GLCD 128×64 ST7920 interfacing with STM32

void SendByteSPI(uint8_t byte)

void ST7920_SendCmd (uint8_t cmd)
{

	HAL_GPIO_WritePin(CS_PORT, CS_PIN, GPIO_PIN_SET);  // PUll the CS high

	SendByteSPI(0xf8+(0<<1));  // send the SYNC + RS(0)
	SendByteSPI(cmd&0xf0);  // send the higher nibble first
	SendByteSPI((cmd<<4)&0xf0);  // send the lower nibble
	delay_us(50);

	HAL_GPIO_WritePin(CS_PORT, CS_PIN, GPIO_PIN_RESET);  // PUll the CS LOW

}

void ST7920_SendData (uint8_t data)
{
	HAL_GPIO_WritePin(CS_PORT, CS_PIN, GPIO_PIN_SET);  // PUll the CS high

	SendByteSPI(0xf8+(1<<1));  // send the SYNC + RS(1)
	SendByteSPI(data&0xf0);  // send the higher nibble first
	SendByteSPI((data<<4)&0xf0);  // send the lower nibble
	delay_us(50);
	HAL_GPIO_WritePin(CS_PORT, CS_PIN, GPIO_PIN_RESET);  // PUll the CS LOW
}

void ST7920_Init (void)
{
	HAL_GPIO_WritePin(RST_PORT, RST_PIN, GPIO_PIN_RESET);  // RESET=0
	HAL_Delay(10);   // wait for 10ms
	HAL_GPIO_WritePin(RST_PORT, RST_PIN, GPIO_PIN_SET);  // RESET=1

	HAL_Delay(50);   //wait for >40 ms


	ST7920_SendCmd(0x30);  // 8bit mode
	delay_us(110);  //  >100us delay

	ST7920_SendCmd(0x30);  // 8bit mode
	delay_us(40);  // >37us delay

	ST7920_SendCmd(0x08);  // D=0, C=0, B=0
	delay_us(110);  // >100us delay

	ST7920_SendCmd(0x01);  // clear screen
	HAL_Delay(12);  // >10 ms delay


	ST7920_SendCmd(0x06);  // cursor increment right no shift
	HAL_Delay(1);  // 1ms delay

	ST7920_SendCmd(0x0C);  // D=1, C=0, B=0
    HAL_Delay(1);  // 1ms delay

	ST7920_SendCmd(0x02);  // return to home
	HAL_Delay(1);  // 1ms delay

}

void ST7920_GraphicMode ()   
{
  ST7920_SendCmd(0x30);  // 8 bit mode
  HAL_Delay (1);
  ST7920_SendCmd(0x34);  // switch to Extended instructions
  HAL_Delay (1);
  ST7920_SendCmd(0x36);  // enable graphics
  HAL_Delay (1);
}

void ST7920_DrawBitmap(const unsigned char* graphic)
{
	uint8_t x, y;
	for(y = 0; y < 64; y++)
	{
		if(y < 32)
		{
			for(x = 0; x < 8; x++)	/ Draws top half of the screen.
			{			
                 		// In extended instruction mode, vertical and horizontal coordinates must be specified before sending data in.
				ST7920_SendCmd(0x80 | y);	// Vertical coordinate of the screen is specified first. (0-31)
				ST7920_SendCmd(0x80 | x);	// Then horizontal coordinate of the screen is specified. (0-8)
				ST7920_SendData(graphic[2*x + 16*y]);	// Data to the upper byte is sent to the coordinate.
				ST7920_SendData(graphic[2*x+1 + 16*y]);	// Data to the lower byte is sent to the coordinate.
			}
		}
		else
		{
			for(x = 0; x < 8; x++)	// Draws bottom half of the screen.
			{
                           // Actions performed as same as the upper half screen.
			   ST7920_SendCmd(0x80 | (y-32));// Vertical coordinate must be scaled back to 0-31 as it is dealing with another half of the screen.
			  ST7920_SendCmd(0x88 | x);
			  ST7920_SendData(graphic[2*x + 16*y]);
			  ST7920_SendData(graphic[2*x+1 + 16*y]);
			}
		}

	}
}