Halny: a digital signal processor based module for the readout of silicon strip detectors

We describe a four-channel, digital-signal-processor-based readout board, equipped with analog-to-digital converters. A series of identical boards work in parallel in the Belle experiment at KEK, performing a zero-suppressing readout of the silicon vertex detector. A cluster-searching algorithm executes quickly enough to allow low deadtime readout at a 500 Hz trigger rate. DSP code downloaded to the boards can be easily modified, affording a high degree of flexibility. We describe the board hardware, the algorithms employed in the experiment, and the software used to implement them