I start to working with LCD ST7920
// define pins here
#define DATA_PORT PORTD
#define DATA_IN PIND
#define COMMAND_PORT PORTC
#define DATAPORT_DIR DDRD
#define COMMAND_DIR DDRC
#define RS 0b00000001; // PC0 binary equivalent of pin number
#define RW 0b00000010; // PC1
#define E 0b00000100; // PC2
#define RST 0b00001000; // PC3
#define delay_time 80
void highRS() {
COMMAND_PORT |= RS;
_delay_us(delay_time);
}
void lowRS() {
COMMAND_PORT &= ~RS;
_delay_us(delay_time);
}
void highRW() {
COMMAND_PORT |= RW;
_delay_us(delay_time);
}
void lowRW() {
COMMAND_PORT &= ~RW;
_delay_us(delay_time);
}
void highE() {
COMMAND_PORT |= E;
_delay_us(delay_time);
}
void lowE() {
COMMAND_PORT &= ~E;
_delay_us(delay_time);
}
void toggleE() {
highE();
lowE();
}
void highRST() {
COMMAND_PORT |= RST;
_delay_us(delay_time);
}
void lowRST() {
COMMAND_PORT &= ~RST;
_delay_us(delay_time);
}
// start graphic mode
void ST7920_graphicEnable(void) {
DATAPORT_DIR = 0xff;
_delay_ms(110);
lowE();
lowRS();
lowRW();
highRST();
DATA_PORT = 0x30; // set 8-bit interface
delay_ms(110);
toggleE();
_delay_ms(1);
DATA_PORT = 0x36; // Repeat with graphics bit set to on.
_delay_ms(110);
toggleE();
DATA_PORT = 0x0c; // display ON, cursor and blink OFF
_delay_ms(110);
toggleE();
DATA_PORT = 0x01; // clear display, reset address
_delay_ms(110);
toggleE();
DATA_PORT = 0x06; // display ON, no cursor
_delay_ms(110);
toggleE();
}
void ST7920_graphicFill(uint16_t value) {
uint8_t i, j;
for (i = 0; i < 64; i++) {
for (j = 0; j < 8; j++) {
ST7920_write2BytesXY(j, i, value);
}
}
}
void ST7920_write2BytesXY(int x, int y, uint16_t data) {
DATAPORT_DIR = 0xff; // set data port for output
lowE();
lowRS();
lowRW();
// convert coordinates to weirdly-arranged 128x64 screen (the ST7920 is mapped for 256x32 displays).
if (y > 31) {
y -= 32; // because there are only 31 addressable lines in the ST7920
x += 8; // so we overflow x (7 visible bytes per line) to reach the bottom half
}
x |= 0x80; // bit 7 signals that this is a data address write
y |= 0x80;
DATA_PORT = y; // set vertical DDRAM address
toggleE();
DATA_PORT = x; // set horizontal DDRAM address
toggleE();
highRS(); // signal for WRITE
DATA_PORT = (data >> 8); // set horizontal DDRAM address
toggleE();
DATA_PORT = data; // set vertical DDRAM address
toggleE();
}
uint16_t ST7920_read2Bytes(uint8_t type) {
uint8_t i, j = 0;
uint16_t temp;
DATAPORT_DIR = 0x00; // set data port for input
DATA_PORT = 0x00;
lowE();
if (type == 0) {
lowRS();
} else {
highRS();
}
highRW();
highE(); // toggle byte in
i = DATA_IN; // need I read this twice?
lowE();
highE();
i = DATA_IN;
lowE();
_delay_ms(1);
highE();
j = DATA_IN;
lowE();
temp = j;
temp = temp | (i << 8);
return(temp); // return byte read
}
void ST7920_gotoXY(uint8_t x, uint8_t y) {
DATAPORT_DIR = 0xff; // set data port for output
lowE();
lowRS();
lowRW();
// convert coordinates to weirdly-arranged 128x64 screen (the ST7920 is mapped for 256x32 displays).
if (y > 31) {
y -= 32; // because there are only 31 addressable lines in the ST7920
x += 8; // so we overflow x (7 visible bytes per line) to reach the bottom half
}
x |= 0x80; // bit 7 signals that this is a data address write
y |= 0x80;
DATA_PORT = y; // Set vertical DDRAM address
toggleE();
DATA_PORT = x; // Set horizontal DDRAM address
toggleE();
}
void ST7920_setPixel(uint8_t x, uint8_t y) {
uint8_t x_wd, x_pixel;
uint16_t temp;
uint16_t dot = 0x8000; // this will be rotated into it's correct position in the word
x_wd = x / 16; // find address of word with our pixel (x; 0-7)
x_pixel = x - (x_wd * 16); // get the modulo remainder; that's our pixel's position in the word
ST7920_gotoXY(x_wd, y);
temp = ST7920_read2Bytes(1); // read word from screen at that position
temp = (temp | (dot >> x_pixel)); // convert x_pixel into a bit position, 0-16
ST7920_write2BytesXY(x_wd, y, temp);
}
void ST7920_clearPixel(uint8_t x, uint8_t y) {
uint8_t x_wd, x_pixel;
uint16_t temp;
uint16_t dot = 0x7fff; // this will be rotated into it's correct position in the word
x_wd = x / 16; // find address of word with our pixel (x; 0-7)
x_pixel = x - (x_wd * 16); // get the modulo remainder; that's our pixel's position in the word
ST7920_gotoXY(x_wd, y);
temp = ST7920_read2Bytes(1); // read word from screen at that position
temp = (temp & (dot >> x_pixel)); // convert x_pixel into a bit position, 0-16
ST7920_write2BytesXY(x_wd, y, temp);
}
int main(void)
{
DATAPORT_DIR = 0xff; // set DATAPORT to output
DATA_PORT = 0x00; // set outputs to 0 initially
COMMAND_DIR = 0x07; // set command port to output
COMMAND_PORT = 0x00; // set outputs to 0 initially
ST7920_graphicEnable();
ST7920_graphicFill(0x0000);
ST7920_setPixel(0, 0);
ST7920_setPixel(0, 63);
ST7920_setPixel(127, 0);
ST7920_setPixel(127, 127);
while (1) {
}
}
When I switch power OFF/ON after LCD initializing, LCD displaing not correct view. I guess something wrong with init sequence. I can't find where I am make mistake)
