I've been playing with embedded system boards to use in a couple of astro related projects. Read about Raspi clusters (Brambles) and decided to build one to experiment with. The idea is to use them to control the focus dew heaters and such at first with a touchscreen handpad I came up with. To do the focus calculations quickly was a bit beyond the capabilities of a single board or even a few of them in a parallel mode for what I wanted to do with it but using the GPU on each board is a whole new avenue. They are just starting to be documented and api's built for them but one of the first implementations is an FFT which is what I want to use for my focus calculations. Basically spits out a couple of points that get wider or closer depending on how sharp the image is. The Pi's have Mathematica on them and it has some parallel capabilities. I posted up to their forum and one of the members showed me how to use the FFT method to determine focus. Having supported large clusters in the past I thought I'd give it a go. Spent the last couple of weeks putting it together. Its passed all the test suite and I'm working towards getting the GPGPU FFT code working on it now. Mathematica also does a stellar job of selecting all the stars in an image you feed it and splitting out all the stars into nice bite size morsels for the compute engine to munch on. The cluster software is a variant of the Beowolf cluster software that most of the bit research projects run on like Cern. Its MpiCh and comes from Argonne National labs. It comes with Hydra which is a manager. Hydra runs on another board a pcduino which is the executive for the cluster. It has SATA so it supplies the shared disk for the nodes. Since this is going to do all the work on the imaging rig it needed a place to store images and for scratch space for the nodes to build up tables and such. The nodes are all connected via a switch for the message passing protocol. The pcduino functions as a gateway to the outside world for the nodes. It has Wifi and ethernet so I use the ethernet connection into the switch to communicate with the nodes and Wifi to the outside world. This will be the connection to the scope from inside the house. The pcduino runs X11VNC so its capable of putting up a full graphic display to my pc in the house over the wifi link. The idea is to have each node use a core for housekeeping a core for its main task and the other two cores go into a pool for calculations etc. There is also another Pi for a hot spare. If one of the nodes has a problem its ip address and machine state will be transfered to this node and the switch over accomplished via a couple of relays to turn off the bad one and turn on the good one which will start up right where the other one left off. Overkill I know but its fun to set up and I wanted my micro cluster to be just like the big boys I used to work on. I'm recompiling the astro distro for linux to use for the software image. Xephem is already done and the rest are close. the linux on these boards is a cut down version so lots of libs and such you have to go looking for to port these apps. Going with Indi drivers. One of the main goals is to have source for everything. Then you don't need any stinkin tech support Too hot to do any imaging. I tried the other night and my camera was bumping up to 100deg before I had it focused. Too expensive to torture like that so I'm going full tilt on this trying to have it ready for fall.

Griz