Bas van Drunen Littel
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
Diff: st7920.cpp
- Revision:
- 0:1a97e0243dbc
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/st7920.cpp Fri Jun 29 22:47:51 2012 +0000
@@ -0,0 +1,246 @@
+#include "st7920.h"
+
+ST7920::ST7920 (PinName _RS,PinName _RW, PinName _E, PinName DB0, PinName DB1, PinName DB2, PinName DB3, PinName DB4, PinName DB5, PinName DB6, PinName DB7)
+ : DB(DB0,DB1,DB2,DB3,DB4,DB5,DB6,DB7),RS(_RS), RW(_RW), E(_E) {
+
+ DB.output();
+ E.write(0);
+ RS.write(0);
+ RW.write(0);
+ InitDisplay();
+}
+
+unsigned int ST7920::ByteReadLCD() {
+ unsigned int data;
+
+ DB.input();
+ E.write(1);
+ data = DB.read();
+ E.write(0);
+ DB.output();
+
+ return data;
+}
+
+void ST7920::ByteWriteLCD(unsigned int data) {
+ DB.output();
+ E.write(1);
+ DB.write(data);
+ E.write(0);
+}
+
+void ST7920::WriteInstruction(unsigned int Command) {
+ ReadBusyFlag();
+ RS.write(0);
+ RW.write(0);
+ ByteWriteLCD(Command);
+}
+
+void ST7920::WriteRAM(unsigned int data) {
+ ReadBusyFlag();
+ RS.write(1);
+ RW.write(0);
+ ByteWriteLCD(data);
+}
+
+void ST7920::ReadBusyFlag() {
+ unsigned char data;
+
+ RS.write(0);
+ RW.write(1);
+ while ((data & 0x7F) == BUSY_FLAG_BF) {
+ data = ByteReadLCD();
+ }
+}
+
+unsigned int ST7920::Read_AC() {
+ RS.write(0);
+ RW.write(1);
+ return (ByteReadLCD() & 0x7F);
+}
+
+unsigned int ST7920::ReadRAM() {
+ ReadBusyFlag();
+ RS.write(1);
+ RW.write(1);
+ return ByteReadLCD();
+}
+
+void ST7920::InitDisplay() {
+ wait_ms(40); // wait 40ms
+ E.write(0);
+ WriteInstruction(FUNCTION_SET | DATA_LENGTH_DL); // 8 bits interface, RE=0
+ wait_us(100); // wait 100us
+ WriteInstruction(FUNCTION_SET | DATA_LENGTH_DL); // again
+ wait_us(37); // wait 37us
+ WriteInstruction(DISPLAY_CONTROL | DISPLAY_ON_D ); // display on
+ wait_us(100); // wait 100us
+ WriteInstruction(DISPLAY_CLEAR); // clear display
+ wait_ms(10); // wait 10ms
+ WriteInstruction(ENTRY_MODE_SET | INCREASE_DECREASE_ID); // move cursor right
+ wait_ms(10); // wait 10ms
+ WriteInstruction(RETURN_HOME);
+ SetGraphicsMode();
+}
+
+//************************************************************************************************
+//public methodes
+void ST7920::SetGraphicsMode() {
+ WriteInstruction(EXTENDED_FUNCTION_SET | DATA_LENGTH_DL);
+ WriteInstruction(EXTENDED_FUNCTION_SET | DATA_LENGTH_DL | EXTENDED_INSTRUCTION_RE); //RE=1 (Extended funtion set)
+ WriteInstruction(EXTENDED_FUNCTION_SET | DATA_LENGTH_DL | EXTENDED_INSTRUCTION_RE | GRAPHIC_ON_G);
+}
+
+void ST7920::SetTextMode() {
+ WriteInstruction(FUNCTION_SET | DATA_LENGTH_DL); // RE=0 (Basic funtion set)
+}
+
+void ST7920::ClearScreen() {
+ WriteInstruction(FUNCTION_SET | DATA_LENGTH_DL); // RE=0 (Basic funtion set)
+ WriteInstruction(DISPLAY_CLEAR);
+}
+
+void ST7920::ReturnHome() {
+ WriteInstruction(FUNCTION_SET | DATA_LENGTH_DL); //RE=0 (Basic funtion set)
+ WriteInstruction(RETURN_HOME);
+}
+
+void ST7920::Standby() {
+ WriteInstruction(EXTENDED_FUNCTION_SET | DATA_LENGTH_DL | EXTENDED_INSTRUCTION_RE); //RE=1 (Extended funtion set)
+ WriteInstruction(STANDBY);
+}
+
+//Basic text functions
+void ST7920::DisplayString(int Row,int Column,unsigned char *ptr,int length) {
+ int i=0;
+
+ switch (Row) {
+ case 0:
+ Column|=0x80;
+ break;
+ case 1:
+ Column|=0x90;
+ break;
+ case 2:
+ Column|=0x88;
+ break;
+ case 3:
+ Column|=0x98;
+ break;
+ default:
+ Column=0x80;
+ break;
+ }
+
+ if (Column%2!=0) {
+ Column-=1;
+ i=1;
+ }
+ WriteInstruction((unsigned int)Column);
+
+ if (i==1) {
+ WriteRAM(' ');
+ }
+ for (i=0; i<length; i++) {
+ WriteRAM((unsigned int)ptr[i]);
+ }
+}
+
+void ST7920::DisplayChar(int Row,int Column,int inpChr) {
+ int i=0;
+
+ switch (Row) {
+ case 0:
+ Column|=0x80; // SET_DDRAM_ADDRESS
+ break;
+ case 1:
+ Column|=0x90;
+ break;
+ case 2:
+ Column|=0x88;
+ break;
+ case 3:
+ Column|=0x98;
+ break;
+ default:
+ Column=0x80;
+ break;
+ }
+
+ if (Column%2!=0) {
+ Column-=1;
+ i=1;
+ }
+ WriteInstruction((unsigned int)Column);
+
+ if (i==1) {
+ WriteRAM(' ');
+ }
+ WriteRAM((unsigned int)inpChr);
+}
+
+// Graphic functions
+void ST7920::FillGDRAM(unsigned char *bitmap) {
+ unsigned char i, j, k ;
+
+ for ( i = 0 ; i < 2 ; i++ ) {
+ for ( j = 0 ; j < 32 ; j++ ) {
+ WriteInstruction(SET_GRAPHIC_RAM_ADDRESS | j) ;
+ if ( i == 0 ) {
+ WriteInstruction(SET_GRAPHIC_RAM_ADDRESS) ;
+ } else {
+ WriteInstruction(SET_GRAPHIC_RAM_ADDRESS | 0x08) ;
+ }
+ for ( k = 0 ; k < 16 ; k++ ) {
+ WriteRAM( *bitmap++ ) ;
+ }
+ }
+ }
+}
+
+void ST7920::FillGDRAM_Turned(unsigned char *bitmap) {
+ int i, j, k, m, offset_row, mask ;
+ unsigned char data;
+
+ for ( i = 0 ; i < 2 ; i++ ) { //upper and lower page
+ for ( j = 0 ; j < 32 ; j++ ) { //32 lines per page
+ WriteInstruction(SET_GRAPHIC_RAM_ADDRESS | j) ;
+ if ( i == 0 ) {
+ WriteInstruction(SET_GRAPHIC_RAM_ADDRESS) ;
+ } else {
+ WriteInstruction(SET_GRAPHIC_RAM_ADDRESS | 0x08) ;
+ }
+ mask=1<<(j%8); // extract bitnumber
+ //printf("mask: %d\r\n",mask);
+ for ( k = 0 ; k < 16 ; k++ ) { //16 bytes per line
+ offset_row=((i*32+j)/8)*128 + k*8; //y coordinate/8 = row 0-7 * 128 = byte offset, read 8 bytes
+ data=0;
+ for (m = 0 ; m < 8 ; m++) { // read 8 bytes from source
+
+ if ((bitmap[offset_row+m] & mask)) { //pixel = 1
+ data|=(128>>m);
+ }
+ }
+ WriteRAM(data) ;
+ }
+ }
+ }
+}
+
+void ST7920::ClearGDRAM() {
+ unsigned char i, j, k ;
+
+ for ( i = 0 ; i < 2 ; i++ ) {
+ for ( j = 0 ; j < 32 ; j++ ) {
+ WriteInstruction(SET_GRAPHIC_RAM_ADDRESS | j) ;
+ if ( i == 0 ) {
+ WriteInstruction(SET_GRAPHIC_RAM_ADDRESS) ;
+ } else {
+ WriteInstruction(SET_GRAPHIC_RAM_ADDRESS | 0x08) ;
+ }
+ for ( k = 0 ; k < 16 ; k++ ) {
+ WriteRAM(0);
+ }
+ }
+ }
+}