利用状态机设计一个序列检测器，用以检测“1101”。用btn[1]和btn[0]作为输入分别代表1和0，输入的当前数字显示在数码管最后一位，每当新输入一个数字，之前输入的数字左移一位，依次显示出最近输入的四位数字，无输入时数码管不显示任何数字。clk时钟需要分频后才可作为检测时钟（建议分频至190Hz），每当检测到序列中有“1101”出现时，led[0]点亮，即数码显示管上显示“1101”时led[0]点亮；当按下btn[2]时恢复初始状态。-The use of a state machine sequence detector for detecting " 1101."　With btn [1] and btn [0] as input representing 1 and 0, the current digital input digital tube display in the last one, whenever entering a new number, enter the number before the left one, in turn shows recently four digital inputs, when no input digital tube does not show any numbers. After clk clock divider is available as a detector needs a clock (recommended crossover to 190Hz), whenever the detected sequence of " 1101"　appears, led [0] is lit, the digital display shows " 1101"　when the pipe led [0] lights　btn restore the initial state when you press [2].