Motion counter and trigger module

The motion counter and trigger module is a module which must be able to determine coordinates of a mobile unit according to moving sensors, and to send a serial stream when the mobile unit has reached a determined distance. More precisely, a trigger is generated when the distance has been reached, and consequently a stream is built up and sent through a serial line. Basically, the stream contains calculated coordinates values. This module must be implemented on a hardware-platform composed basically of a FPGA (Field Programmable Gate Arrays) and a processor. The processor is responsible for fetching the correct instruction for the FPGA processes execution. The moving sensors are incremental encoder wheels, which signals have to be analysed by the FPGA. However, sensors lines mustn 't be directly connected to the hardware-platform connector which is directly linked to the FPGA pins, because there is no voltage security and the FPGA can be destroyed. Therefore a voltage interface has to be developped in order to protect inputs and outputs of the FPGA pins with external elements. Then a VHDL program has to be implemented into the FPGA in order to carry out the motion counter and trigger module. A motion counter module generates the coordinates values, and it has two operation modes: The first one is to calculate coordinates according to moving sensors information, and the second one is to generate emulated coordinates. A trigger module generates a trigger each time a determined distance has been reached, and then a stream can be built up and sent through a serial line. Moreover, a receiver module gets back the serial stream, and stores the deserialized stream data into SRAM. (In this way, a control of sent stream data can be done). A practical case where this motion counter and trigger module is required is a moving unit which need to perform a measurement every ten centimeters. A trigger is generated each time the moving unit has reached ten centimeters, then a stream is sent, and the reception of this stream by an other module initiates a new trigger where measurements can be performed, and data of this measurement could be stored with the corresponding coordinates