Embedded controllers for local board-control

The LHCb experiment at CERN has a large number of custom electronics boards performing high-speed data-processing. As in any large experiment the control and monitoring of these crate-mounted boards must be integrated into the overall control-system. Traditionally this has been done by using buses on the back-plane of the crates, such as VME. LHCb has chosen to equip every board with an embedded micro-controller and connecting them in a large Local Area Network. The intelligence of these devices allows complex (soft) real-time control and monitoring, required for modern field programmable gate array (FPGA) driven electronics. Moreover, each board has its own, isolated control access path, which increases the robustness of the entire system. The system is now in pre-production at several sites and will go into full production during next year. The hardware and software will be discussed and experience from the R&D and pre-production will be reviewed, with an emphasis on the advantages and difficulties of this approach to board-control.