Displaying Characters on an LCD Character Module - Hantronix, Inc

More documents

Recommendations

Info

Application NoteINC.Crystal Clear and Visibly Superior LCD ModulesIII. Software Flowchart:BeginWriteP1 = 38h, Command_ByteData=[DPTR]4.1mSec DelayP1 = 38h, Command_Byte100uSec DelayInitialization?Data = 99hNoCall Data_ByteYesReturnP1 = 38h, Command_ByteP1 = 0ch, Command_ByteP1 = 01h, Command_ByteINC DPTRCGRAMFirst_LineSecond_Line:Command_byteData_byteIDLERS lowRS high*CGRAM: Program in CGRAM DATAFirst_Line: Display First LineSecond_Line: Display Second LineRW low - Enable writeDELAYE low - generate enable pulseStart TimerTestFlag = 0Timer0 Interrupt:TestFlag=1Stop TimernopTestFlag=1?NoYesReturnE high - pull up enable signalRW high - Read modeConfigure P1 to input portDB7 = 1?YesNoReturn- Page 2 -
Application NoteINC.Crystal Clear and Visibly Superior LCD Modules;**********************************************************;; Application Note:; =================; <strong>Displaying</strong> <strong>Characters</strong> on an LCD Character Module;; Description: Demo software to display “canned”message and custom characters..; Controller: Phillips 87C751; LCD controller: HD44780, KS0066, SED1278;;*************************************************************; Constant Definition;*************************************************************EnableT0 equ 082h ;enable timer0Disable equ 000h ;disable timerD4100h equ 00ch ;timer reload high byte def.D4100l equ 003h ;timer reload = 4.1mSec.D100h equ 000h ;timer reloadD100l equ 04ch ;timer reload = 100uSec.;*****************************************; Ram Definition;*****************************************Flags DATA 020h ;flagTstFlag BIT Flags.0 ;interrupt flag bit;*****************************************; Port Connections; =================; P1.0 -> D0; P1.1 -> D1; P1.2 -> D2; . . .; P1.7 -> D7; P3.0 -> Enable; P3.1 -> RS; P3.2 -> RW;*******************************************************; Interrupt Vectors; ------------------org 000hjmp PowerUp ; Power up reset vectororg 003hjmp ExInt0 ; External interrupt 0 vectororg 00bhjmp Timer0 ; Counter/ Timer 0 int vectororg 013hjmp ExInt1 ; External int 1 vectororg 01bh ;jmp Timer1 ; Timer 1 int vectororg 023hjmp I2C ; I2C serial int vectororg 50hPowerUp:;***** Timer 0 Interrrupt preparationclr TR ;disable timerclr TF ;clear overflow;**************************************; LCD Initialization Routine;**************************************cinit: clr P3.1 ;RS lowclr P3.2 ;RW lowsetb P3.0 ;Enablemov RTL,#D4100l ;set timer reload valuemov RTH,#D4100h ;dealy time = 4.1mSecsdone:mov p1,#38hacall command_byteacall ddelay ;initial delay 4.1mSecmov RTL,#D100l ;set timer reload valuemov RTH,#D100h ;dealy time = 100uSecmov p1,#38h ;function setacall command_byteacall ddelay ;busy flag not avail. yetmov p1,#38h ;function setacall command_bytemov p1,#0ch ;display onacall command_bytemov p1,#01h ;clear displayacall command_byteacall cgram ;define custom fontsacall first_line ;display first lineacall second_line ;display second linesetb IDLE ;power down modejmp sdone;********************************************************;Subroutine: WRITE;=================;Purpose: To feed in data/command bytes to the LCD module;Parameters:dptr = should be set to the beginning of; the data byte address; Data bytes should be finished with 99H;Alg: get a new data/command byte; while (new data != 99h) {; set port1 with new data; call data_byte; increment data pointer; }; return;********************************************************write:write_loop:mov a,#0movc a,@a+dptrcjne a,#99h,write_contretwrite_cont:mov p1,aacall data_byteinc dptrjmp write_loop;************************************************; Delay Routine:; Delay periond = 4/3uSec * DefRth,l;************************************************ddelay:setb TR ;start timermov IE,#EnableT0 ;enable timerclr TstFlag ;reset flagdloop: jnb TstFlag,dloopret;********************************; set address to beginning; of CG RAM;********************************- Page 3 -
Page 1: Application NoteINC.Crystal Clear a

Displaying Characters on an LCD Character Module - Hantronix, Inc

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?