In this section we report on the realization of a prototipebased on a Spartan6 from Xilinx[1] and on a AM3358[2](1GHz ARM A8 processor). The communication betweenthe ARM and the FPGA elements, used for configurationand monitoring, is based on SPI. It is a synchronous serialcommunication that operates in full duplex mode with a clockfrequency selected between 1 and 10 MHz. The platformprovides several GPIO pins toimplement the interrupt serviceroutines by using a polling algorithm and some ADC devicesto sample analog signals.The system configuration and monitoring are controlled byan embedded processor: its main components (RAM block,Ethernet and I/O peripherals) are depicted in the Fig. 2. Theuse of an embedded processor has the advantage of beingflexible by means of the device tree configuration. In fact theoperating system parses the data structure at the boot timeand confugures the kernel and which device drives to load.The main elements between busses and peripheral are I2C,SPI, ADC and GIPO.A test bench has been assembled as in Fig. 3; two boardsare shown: the laser control under test and another FPGAboard used for measurements. In fact, it distributes the triggersignal to the laser control and measures the time for each laserpulse. The system configuration and all the operation modesare managed by a remote PC connected via an Ethernet link
or locally over an USB connection.Several measurements at fixed frequency mode have beendone.Of a great interest is the mode that generates hit patternsrandomically used for test and debug of DAQ and electronics.As an example, Fig. 4 shows the measured hit distributionintegrated for a double Guassian signal with two hits for eachsequence