Spartan-3A/3AN Starter Kit Board User Guide www.xilinx.com 43UG334 (v1.0) May 28, 2007RChapter 5Character LCD ScreenOverviewThe Spartan-3A/3AN Starter Kit board prominently features a 2-line by 16-characterliquid crystal display (LCD). The FPGA controls the LCD via the eight-bit data interfaceshown in Figure 5-1. The Spartan-3A/3AN Starter Kit board also supports the four-bit datainterface to remain compatible with other Xilinx development boards.Caution! When using four-bit mode, the FPGA must drive the LCD_DB<3:0> signals High.Once mastered, the LCD is a practical way to display a variety of information usingstandard ASCII and custom characters. However, these displays are not fast. Scrolling thedisplay at half-second intervals tests the practical limit for clarity. Compared with the50 MHz clock available on the board, the display is slow. A PicoBlaze processor efficientlycontrols display timing plus the actual content of the display.Figure 5-1: Character LCD InterfaceUG334_c5_01_052407DB7DB6DB5DB4E(Y15)(AB16)(Y16)(AA12)FPGACharacter LCDDisplayLCD_DB<7>LCD_DB<6>LCD_DB<5>LCD_DB<4>RSR/W(AB4)(Y14)(W13)Four-bit datainterfaceLCD_ELCD_RSLCD_RW390Ω(AB12)(AB17)(AA13)(Y13)LCD_DB<2>LCD_DB<1>LCD_DB<0>LCD_DB<3> DB3DB2DB1DB0Eight-bit data interfaceAll
