VFD Display Controller Based On CPLD

ALTERA’s EPM2210CPLD (complex programmable logic device) chip which isa small scale CPLD device is applied to design the VFD (vacuum fluorescent display)controller in this thesis; VFD module which is available for various digital, charactersand Chinese characters display is applied in VFD manufactured by the TianMa Co.,LTD.The function of VFD controller is to receive the data according to the request andsend it to the VFD for display. Its tasks mainly include work page display, setting pageswitching, power consumption page setting and clearing, alarm page processing andchecking and lower machine hooking and cancellation. The thesis firstly analyzed theoverall system, and then segments the module. Each sub-module needs not onlyfunction independence but also moderate size. The system is divided into global resetmodule, global clock generating module, rotary encoder reading and output module,rotary encoder intermediate processing module, display page control module, dataprocessing module for display, binary to hex transformation module, binary to BCDcode conversion module, FLASH address generating module, FLASH generatingmodule, FLASH data output module, serial port to the VFD module, alarm processingmodule, RS485(differential half duplex asynchronous communication standard)communication module, CPLD to CPLD and board to board communication module,etc. The logic resource of EPM2210is limited, which holds2,210logic elements. Inorder to save the logic elements, the thesis uses a variety of simple algorithms andsub-module reuse method to simplify logic. The methods used in the thesis mainlyinclude state encoding of the state machine, clock share of modules, reuse of the shiftregisters in CRC verification, reducing the address jumping times, etc.The thesis completes the VFD controller design with EPM2210CPLD chip,consuming a total of1200logic elements. This design has been integrated into thepower high voltage and high power supply control system of Zhuhai ShengPu PowerCo., LTD.