Bas van Drunen Littel / ST7920

Simple driver for the ST7920 graphic LCD 128x64. Basic functions for displaying internal ROM fonts like a 16x4 LCD Extended function to fill the screen with a bitmap

st7920.cpp@0:1a97e0243dbc, 2012-06-29 (annotated)

Committer:
Bas
Date:
Fri Jun 29 22:47:51 2012 +0000
Revision:
0:1a97e0243dbc
Function added for displaying vertical oriented bitmaps

Who changed what in which revision?

UserRevisionLine numberNew contents of line
Bas 0:1a97e0243dbc 1 #include "st7920.h"
Bas 0:1a97e0243dbc 2
Bas 0:1a97e0243dbc 3 ST7920::ST7920 (PinName _RS,PinName _RW, PinName _E, PinName DB0, PinName DB1, PinName DB2, PinName DB3, PinName DB4, PinName DB5, PinName DB6, PinName DB7)
Bas 0:1a97e0243dbc 4 : DB(DB0,DB1,DB2,DB3,DB4,DB5,DB6,DB7),RS(_RS), RW(_RW), E(_E) {
Bas 0:1a97e0243dbc 5
Bas 0:1a97e0243dbc 6 DB.output();
Bas 0:1a97e0243dbc 7 E.write(0);
Bas 0:1a97e0243dbc 8 RS.write(0);
Bas 0:1a97e0243dbc 9 RW.write(0);
Bas 0:1a97e0243dbc 10 InitDisplay();
Bas 0:1a97e0243dbc 11 }
Bas 0:1a97e0243dbc 12
Bas 0:1a97e0243dbc 13 unsigned int ST7920::ByteReadLCD() {
Bas 0:1a97e0243dbc 14 unsigned int data;
Bas 0:1a97e0243dbc 15
Bas 0:1a97e0243dbc 16 DB.input();
Bas 0:1a97e0243dbc 17 E.write(1);
Bas 0:1a97e0243dbc 18 data = DB.read();
Bas 0:1a97e0243dbc 19 E.write(0);
Bas 0:1a97e0243dbc 20 DB.output();
Bas 0:1a97e0243dbc 21
Bas 0:1a97e0243dbc 22 return data;
Bas 0:1a97e0243dbc 23 }
Bas 0:1a97e0243dbc 24
Bas 0:1a97e0243dbc 25 void ST7920::ByteWriteLCD(unsigned int data) {
Bas 0:1a97e0243dbc 26 DB.output();
Bas 0:1a97e0243dbc 27 E.write(1);
Bas 0:1a97e0243dbc 28 DB.write(data);
Bas 0:1a97e0243dbc 29 E.write(0);
Bas 0:1a97e0243dbc 30 }
Bas 0:1a97e0243dbc 31
Bas 0:1a97e0243dbc 32 void ST7920::WriteInstruction(unsigned int Command) {
Bas 0:1a97e0243dbc 33 ReadBusyFlag();
Bas 0:1a97e0243dbc 34 RS.write(0);
Bas 0:1a97e0243dbc 35 RW.write(0);
Bas 0:1a97e0243dbc 36 ByteWriteLCD(Command);
Bas 0:1a97e0243dbc 37 }
Bas 0:1a97e0243dbc 38
Bas 0:1a97e0243dbc 39 void ST7920::WriteRAM(unsigned int data) {
Bas 0:1a97e0243dbc 40 ReadBusyFlag();
Bas 0:1a97e0243dbc 41 RS.write(1);
Bas 0:1a97e0243dbc 42 RW.write(0);
Bas 0:1a97e0243dbc 43 ByteWriteLCD(data);
Bas 0:1a97e0243dbc 44 }
Bas 0:1a97e0243dbc 45
Bas 0:1a97e0243dbc 46 void ST7920::ReadBusyFlag() {
Bas 0:1a97e0243dbc 47 unsigned char data;
Bas 0:1a97e0243dbc 48
Bas 0:1a97e0243dbc 49 RS.write(0);
Bas 0:1a97e0243dbc 50 RW.write(1);
Bas 0:1a97e0243dbc 51 while ((data & 0x7F) == BUSY_FLAG_BF) {
Bas 0:1a97e0243dbc 52 data = ByteReadLCD();
Bas 0:1a97e0243dbc 53 }
Bas 0:1a97e0243dbc 54 }
Bas 0:1a97e0243dbc 55
Bas 0:1a97e0243dbc 56 unsigned int ST7920::Read_AC() {
Bas 0:1a97e0243dbc 57 RS.write(0);
Bas 0:1a97e0243dbc 58 RW.write(1);
Bas 0:1a97e0243dbc 59 return (ByteReadLCD() & 0x7F);
Bas 0:1a97e0243dbc 60 }
Bas 0:1a97e0243dbc 61
Bas 0:1a97e0243dbc 62 unsigned int ST7920::ReadRAM() {
Bas 0:1a97e0243dbc 63 ReadBusyFlag();
Bas 0:1a97e0243dbc 64 RS.write(1);
Bas 0:1a97e0243dbc 65 RW.write(1);
Bas 0:1a97e0243dbc 66 return ByteReadLCD();
Bas 0:1a97e0243dbc 67 }
Bas 0:1a97e0243dbc 68
Bas 0:1a97e0243dbc 69 void ST7920::InitDisplay() {
Bas 0:1a97e0243dbc 70 wait_ms(40); // wait 40ms
Bas 0:1a97e0243dbc 71 E.write(0);
Bas 0:1a97e0243dbc 72 WriteInstruction(FUNCTION_SET | DATA_LENGTH_DL); // 8 bits interface, RE=0
Bas 0:1a97e0243dbc 73 wait_us(100); // wait 100us
Bas 0:1a97e0243dbc 74 WriteInstruction(FUNCTION_SET | DATA_LENGTH_DL); // again
Bas 0:1a97e0243dbc 75 wait_us(37); // wait 37us
Bas 0:1a97e0243dbc 76 WriteInstruction(DISPLAY_CONTROL | DISPLAY_ON_D ); // display on
Bas 0:1a97e0243dbc 77 wait_us(100); // wait 100us
Bas 0:1a97e0243dbc 78 WriteInstruction(DISPLAY_CLEAR); // clear display
Bas 0:1a97e0243dbc 79 wait_ms(10); // wait 10ms
Bas 0:1a97e0243dbc 80 WriteInstruction(ENTRY_MODE_SET | INCREASE_DECREASE_ID); // move cursor right
Bas 0:1a97e0243dbc 81 wait_ms(10); // wait 10ms
Bas 0:1a97e0243dbc 82 WriteInstruction(RETURN_HOME);
Bas 0:1a97e0243dbc 83 SetGraphicsMode();
Bas 0:1a97e0243dbc 84 }
Bas 0:1a97e0243dbc 85
Bas 0:1a97e0243dbc 86 //************************************************************************************************
Bas 0:1a97e0243dbc 87 //public methodes
Bas 0:1a97e0243dbc 88 void ST7920::SetGraphicsMode() {
Bas 0:1a97e0243dbc 89 WriteInstruction(EXTENDED_FUNCTION_SET | DATA_LENGTH_DL);
Bas 0:1a97e0243dbc 90 WriteInstruction(EXTENDED_FUNCTION_SET | DATA_LENGTH_DL | EXTENDED_INSTRUCTION_RE); //RE=1 (Extended funtion set)
Bas 0:1a97e0243dbc 91 WriteInstruction(EXTENDED_FUNCTION_SET | DATA_LENGTH_DL | EXTENDED_INSTRUCTION_RE | GRAPHIC_ON_G);
Bas 0:1a97e0243dbc 92 }
Bas 0:1a97e0243dbc 93
Bas 0:1a97e0243dbc 94 void ST7920::SetTextMode() {
Bas 0:1a97e0243dbc 95 WriteInstruction(FUNCTION_SET | DATA_LENGTH_DL); // RE=0 (Basic funtion set)
Bas 0:1a97e0243dbc 96 }
Bas 0:1a97e0243dbc 97
Bas 0:1a97e0243dbc 98 void ST7920::ClearScreen() {
Bas 0:1a97e0243dbc 99 WriteInstruction(FUNCTION_SET | DATA_LENGTH_DL); // RE=0 (Basic funtion set)
Bas 0:1a97e0243dbc 100 WriteInstruction(DISPLAY_CLEAR);
Bas 0:1a97e0243dbc 101 }
Bas 0:1a97e0243dbc 102
Bas 0:1a97e0243dbc 103 void ST7920::ReturnHome() {
Bas 0:1a97e0243dbc 104 WriteInstruction(FUNCTION_SET | DATA_LENGTH_DL); //RE=0 (Basic funtion set)
Bas 0:1a97e0243dbc 105 WriteInstruction(RETURN_HOME);
Bas 0:1a97e0243dbc 106 }
Bas 0:1a97e0243dbc 107
Bas 0:1a97e0243dbc 108 void ST7920::Standby() {
Bas 0:1a97e0243dbc 109 WriteInstruction(EXTENDED_FUNCTION_SET | DATA_LENGTH_DL | EXTENDED_INSTRUCTION_RE); //RE=1 (Extended funtion set)
Bas 0:1a97e0243dbc 110 WriteInstruction(STANDBY);
Bas 0:1a97e0243dbc 111 }
Bas 0:1a97e0243dbc 112
Bas 0:1a97e0243dbc 113 //Basic text functions
Bas 0:1a97e0243dbc 114 void ST7920::DisplayString(int Row,int Column,unsigned char *ptr,int length) {
Bas 0:1a97e0243dbc 115 int i=0;
Bas 0:1a97e0243dbc 116
Bas 0:1a97e0243dbc 117 switch (Row) {
Bas 0:1a97e0243dbc 118 case 0:
Bas 0:1a97e0243dbc 119 Column|=0x80;
Bas 0:1a97e0243dbc 120 break;
Bas 0:1a97e0243dbc 121 case 1:
Bas 0:1a97e0243dbc 122 Column|=0x90;
Bas 0:1a97e0243dbc 123 break;
Bas 0:1a97e0243dbc 124 case 2:
Bas 0:1a97e0243dbc 125 Column|=0x88;
Bas 0:1a97e0243dbc 126 break;
Bas 0:1a97e0243dbc 127 case 3:
Bas 0:1a97e0243dbc 128 Column|=0x98;
Bas 0:1a97e0243dbc 129 break;
Bas 0:1a97e0243dbc 130 default:
Bas 0:1a97e0243dbc 131 Column=0x80;
Bas 0:1a97e0243dbc 132 break;
Bas 0:1a97e0243dbc 133 }
Bas 0:1a97e0243dbc 134
Bas 0:1a97e0243dbc 135 if (Column%2!=0) {
Bas 0:1a97e0243dbc 136 Column-=1;
Bas 0:1a97e0243dbc 137 i=1;
Bas 0:1a97e0243dbc 138 }
Bas 0:1a97e0243dbc 139 WriteInstruction((unsigned int)Column);
Bas 0:1a97e0243dbc 140
Bas 0:1a97e0243dbc 141 if (i==1) {
Bas 0:1a97e0243dbc 142 WriteRAM(' ');
Bas 0:1a97e0243dbc 143 }
Bas 0:1a97e0243dbc 144 for (i=0; i<length; i++) {
Bas 0:1a97e0243dbc 145 WriteRAM((unsigned int)ptr[i]);
Bas 0:1a97e0243dbc 146 }
Bas 0:1a97e0243dbc 147 }
Bas 0:1a97e0243dbc 148
Bas 0:1a97e0243dbc 149 void ST7920::DisplayChar(int Row,int Column,int inpChr) {
Bas 0:1a97e0243dbc 150 int i=0;
Bas 0:1a97e0243dbc 151
Bas 0:1a97e0243dbc 152 switch (Row) {
Bas 0:1a97e0243dbc 153 case 0:
Bas 0:1a97e0243dbc 154 Column|=0x80; // SET_DDRAM_ADDRESS
Bas 0:1a97e0243dbc 155 break;
Bas 0:1a97e0243dbc 156 case 1:
Bas 0:1a97e0243dbc 157 Column|=0x90;
Bas 0:1a97e0243dbc 158 break;
Bas 0:1a97e0243dbc 159 case 2:
Bas 0:1a97e0243dbc 160 Column|=0x88;
Bas 0:1a97e0243dbc 161 break;
Bas 0:1a97e0243dbc 162 case 3:
Bas 0:1a97e0243dbc 163 Column|=0x98;
Bas 0:1a97e0243dbc 164 break;
Bas 0:1a97e0243dbc 165 default:
Bas 0:1a97e0243dbc 166 Column=0x80;
Bas 0:1a97e0243dbc 167 break;
Bas 0:1a97e0243dbc 168 }
Bas 0:1a97e0243dbc 169
Bas 0:1a97e0243dbc 170 if (Column%2!=0) {
Bas 0:1a97e0243dbc 171 Column-=1;
Bas 0:1a97e0243dbc 172 i=1;
Bas 0:1a97e0243dbc 173 }
Bas 0:1a97e0243dbc 174 WriteInstruction((unsigned int)Column);
Bas 0:1a97e0243dbc 175
Bas 0:1a97e0243dbc 176 if (i==1) {
Bas 0:1a97e0243dbc 177 WriteRAM(' ');
Bas 0:1a97e0243dbc 178 }
Bas 0:1a97e0243dbc 179 WriteRAM((unsigned int)inpChr);
Bas 0:1a97e0243dbc 180 }
Bas 0:1a97e0243dbc 181
Bas 0:1a97e0243dbc 182 // Graphic functions
Bas 0:1a97e0243dbc 183 void ST7920::FillGDRAM(unsigned char *bitmap) {
Bas 0:1a97e0243dbc 184 unsigned char i, j, k ;
Bas 0:1a97e0243dbc 185
Bas 0:1a97e0243dbc 186 for ( i = 0 ; i < 2 ; i++ ) {
Bas 0:1a97e0243dbc 187 for ( j = 0 ; j < 32 ; j++ ) {
Bas 0:1a97e0243dbc 188 WriteInstruction(SET_GRAPHIC_RAM_ADDRESS | j) ;
Bas 0:1a97e0243dbc 189 if ( i == 0 ) {
Bas 0:1a97e0243dbc 190 WriteInstruction(SET_GRAPHIC_RAM_ADDRESS) ;
Bas 0:1a97e0243dbc 191 } else {
Bas 0:1a97e0243dbc 192 WriteInstruction(SET_GRAPHIC_RAM_ADDRESS | 0x08) ;
Bas 0:1a97e0243dbc 193 }
Bas 0:1a97e0243dbc 194 for ( k = 0 ; k < 16 ; k++ ) {
Bas 0:1a97e0243dbc 195 WriteRAM( *bitmap++ ) ;
Bas 0:1a97e0243dbc 196 }
Bas 0:1a97e0243dbc 197 }
Bas 0:1a97e0243dbc 198 }
Bas 0:1a97e0243dbc 199 }
Bas 0:1a97e0243dbc 200
Bas 0:1a97e0243dbc 201 void ST7920::FillGDRAM_Turned(unsigned char *bitmap) {
Bas 0:1a97e0243dbc 202 int i, j, k, m, offset_row, mask ;
Bas 0:1a97e0243dbc 203 unsigned char data;
Bas 0:1a97e0243dbc 204
Bas 0:1a97e0243dbc 205 for ( i = 0 ; i < 2 ; i++ ) { //upper and lower page
Bas 0:1a97e0243dbc 206 for ( j = 0 ; j < 32 ; j++ ) { //32 lines per page
Bas 0:1a97e0243dbc 207 WriteInstruction(SET_GRAPHIC_RAM_ADDRESS | j) ;
Bas 0:1a97e0243dbc 208 if ( i == 0 ) {
Bas 0:1a97e0243dbc 209 WriteInstruction(SET_GRAPHIC_RAM_ADDRESS) ;
Bas 0:1a97e0243dbc 210 } else {
Bas 0:1a97e0243dbc 211 WriteInstruction(SET_GRAPHIC_RAM_ADDRESS | 0x08) ;
Bas 0:1a97e0243dbc 212 }
Bas 0:1a97e0243dbc 213 mask=1<<(j%8); // extract bitnumber
Bas 0:1a97e0243dbc 214 //printf("mask: %d\r\n",mask);
Bas 0:1a97e0243dbc 215 for ( k = 0 ; k < 16 ; k++ ) { //16 bytes per line
Bas 0:1a97e0243dbc 216 offset_row=((i*32+j)/8)*128 + k*8; //y coordinate/8 = row 0-7 * 128 = byte offset, read 8 bytes
Bas 0:1a97e0243dbc 217 data=0;
Bas 0:1a97e0243dbc 218 for (m = 0 ; m < 8 ; m++) { // read 8 bytes from source
Bas 0:1a97e0243dbc 219
Bas 0:1a97e0243dbc 220 if ((bitmap[offset_row+m] & mask)) { //pixel = 1
Bas 0:1a97e0243dbc 221 data|=(128>>m);
Bas 0:1a97e0243dbc 222 }
Bas 0:1a97e0243dbc 223 }
Bas 0:1a97e0243dbc 224 WriteRAM(data) ;
Bas 0:1a97e0243dbc 225 }
Bas 0:1a97e0243dbc 226 }
Bas 0:1a97e0243dbc 227 }
Bas 0:1a97e0243dbc 228 }
Bas 0:1a97e0243dbc 229
Bas 0:1a97e0243dbc 230 void ST7920::ClearGDRAM() {
Bas 0:1a97e0243dbc 231 unsigned char i, j, k ;
Bas 0:1a97e0243dbc 232
Bas 0:1a97e0243dbc 233 for ( i = 0 ; i < 2 ; i++ ) {
Bas 0:1a97e0243dbc 234 for ( j = 0 ; j < 32 ; j++ ) {
Bas 0:1a97e0243dbc 235 WriteInstruction(SET_GRAPHIC_RAM_ADDRESS | j) ;
Bas 0:1a97e0243dbc 236 if ( i == 0 ) {
Bas 0:1a97e0243dbc 237 WriteInstruction(SET_GRAPHIC_RAM_ADDRESS) ;
Bas 0:1a97e0243dbc 238 } else {
Bas 0:1a97e0243dbc 239 WriteInstruction(SET_GRAPHIC_RAM_ADDRESS | 0x08) ;
Bas 0:1a97e0243dbc 240 }
Bas 0:1a97e0243dbc 241 for ( k = 0 ; k < 16 ; k++ ) {
Bas 0:1a97e0243dbc 242 WriteRAM(0);
Bas 0:1a97e0243dbc 243 }
Bas 0:1a97e0243dbc 244 }
Bas 0:1a97e0243dbc 245 }
Bas 0:1a97e0243dbc 246 }