based positioning and measurement system, and on the right is a vector network analyzer.

Precise Positioning With The RP2040

Microwave imaging is similar to CT imaging, but instead of X-rays, the microwaves are used to probe the structure and composition of an object. To facilitate experimentation with microwave imaging, [Zehao Li] and [Kapil Gangwar] developed a system based on the RP2040 to control the height and rotation of a test object.

Their control system has a refreshingly physical user interface—a keypad. The keypad is used to configure the object’s position and the scanning step size, while user menus and the sample position are displayed in a clean and uncluttered interface over VGA. The RP2040 runs a multi-threaded program to handle user input, VGA display, and precise driving of two stepper motors for sample positioning.

The microwave imaging was performed by measuring the RF transmission over 2.5-8 GHz between two Vivaldi antennas on either side of the sample at a variety of angles. 2D cross-sections of the test object were reconstructed in Matlab using filtered back-projection. In this proof-of-concept demonstration, a commercial vector network analyzer was used to collect the data, but one could imagine migrating to a software defined radio (SDR) in the future.

A video demonstrating the system is embedded below the break. If you’re interested in DIY radio imaging, you might be interested in this guide to building your own synthetic aperture radar setup, or this analysis of an automotive radar chip.

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