ST7920算是蠻常見的Arduino顯示LCD了，很多小型的機器都有它的身影，主要是因為它的尺寸夠大，還能內建中文，不過有分繁體和簡體，千萬別買錯了！
ST7920可以用的函式庫，基本上有兩款，一款是大大有名的u8g2，一款是輕巧型的LCD12864RSPI。u8g2雖然強大，但它無法使用ST7920的內建字庫；LCD12864RSPI雖然很陽春，只能顯示固定尺寸的文字，圖片也只能單張全畫面，但勝在簡單易用，我們先來試試這個函式庫吧！
首先請先下載LCD12864RSPI函式庫，並解壓縮到電腦中Arduino的Documents\Arduino\libraries目錄裡。
下載網址：
http://jmaker.banner.tw/doc/LCD12864RSPI.zip
線比I2C的LCD多一些，請依以下的指示接線：
- VSS=>GND
- VDD=>5V
- RS=>D8
- R/W=>D9
- E=>D3
- PSB=>GND
- BLA=>3.3V
- BLK=>GND
因為函式庫很單純，所以直接用它的範例LCD12864_test來修改。
#include "LCD12864RSPI.h"
#define AR_SIZE( a ) sizeof( a ) / sizeof( a[0] )
unsigned char show0[]= {0xB3,0xC7,0xB4,0xCB,0xB3,0xD0,0xA4,0x75}; //傑森創工的BIG5編碼
unsigned char show1[]="jmaker.com.tw";
unsigned char messageString[]={
0xB3, 0xD0,
0xAB, 0xC8,
0xAA, 0xBA,
0xA6, 0x6E,
0xAA, 0x42,
0xA4, 0xCD
};
//圖檔，必須是128x64，並且在繪圖軟體就要做成單色BMP，才能進Image2LCD轉檔，不然會顯示失敗！
unsigned char jmaker_bitmap[] = {
0X00,0X00,0X00,0X00,0X00,0X00,0X07,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,
0X00,0X00,0X00,0X00,0X00,0X00,0X07,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,
0X00,0X00,0X00,0X07,0X00,0X00,0X07,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,
0X00,0X00,0X00,0X0F,0X80,0X00,0X07,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,
0X00,0X00,0X00,0X1F,0XC0,0X00,0X07,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,
0X00,0X00,0X00,0X1F,0XC0,0X00,0X07,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,
0X00,0X78,0X00,0X0F,0X80,0X00,0X07,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,
0X00,0X7E,0X00,0X0F,0X00,0X00,0X07,0XFF,0XFE,0X63,0XF9,0XFF,0XF8,0XFF,0XFF,0XFF,
0X00,0XFF,0XC0,0X04,0X00,0X00,0X07,0XFF,0XFC,0X67,0XF9,0XFF,0XF8,0XFF,0XFF,0XFF,
0X04,0XFF,0XF0,0X08,0X00,0X00,0X07,0XFF,0XFC,0X61,0XF1,0XF8,0X00,0X00,0XFF,0XFF,
0X0C,0XFF,0XFE,0X08,0X00,0X00,0X07,0XFF,0XFC,0XC0,0X00,0X70,0X00,0X00,0XFF,0XFF,
0X0D,0XFF,0XFF,0X98,0X00,0X00,0X07,0XFF,0XF8,0X88,0X00,0X78,0X40,0X10,0XFF,0XFF,
0X1D,0XFF,0XFF,0XF0,0X00,0X00,0X07,0XFF,0XF9,0X9C,0X91,0XFF,0XC0,0X1F,0XFF,0XFF,
0X19,0XF8,0X7F,0XFC,0X00,0X00,0X07,0XFF,0XF1,0X08,0X99,0XFF,0X08,0X87,0XFF,0XFF,
0X39,0XE0,0X1F,0XFF,0X80,0X00,0X07,0XFF,0XE1,0X21,0X99,0XF8,0X18,0XC0,0XFF,0XFF,
0X3B,0XC0,0X0F,0XFF,0XE0,0X00,0X07,0XFF,0XE1,0XE3,0X00,0X70,0X78,0XF0,0X7F,0XFF,
0X73,0XC0,0X0F,0XFF,0XFC,0X00,0X07,0XFF,0XC1,0XE2,0X00,0X70,0X78,0XE8,0X7F,0XFF,
0X73,0X80,0X07,0XFF,0XFF,0X00,0X07,0XFF,0XC1,0XC7,0XC0,0X7F,0X39,0XC7,0XFF,0XFF,
0X77,0X80,0X07,0XFF,0XFF,0XE0,0X07,0XFF,0XE9,0X0F,0XF9,0XFF,0X3F,0XC7,0XFF,0XFF,
0X77,0X80,0X07,0XFF,0XFF,0XFC,0X07,0XFF,0XF9,0X1E,0X39,0XF0,0X06,0X00,0X7F,0XFF,
0X07,0X80,0X07,0XFF,0XFF,0XFC,0X07,0XFF,0XF9,0XBE,0X3F,0XE0,0X00,0X00,0X7F,0XFF,
0X0F,0XC0,0X0F,0XFF,0XFF,0XF8,0X07,0XFF,0XF9,0X80,0X00,0X70,0X06,0X00,0X7F,0XFF,
0X0F,0XC0,0X0F,0XF8,0X3F,0XF8,0X07,0XFF,0XF9,0X80,0X00,0X7E,0X0F,0X83,0XFF,0XFF,
0X1F,0XE0,0X1F,0XF0,0X1F,0XF8,0X07,0XFF,0XF9,0XF8,0X1F,0XFC,0X07,0X01,0XFF,0XFF,
0X1F,0XF8,0X7F,0XE0,0X1F,0XF0,0X07,0XFF,0XF9,0XF0,0X0F,0XF8,0X26,0X00,0XFF,0XFF,
0X0F,0XFF,0XFF,0XE0,0X0F,0XF6,0X07,0XFF,0XF9,0XE2,0X63,0XF1,0X34,0X4C,0X7F,0XFF,
0X03,0XFF,0XFF,0XE0,0X0F,0XE6,0X07,0XFF,0XF9,0X86,0X20,0X63,0X38,0XC6,0X3F,0XFF,
0X10,0X7F,0XFF,0XE0,0X0F,0XEE,0X07,0XFF,0XF9,0X0E,0X38,0X67,0X39,0XC7,0X7F,0XFF,
0X3C,0X0F,0XFF,0XF0,0X1F,0XCC,0X07,0XFF,0XF9,0XBE,0X3E,0XFF,0X3F,0XC7,0XFF,0XFF,
0X3F,0X83,0XFF,0XF8,0X3F,0XDC,0X07,0XFF,0XF9,0XFE,0X3F,0XFF,0X3F,0XC7,0XFF,0XFF,
0X7F,0XE0,0X7F,0XFC,0XFF,0X9C,0X07,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,
0X7F,0XFC,0X1F,0XFF,0XFF,0XB8,0X07,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,
0X1F,0XFF,0X03,0XFF,0XFF,0XB8,0X07,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,
0X07,0XFF,0XE0,0X7F,0XFF,0X30,0XC7,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,
0X00,0XFF,0XFC,0X1F,0XFF,0X71,0XF7,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,
0X60,0X3F,0XFF,0X03,0XFF,0X01,0XE7,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,
0X78,0X07,0XFF,0XE0,0XFE,0X01,0XC7,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,
0X79,0XC3,0XFF,0XF8,0X1E,0X01,0XC7,0XFF,0XFF,0X9F,0XFD,0XFF,0XFF,0XFF,0XFF,0XFF,
0X19,0XF0,0XFF,0XFF,0X04,0X03,0XC7,0XFF,0XFF,0X1F,0XF8,0XFF,0XFF,0XFF,0XFF,0XFF,
0X19,0X9E,0X1F,0XFF,0XC0,0X03,0XF7,0XFF,0XFE,0X0F,0X98,0XFF,0XFF,0XFF,0XFF,0XFF,
0X7D,0X87,0X84,0XFF,0XF8,0X03,0XF7,0XFF,0XFC,0X43,0X88,0XF8,0X00,0X00,0XFF,0XFF,
0X7C,0XF0,0XF0,0X3F,0XF8,0X01,0XF7,0XFF,0XF8,0X60,0X8C,0XF8,0X00,0X00,0XFF,0XFF,
0X7C,0X3C,0X3C,0X0F,0XF8,0X00,0X77,0XFF,0XE0,0X00,0X98,0XF8,0X00,0X81,0XFF,0XFF,
0X7F,0X07,0X87,0X81,0XF0,0X00,0X07,0XFF,0XE2,0X0C,0X98,0XFF,0XF8,0XFF,0XFF,0XFF,
0X7F,0XE1,0XE1,0XE0,0X30,0X01,0X87,0XFF,0XE3,0X6F,0X98,0XFF,0XF8,0XFF,0XFF,0XFF,
0X7F,0XFC,0X3C,0X60,0X00,0X00,0XF7,0XFF,0XF8,0X01,0X98,0XFF,0XF8,0XFF,0XFF,0XFF,
0X7F,0XC7,0X0F,0XC6,0X00,0X06,0X77,0XFF,0XF8,0X01,0X98,0XFF,0XF8,0XFF,0XFF,0XFF,
0X7F,0XC1,0XC1,0XCF,0X80,0X0F,0X07,0XFF,0XF8,0XD1,0X98,0XFF,0XF8,0XFF,0XFF,0XFF,
0X7F,0X80,0X38,0X1F,0XE0,0X0F,0X87,0XFF,0XF8,0X01,0X98,0XFF,0XF8,0XFF,0XFF,0XFF,
0X7F,0X80,0X0E,0X38,0XE0,0XCF,0X87,0XFF,0XF8,0X01,0X98,0XFF,0XF8,0XFF,0XFF,0XFF,
0X7F,0XE0,0X0F,0XF8,0XC9,0XE7,0X07,0XFF,0XF9,0XF1,0X98,0XFF,0XF8,0XFF,0XFF,0XFF,
0X7F,0XF8,0X0F,0XFF,0XCD,0XE6,0X07,0XFF,0XF0,0X01,0X98,0XFF,0XF8,0XFF,0XFF,0XFF,
0X7F,0X18,0X1F,0XFF,0X9D,0XF0,0X07,0XFF,0XF0,0X03,0X88,0XFF,0XF8,0XFF,0XFF,0XFF,
0X7F,0X10,0XFF,0XFF,0X9D,0XC0,0X07,0XFF,0XF1,0XFF,0X98,0XFF,0XF8,0XFF,0XFF,0XFF,
0X7E,0X10,0XFF,0XFF,0X3C,0X00,0X07,0XFF,0XF0,0X01,0XFC,0XFF,0XF8,0XFF,0XFF,0XFF,
0X7E,0X00,0XFF,0XFF,0X78,0X00,0X07,0XFF,0XE0,0X00,0XFC,0XF0,0X00,0X00,0X7F,0XFF,
0X7E,0X01,0XFF,0XFE,0X70,0X00,0X07,0XFF,0XE2,0X78,0XF8,0XE0,0X00,0X00,0X7F,0XFF,
0X7F,0X01,0XFF,0XFC,0X40,0X00,0X07,0XFF,0XC6,0X01,0XC0,0XF0,0X00,0X00,0X7F,0XFF,
0X7F,0XC3,0XFF,0XFC,0X00,0X00,0X07,0XFF,0XE6,0X00,0XC0,0XFF,0XFF,0XFF,0XFF,0XFF,
0X7F,0XFB,0XFF,0XF8,0X00,0X00,0X07,0XFF,0XFE,0X31,0XE1,0XFF,0XFF,0XFF,0XFF,0XFF,
0X7F,0XFF,0XFF,0XF8,0X00,0X00,0X07,0XFF,0XFE,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,
0X7F,0XFF,0XFE,0XF0,0X00,0X00,0X07,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,
0X7F,0XFF,0XFC,0X70,0X00,0X00,0X07,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,
0X00,0X00,0X00,0X00,0X00,0X00,0X07,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,
};
void setup()
{
LCDA.Initialise(); // 初始化
delay(100);
LCDA.DrawFullScreen(jmaker_bitmap); //顯示全畫面圖片
delay(2000);
LCDA.CLEAR();//清除畫面
delay(100); //這個延遲是必要的，不然下一個指令會有問題。
LCDA.DisplayString(0,2,show0,AR_SIZE(show0));//第一行第三格開始顯示文字
delay(100);
LCDA.DisplayString(1,1,messageString,AR_SIZE(messageString));//第二行第二格開始顯示文字
delay(100);
LCDA.DisplayString(3,1,show1,AR_SIZE(show1));//第三行第二格開始，显示傑森創工的網址。
delay(5000);
}
void loop()
{
}
其實只有兩個主要的函式：
- LCDA.DrawFullScreen()，顯示全螢幕圖片，所以圖片必須是128x64
- LCDA.DisplayString()，顯示文字。
顯示英文很簡單，直接把字串放進DisplayString()裡就行了！
LCDA.DisplayString(3,1,"jmaker.com.tw",13);
這行指的是從第四行第二格開始顯示文字，而文字的長度是13。
如果是中文就要小麻煩一下，先把你要顯示的中文，轉成Big5碼，網路上有不少線上服務，大家可以找找！
線上中文轉Big5碼：
http://billor.chsh.chc.edu.tw/php/Tools/qBig5.php
以傑字來說，Big5碼是B3C7，必須把它拆成 0xB3,0xC7 。所以這行就是把「傑森創工」Big5碼寫成了陣列：
unsigned char show0[]= {0xB3,0xC7,0xB4,0xCB,0xB3,0xD0,0xA4,0x75};
要顯示它很簡單：
LCDA.DisplayString(0,2,show0,AR_SIZE(show0));
第一行第三格開始顯示文字，文字長度用算的就行了。
至於圖片，首先到繪圖軟體先畫面，以Photoshop為例，記要做成單色BMP，才能進Image2LCD轉檔，不然會顯示失敗！
LCDA.DrawFullScreen(jmaker_bitmap);
LCD12864RSPI函式庫處理圖片很簡單，就是畫一張全版的圖片，尺寸就是128x64，好處就是簡單啦！
如果要部份地址是圖片，部份是文字呢？很簡單，製作圖片時留下空白，圖片先放上LCD，再把文字寫到空白的地方就可以囉！
如果你覺得LCD12864RSPI函式庫太陽春了，傑森會在之後介紹u8g2用在ST7920上，變化會多一些，請期待喔！