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479 Articles

A Raspberry Pi Rain Man In The Making

October 13, 2017 by 11 Comments

We see a lot of Raspberry Pis used to play games, but this is something entirely different from the latest RetroPie build. This Raspberry Pi is learning how to read playing cards, with the goal of becoming the ultimate card counting blackjack player.

If [Taxi-guy] hasn’t named his project Rain Man, we humbly suggest that he does so. Because a Pi that can count into a six-deck shoe would be quite a thing, even though it would never be allowed anywhere near a casino. Hurdle number one in counting cards is reading them, and [Taxi-guy] has done a solid job of leveraging the power of OpenCV on a Pi 3 for the task. His description in the video below is very detailed, but the approach is simple: find the cards in a PiCam image of the playing field using a combination of thresholding and contouring. Then, with the cards isolated, compare the rank and suit in the upper left corner of the rotated card image to prototype images to identify the card. The Pi provides enough horsepower to quickly identify an arbitrary number of non-overlapping cards; we assume [Taxi-guy] will have to address overlapping cards and decks that use different fonts at some point.

We’re keen to see this Pi playing blackjack someday. As he’s coding that up, he may want to look at algorithmic approaches to blackjack strategies, and the real odds of beating the house.

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Emulate ICs In Python

September 26, 2017 by 16 Comments

Most people who want to simulate logic ICs will use Verilog, VHDL, or System Verilog. Not [hsoft]. He wanted to use Python, and wrote a simple Python framework for doing just that. You can find the code on GitHub, and there is an ASCII video that won’t embed here at Hackaday, but which you can view at ASCIInema.

Below the break we have an example of “constructing” a circuit in Python using ICemu:

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Arduino And Pi Breathe New Life Into Jukebox

September 22, 2017 by 6 Comments

What do you do when someone gives you a Wurlitzer 3100 jukebox from 1969, but keeps all the records? If you are like [Tijuana Rick], you grab an Arduino and a Rasberry Pi and turn it into a really awesome digital music player.

We’ll grant you, making a music player out of a Raspberry Pi isn’t all that cutting edge, but restoration and integration work is really impressive. The machine had many broken switches that had been hastily repaired, so [Rick] had to learn to create silicone molds and cast resin to create replacements. You can see and hear the end result in the video below.

[Rick] was frustrated with jukebox software he could find, until he found some Python code from [Thomas Sprinkmeier]. [Rick] used that code as a base and customized it for his needs.

There’s not much “how to” detail about the castings for the switches, but there are lots of photos and the results were great. We wondered if he considered putting fake 45s in the machine so it at least looked like it was playing vinyl.

Of course, you don’t need an old piece of hardware to make a jukebox. Or, you can compromise and build out a replica.

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Cheap And Easy Motion Tracking

September 17, 2017 by 13 Comments

[Koppany Horvarth] set out to create a dirt-cheap optical tracking rig for VR that uses only two cameras and a certain amount of math to do its thing. He knew he could do theoretically, and wouldn’t cost a lot of money, but still required a lot of work and slightly absurd amount of math.

While playing around with a webcam that he’d set up to run an object-tracking Python script and discovered that his setup tended to display a translucent object with a LED inside of it as pure, washed-out white. This gave [Koppany] the idea that he could use such a light as part of his object tracking project. He 3D-printed 50mm hollow spheres out of transparent PLA, illuminated via a LED and powered by a 5V power supply hacked from an old USB cable. After dealing with some lens flares, he sanded down the PLA a little to diffuse the light and it worked like a charm.

To learn more check out his GitHub code repository. You can also take inspiration in some of the other motion tracking posts we’ve published in the past, like motion tracking on the cheap with a PIC and this OpenCV Airsoft turret.

Remote Controlled Streaming Speakers

September 14, 2017 by 16 Comments

For want of a better use of a spare Raspberry Pi Zero W and a set of LogitechZ-680 surround sound speakers, [Andre van Kammen] hacked them together to make them stream music playing from his phone.

It was stumbling across the Pi Music Box distribution that really got the ball rolling, and the purchase of a pHAT DAC laid the foundation. Cracking open the speakers’ controller case, [Kammen] was able to get 5V of power off some terminals even when the speakers were on standby — awesome! — which the Pi could use. Power and volume are controlled via the Pi’s GPIO pins with a diode to drop the voltage and prevent shorts.

Now, how to tell whether the speakers are on or off? Well, a pin on the display connector changes to 4.3V when it’s on, so wiring a 10k resistor and a diode to said pin is a hackable solution. Finishing off the wired connections, it proved possible to cram the pHAT DAC inside the controller case with the GPIO header sticking out the back to mount the Pi upon with no other external wires — double awesome!

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Bodging On More Flash Memory

September 10, 2017 by 32 Comments

[Curmudegeoclast] found himself running out of flash memory on a Trinket M0 board, so he decided to epoxy and fly-wire a whopping 2 MB of extra flash on top of the original CPU.

We’ll just get our “kids these days” rant out of the way up front: the stock SAMD21 ARM chip has 256 kB (!) of flash to begin with, and is on a breakout board with only five GPIO pins, for a 51 kB / pin ratio! And now he’s adding 2 MB more? That’s madness. The stated reason for [Curmudegeoclast]’s exercise is MicroPython, which takes up a big chunk of flash just for the base language. We suspect that there’s also a fair amount of “wouldn’t it be neat?” in the mix as well. Whatever.

The hack is a classic. It starts off with sketchy wires soldered to pins and breadboarded up with a SOIC expander board. Following that proof of concept, some degree of structural integrity is brought to the proceedings by gluing the flash chip, dead-bug, on top of the microcontroller. We love the (0805?) SPI pullup resistor that was also point-to-point soldered into place. We would not be able to resist the temptation to entomb the whole thing in hot glue for “long-term” stability, but there are better options out there, too.

This hack takes a minimalist board, and super-sizes it, and for that, kudos. What would you stuff into 2 MB of free flash on a tiny little microcontroller? Any of you out there using MicroPython or CircuitPython care to comment on the flash memory demands? 256 kB should be enough for anyone.

DIY Wireless Sprinkler System? Don’t Mind If I Do.

September 5, 2017 by 13 Comments

What to do once you have a sprinkler system installed on your property: buy a sprinkler control system or make your own? The latter, obviously.

[danaman] was determined to hack together a cheap, IoT-enabled system but it wasn’t easy — taking the better part of a year to get working. Instead of starting right from scratch, he used the open-source Sustainable Irrigation Platform(SIP) control software — a Python sprinkler scheduler with some features [danman] was looking for(eg: it won’t activate if there’s rain in the forecast). Since he wasn’t running it with a Raspberry Pi as recommended, [danman] wrote a Python plugin that runs on his home server as a daemon which listens to TCP port 20000 for connections and then updates the relevant relays. Ok, software done; on to the relay controller box!

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