A Sound and LED-tastic Tricycle Shopping Cart

What do you get when you take a massive number of LEDs and combine them with a shopping cart and a bicycle? An awesome rave-mobile created by [kramerr]. He’s even taking it one step further by making the electronics solar powered.

[Kramerr] controls the LEDs with multiple WS2803 LED drivers. Three PIC18F4550s control the WS2803s over SPI. He devised a neat way of exciting the LEDs from music by using a pair of graphic equalizer display filter chips, MSGEQ7s, to drive the PICs to create patterns. A USB input also allows the PICs to display song titles or other information.

leds and boards

The mechanical design is as impressive as the electronics. The rear half of a bicycle is welded to the frame of the shopping cart with the cart’s handle used for steering. The shopping cart’s rear wheels are replaced by small bicycle wheels.

But [Kramerr] wasn’t done. He built his own solar panel since he couldn’t find one to fit the size requirements. The panel consists of 26 cells connected in series to provide 1A at 13V on a sunny day. A solar charge controller keeps a standard 12v lead acid battery ready to power the tricycle cart.

And there is still more! There is a sound system driven by a Raspberry Pi. The Pi also drives the USB inputs when [Krameer] wants to display song titles or artists instead of the audio patterns.

There are at least four hacks in this project each worthy of applause. [Karmeer] deserves an ovation for doing all of them in one project. If you are looking for less bling and less pedaling may we direct you to this powered, riding shopping cart.

Some rave music and lights via video after the break.

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Light Up Your Day With This LED Clock

We love clocks, and [Chris] got our attention with the internet enabled Light Clock. Time is displayed via RGB LED strip in a number of different ways around a 3D printed white disk. All the modes are based on two selectable colors to indicate hours and minutes, either in a gradient fashion or a hard stop.

Light is provided by a 144 LED neopixel strip and is powered by a beefy 4 amp 5 volt power supply, which also powers the controller. Brains are provided by a ESP8266 powered NodeMCU-12E board, and software is written using ESP8266 for Arduino core.

Being a WiFi enabled micro controller it is a simple matter of connecting to the clock using WiFi and using the embedded web pages to select your local timezone, color palette, and display mode. The correct time is set by network and will never be wrong. While there is a Kickstarter for selling the finished project, instructions and software are provided for making your own if you wish.

Join us after the break for the promotional Kickstarter and demonstration video

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Experiences In Developing An Electronics Kit

This year’s Hackaday Prize included a category for the Best Product, and there is perhaps no project that has inspired more people to throw money at their computer screens than [Oscar Vermeulen]’s PiDP-8/I. It’s a replica of the PDP-8/I from 1968. Instead of discrete electronics driving the blinkenlights and switches on the front of this computer, [Oscar]’s version uses a Raspberry Pi and the incredible SIMH emulator for dozens of old mainframes and minicomputers. It is, for all intents and purposes, a miniaturized version of a 50 year old computer that will fit on your desk and is powered by a phone charger.

Check out the video of [Oscar]’s talk below then join us after the break for more discussion of his work.

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Swapping GPIO Pins on the Pi Zero for Audio

The new Raspberry Pi Zero is generating a lot of discussion, especially along the lines of “why didn’t they include…?” One specific complaint has been that audio is only available through the HDMI port. That’s not entirely true as pointed out by Lady Ada over at Adafruit.

Something to remember about the entire Pi family is the pins on the Broadcom processors are multipurpose. Does it increase the confusion or the capabilities? Take your pick. But the key benefit is that different pins can handle the same purpose. For audio the Greater Than Zero Pis (GTZPi) use PWM0_OUT and PWM1_OUT on the processor’s GPIO pins 40 and 45. On the GRZPis these feed a diode, resistor and capacitor network that ends at the audio output jack. They don’t appear on the GPIO connector so cannot be used on the Zero.

The multi-pin, multi-purpose capability of the Broadcom processor allows you to switch PWM0_OUT to GPIO 18 and PWM1_OUT to GPIO 13 or 19. Add the network from the Adafruit note, or check this schematic from the Raspberry Pi site – look at the lower right on the second page.


While you’re checking out the audio hack at Adafruit, read through the entirety of Introducing the Raspberry Pi Zero. Lady Ada provides a great description of the Zero and what is needed to start using it.

If you’re looking for Zero hacking ideas you might check the comments in our announcement about the Zero or article on the first hack we received. There is a lot of grist for the hacking mill in them.

KiCad Utilities Generate Parts; Track Costs

The popularity of KiCad keeps increasing, and not only are more people converting to it and using it for their projects, but there’s also a growing number of folks actively contributing to the project in the form of libraries, scripts and utilities to improve the work flow.


[Dave Vandenbout] a.k.a [xesscorp] has written a couple of utilities for KiCad. When working with large multi pin parts such as micro-controllers, creating a schematic symbol from scratch using the traditional KiCad schematic library editor can be quite tedious. KiPart is a python script that uses a CSV table as its input to generate the KiCad schematic symbol and is able to create multi-part symbols too. Usage is quite simple. The csv file needs a part name on its first row. The next row contains the headers. ‘Pin’ number and Pin ‘Name’ are the minimum required. Additionally, you can add in ‘Unit’, ‘Side’, ‘Type’, and ‘Style’. Unit is used when defining multi-unit parts. Side decides the location of the pin, Type its function, and Style is its graphic representation. Running the KiPart python script then results in a nice KiCad schematic symbol. Besides, KiPart can specifically generate schematic symbols for the Xilinx 7-Series FPGAs and the Cypress PSoC5LP. There are a whole host of options to customize the final output, for example ordering pin placement based on pin number, or pin name or pin function. Source files can be obtained from the [xesscorp] Github repository.


KiCostAnother useful utility from [xesscorp] is KiCost. It is intended to be run as a script for generating part-cost spreadsheets for circuit boards developed with KiCad. The one piece of information you need to add to your schematic parts is a manufacturers part number. The KiCost Python script then processes the BOM XML file, reading the manufacturer part number, scraping the web sites of several popular distributors for price and inventory data, and creating a costing spreadsheet. You can grab the source files from the KiCost Github repository.

Check the two videos below where [Dave] walks through the two utilities.

Thanks to [RoGeorge] for sending in this tip by commenting on the Open Source FPGA Pi Hat built by [Dave] that we featured recently.

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Hacklet 87 – Roomba Projects

First introduced in 2002, The iRobot Roomba was conceived as a robotic vacuum cleaner. Just about every hacker, maker, and engineer out there immediately wanted one. The Roomba proved to be more than just a vacuum though; it was the perfect base for any household robotics project. Before long Roombas were being hacked to do way more than sweep your floor. iRobot recognized this, and added a hacker friendly serial port to later model Roombas. They even released a vacuumless version called the iRobot Create. Thousands of projects have literally ridden on the wheels of the Roomba. This week’s Hacklet is all about Roomba projects.

roomba1We start with [fuzzie360] and Poor Man’s Raspberry Pi Turtlebot. [Fuzzie360] has their Roomba running Robot Operating System (ROS). ROS actually is running on an on-board Raspberry Pi. While Willow Garage may be out of business, ROS lives on as an open source project run by Unbounded Robotics. Installing it can be a chore though. While [Fuzzie360] hasn’t given a full tutorial, they have offered to give advice if and when you get stuck.

A Raspberry Pi would be overkill for the simple suite of sensors built into the Roomba, but it’s perfect for [fuzzie3680’s] modified setup with a Microsoft Kinect. [Fuzzie360’s] goal is to have a robot that can vacuum the hostile territory of a university apartment.


roomba2Next up is [Sircut] who upgraded his Roomba’s power cell. Early Roombas were designed to use Nickle Metal Hydride (NiMH) batteries. The individual cells are built into a proprietary iRobot battery pack. NiMH can’t hold a candle to Lithium Ion batteries though. Lithium Ion cells are very common these days in devices like cell phones and laptops. In fact, [Sircut] used 18650 sized laptop cells for this upgrade. [Sircut] also added the essential LiIon battery protection circuit to make sure those cells stay happy. A voltmeter provides a visual reference that the batteries aren’t becoming overcharged. An upgrade like this will likely double the Roomba’s runtime, but it does come at a cost. Roomba’s original charge dock can no longer be used as the on-board charge circuitry isn’t designed for LiIon battery charge algorithms.

roomba3Next is [Marcel Varallo] with Robot Wars for the Commuter. How does the IT department blow off steam? Fighting robots of course! Unfortunately, [Marcel’s] coworkers aren’t all programming mavens. Hopefully some programming is in the cards for them down the road. For now though, [Marcel] has created a robot fighting league using nearly stock Roomba robots. Each bot gets a set of 3 balloons and 3 pins. A balloon represents a life. Once your lives are all popped, you’re dead! [Marcel] also created an upgrade system where winning ‘bots can move on to stronger weapons like flamethrowers. During his research, [Marcel] found out that the brushes in his Roomba are powerful enough to sweep dust and debris up without the vacuum enabled. So he’s disabled the vacuums for longer cleaning battle times.

roomba4Finally we have [Fredrik Markström] and ESP8266 controlled Roomba. [Fredrick] is hacking an ESP8266 module to be the main computer of this little Robot. Of course, a ‘8266 means it will be carrying WiFi, so this robot needs to have a web interface. [Fredrik’s] first problem was powering the ESP8266. The Roomba’s battery runs around 15 volts, which is definitely not friendly to the 3.3 volt ESP8266. A switching DC to DC converter was in order, and [Fredrik] found the perfect candidate on eBay. The ‘8266 will control the Roomba through the serial interface included on all the current models. [Fredrik] has big plans for this ‘bot, including navigation and advanced vacuuming algorithms.

If you want to see more Roomba projects, check out our new Roomba project list! If I missed your project, don’t be shy, just drop me a message on Hackaday.io. That’s it for this week’s Hacklet. As always, see you next week. Same hack time, same hack channel, bringing you the best of Hackaday.io!

Bartop Arcade Honors Aspect with 4:3 iPad Screen

Let’s face it, we all love arcades, but not all of us can fit a full size stand-up in our homes. [Bentika] knew the solution was a bartop style cabinet, but it had to be designed and built to his specifications. You see, [bentika] is an aspect ratio nerd. Only a proper 4:3 screen would do for emulating games designed for just such a display. Modern 4:3 displays are hard to come by, unless of course you have an iPad handy. The 1024 x 768 screens used on the early model iPads are perfect for the task.

Driving these screens used to be a chore, but thanks to hacker reverse engineering and overseas manufacturing, these days, controllers are only a few clicks away. [Bentika] ordered a controller for the iPad 1 screen from eBay. What he got was a controller that only worked with the iPad 2 screen. Thankfully he had a pile of old iPads to play with, so it wasn’t an issue.

[Bentika] designed his cabinet using AutoDesk 123D based upon reddit user [joshendy’s] basic outline. His final cut patters were created with Adobe Illustrator. He was able to get the entire cabinet laser cut for around $160, including materials. Cabinet assembly was easy, thanks to plenty of square gussets used to align the various pieces.

The controller for this arcade is of course a Raspberry Pi 2 running RetroPie. [Bentika] used a control block to interface the joystick and buttons to the Pi itself. RetroPie lends itself to “keyboardless” operation, he didn’t have to bring any of the Pi’s USB ports outside the case.

We have to say the final results are very nice. This system has all the portability of a CRT based bartop setup without the weight. You can check out more discussion of this hack over on [Bentika’s] Reddit thread, or click past the break for the video.

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