BESIII luminosity readout design based on embedded system

Zero-Degree Detector (ZDD) is a new Detector of Beijing Electron Spectrometer III (BESIII) for both double gamma event detection and luminosity monitoring to substitute the old luminosity monitor. A new luminosity readout is described in this paper which is designed in double width AMC/MTCA form factor with a large Xilinx Virtex5 FPGA in addition to normal electronic signal formation. A FPGA embedded PowerPC is used for data reading, accumulation and data transmission over a gigabit Ethernet. The setting of parameters like the discriminator threshold in Front End electronics is done via a special serial link under control of firmware in the same FPGA. This readout system has been put in operation since fall of 2012.