We were looking for an inexpensive way to connect Larry Doolitte's
Low-Level RF board to EPICS. The LLRF board uses USB to connect to
the outside world so the IOC controlling it needs to be fairly
close. We purchased a SheevaPlug (http://www.globalscaletechnologies.com/p-22-sheevaplug-dev-kit-us.aspx
). for around $100 (US). The SheevaPlug is a plug computer (http://www.openplug.org/
) about the size and shape of a typical AC adapter. It has a USB
2.0 interface and 10/100/1000 ethernet and comes with Linux
installed on the flash memory. The development kit also contains a
CD with all the cross-development tools
I made a couple of changes to <base>/configure/os/
CONFIG.Common.linux-arm on my Linux host machine and, to my
considerable surprise, was able to build EPICS base R3.14.11, snc/
seq and asyn with no other changes. I also built the GNU
Universal Software Radio Project libraries which are needed to
communicate with the LLRF card. I used apt-get on the SheevaPlug to
install the nfs-common and screen packages.
I am now running the IOC on the SheevaPlug and controlling/
displaying the EPICS process variables using MEDM on my OS X
machine. With a 2.3 MB/s flow from the LLRF card and processing/
displaying the twelve 1024-sample waveform records 5 times per
second (242 kiB/s to the EPICS client) the CPU load on the
SheevaPlug is 4 to 5%.
So, if you're looking for a really inexpensive way to interface USB
equipment to EPICS you might find this a reasonable way to go.
--
Eric Norum
[email protected]