4*4键盘显示的4x4键盘识别与显示模块。小键盘中有0~f共16个按键，小键盘和数码管都连接到PLD芯片上，要求：按下哪个按键，数码管就显示哪个数码，松手后仍然显示该数码，直到按动新的按键。显示字符字形如表5-1所示。在此设计中，7段数码管只是个验证工具，因为实际应用中通常是一排数码管，而不是一个数码管。PLD芯片在此主要完成按键识别和显示驱动。-4* 4 keyboard shown 4x4 keyboard identification and display module. Small keyboard in the 0 ~ f has a total of 16 keys, small keyboard and digital tube are connected to the PLD chip, the requirements: Press any button, digital controls, it shows what the digital, let go after the remains showed that the digital, pressed until the new button. Show the shape of characters such as shown in Table 5-1. In this design, 7 digital tube is only a validation tool, for practical applications is usually a row of digital tube, rather than a digital pipe. PLD chips in the completion of this major keys to identify and display driver.