A High-Speed Logic Gate Board for the Easy-Phi Project

A (long) while ago I presented you the Easy-phi project, which aims at building a simple, cheap but intelligent rack-based open hardware/software platform for hobbyists. With this project, you simply have a rack to which you add cards (like the one shown above) that perform the functions you want.

During these last months my team has been finishing the design and production of several different boards so I’ll start showing them off during these next weeks. Today I present you the High Speed Logic Gate Board, a quantum-physicist requested easy-phi module that can perform logic AND/OR functions at <2GHz speeds. This quite technical write-up is mainly about the constraints that high-speed signals pose for schematics design but is also about the techniques that are used for HS signals termination and monitoring. I hope, however, it’ll give our readers a nice overview of what the insides of a high-speed system may look like. All the files used for this board may be found on the official GitHub repository.

A Simple (and Dirty) Bill of Materials and Stock Management Utility

As many readers may already know, when I’m not featuring your projects or working on the mooltipass I try to make simple things that may be useful to electronics enthusiasts. My latest creation is a simple bill of materials generation tool, which can also do simple stock management. Unfortunately for Linux users, this utility is made using Visual Basic functions in an Excel file.

It works fairly simply: just enter your schematics’ components references in the excel sheet, along with the corresponding Digikey webpage address. Click on the “fetch” button and the script will automatically get all your component characteristics from the internet and tell you the component costs depending on the number of prototypes you want to make. Then click the “sort BoM” button and your BoM will automatically be sorted by component type and value. Another functionality allows you to check that all the components present in your BoM are also present on the (very simple) Kicad generated one. Finally, using another Excel sheet containing your current stock, the Bill of Materials will let you know if you have enough components for the assembly stage. A video of the tool in action is embedded after the break, and you can download the BoM template here (.XLSM file) and the corresponding stock file there (.XLSM file).

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A Low Cost Dual Discriminator Module for the Easy-phi Project

A few months ago I presented you the Easy-phi project, which aims at building a simple, cheap but intelligent rack-based open hardware/software platform for hobbyists. With easy-phi, you simply have a rack to which you add cards (like the one shown above) that perform the functions you want.

Recently my team finished testing our FPGA-based discriminator or “universal input” if you prefer. As easy-phi cards use a well-defined electrical signal to communicate with each other, we needed to make a card that would translate the different kinds of electrical signals from the outside, as well as perform plenty of other functions. It was therefore designed to have a 100MHz input bandwidth with an AC/DC coupled 50 ohm/high impedance input stage (x2) and 4 easy-phi outputs. For this module, we picked the (old) spartan3-an FPGA to perform the different logic functions that may be needed by the final users (high speed counter, OR/XOR/AND, pulse creation,…). Using the cortex-m3 microcontroller present on the board, it may be easily reconfigured at will. All design resources may be found on our Github, and you can always have a look at our official website.

A cortex M4 based platform with ETH, USB, BT and many on-board peripherals

Here is a very time consuming project that I worked on during last summer: an ARM Cortex M4 based platform with plenty of communication interfaces and on-board peripherals. The particular project for which this board has been developed is not really HaD material (one of my father’s funny ideas) so I’ll only describe the platform itself. The microcontroller used in the project is the ATSAM4E16C from Atmel, which has 1Mbyte of flash and 128Kbytes of SRAM. It integrates an Ethernet MAC, a USB 2.0 Full-speed controller, a sophisticated Analog to Digital Converter and a Digital to Analog Converter (among others).

Here is a list of the different components present on the board so you can get a better idea of what the platform can do: a microphone with its amplifier, a capacitive touch sensor, two unipolar stepper motors controllers, two mosfets, a microSD card connector, a Bluetooth to serial bridge, a linear motor controller and finally a battery retainer for backup power. You can have a look at a simple demonstration video I made, embedded after the break. The firmware was made in C and uses the Atmel Software Framework. The project is obviously open hardware (Kicad) and open software.

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Making the electronics for a Doppler motion sensor

There are many different sensors that can be used to detect motion in a given environment. Passive InfraRed (PIR) sensors are the most used today, as they work by detecting moving heat signatures. However, they are less reliable in the hotter days and obviously only work for animals and humans.

Sensors like the one shown in the above picture started to appear on the internet, they use the doppler effect to detect motion. I (limpkin) designed the electronics you need to add in order to get them to work.

Here is a simple explanation of the doppler effect: if you send an RF signal at a given frequency to a moving target, the reflected signal’s frequency will be shifted. It is commonly heard when a vehicle sounding a siren or horn approaches, passes, and recedes from an observer. The received frequency is higher (compared to the emitted frequency) during the approach, it is identical at the instant of passing by, and it is lower during the recession. [Read more...]

[Limpkin's] new business card

[Limpkin] decided to give the whole embedded business card thing a try. Here is his finished project, a low-profile mass storage business card that doesn’t cost an arm and a leg. Sure, the $6 price tag could score him a hundred paper cards, but those don’t light up like this one does!

The main components on the card include an AVR microcontroller, a flash memory chip, and an ESD protection chip. The latter is to make sure a static shock on the USB connector doesn’t zap the MCU. Speaking of, he went with an AT90USB162 which runs from an external 8 Mhz oscillator. Sure, it’s not the fastest thing out there, but since there’s only 16 Mb of flash on this card we don’t think you’ll notice any data transfer delay. The processor is running the LUFA stack and has two flavors of firmware. One that enumerates as an HID keyboard to automatically use keyboard shortcuts to launch a browser and load up his website. The other implements a mass storage device.

If you don’t like the electronic route, you could always go with some laser cut metal. We’ve heard that [Kevin Mitnick's] business card has snap-out lock picking tools kind of like these.