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.

Easy-phi: an Open Source Platform for Experimenters

As a few of Hackaday readers may already know, my day job involves working with high speed electronics. For the last few months, my team at [Université de Genève] in Switzerland has been working on an open source platform (mostly) targeted for experimenters: the easy-phi project. The main idea is to build a simple, cheap but intelligent open hardware/software platform consisting of a 19″ frame (or smaller), which can house a big variety of electronic modules. Hobbyist would therefore only make/buy the modules that would suit their needs and control them through a web page / standalone application / Labview module.

I detailed in more depth on my website the technical aspects of the project. To give you a quick and simple overview, the rack is essentially a USB hub that connects all the modules to a Cubieboard. It also integrates a few synchronization signals, a clock and a monitoring system for voltages, temperatures, power consumption. The modules are made of template + module specific electronics. The template electronics are part of the ‘easy-phi standard’, they consist of the Arduino compatible SAM3X8E microcontroller and of a few other power related components. This ensures electrical and firmware compatibility between the rack and modules that you guys may develop. It is important to note that the modules are enumerated on the USB bus as composite CDC (communication device) and MSC (mass storage). The CDC is used to configure the module while the MSC allows you to grab its documentation, resources, and standalone application in case you use the module without the rack.

The chosen schematics / layout software is Kicad, and all current files can be found on our github. Others will be uploaded once we have tested the other modules currently in the pipe. As the ones we’re developing are physics oriented, we hope that enthusiasts will bring easy-phi to other domains. Don’t hesitate to contact us if you have any question or if you’d like to contribute.