前言
在以前用wiringPi写过驱动Nokia液晶的例子《(十六)树莓派3B+ wiringPi库的使用–硬件SPI驱动NOKIA5110液晶》。现在使用的是Node.js驱动这个显示屏。
简介
Nokia5110液晶屏现在买到的都是之前Nokia5110手机的拆机屏幕，液晶驱动芯片是PCD8544。
1.液晶屏原理图
结合实物看，这个液晶屏的对外接口都是很简单的。
2.PCD8544芯片
特征
单芯片 LCD 控制/驱动48 行，84 列输出显示数据 RAM 48*84 位芯片集成:——LCD 电压发生器(也可以使用外部电压供应)
——LCD偏置电压发生器
——振荡器不需要外接元件(也可以使用外部时钟)外部 RES(复位)输入引脚串行界面最高 4.0Mbits/SCMOS 兼容输入混合速率:48逻辑电压范围 VDD 到 VSS:2.7V~3.3V显示电压范围 VLCD 到 VSS:
——6.0~8.5V LCD内部电压发生器(充许电压发生器)
——6.0~9.0V LCD 外部电压供应(电压发生器关闭)低功耗，适用于电池供电系统关于 VLCD 的温度补偿使用温度范围:-25~70°C
概述
PCD8544 是一块低功耗的 CMOS LCD 控制驱动器，设计为驱动
48 行 84 列的图形显示。所有必须的显示功能集成在一块芯片上，包 括 LCD 电压及偏置电压发生器，只需很少外部元件且功耗小。
PCD8544 与微控制器的接口使用串行总线。
关于芯片的更多信息，大家可以去看芯片的数据手册。
驱动显示
这里的驱动显示使用的rpio这个库，之前也有使用的。7.树莓派3B+点亮第一个LED
let rpio = require('rpio');let font = require('./font');let os = require("os");// 定义NOKIA5110 屏幕的引脚和树莓派GPIO的连接关系const Nokia5110_pins = {RST: 40, // 复位引脚 低电平有效CE: 24, // 片选引脚 低电平有效DC: 38, // 数据/指令选择 1：写数据 0：写命令DIN: 19, // 串行数据线CLK: 23, // 串行时钟线}// 寻址 const NOKIA5110_address = {x_col_addr: 0x80, // 定位列 地址 0-83y_row_addr: 0x40 // 定位行 地址 0-5}// 端口初始化function gpioInit(){rpio.init({gpiomem: false});rpio.open(Nokia5110_pins.RST, rpio.OUTPUT); // 设置为输出 初始为低电平rpio.open(Nokia5110_pins.CE, rpio.OUTPUT); // 设置为输出 初始为低电平rpio.open(Nokia5110_pins.DC, rpio.OUTPUT); // 设置为输出 初始为低电平}// SPI初始化function spiInit(){gpioInit();rpio.spiBegin();rpio.spiChipSelect(0); /* Use CE0 */// rpio.spiSetCSPolarity(0, rpio.HIGH); /* PCD8544 chip select is active-low */rpio.spiSetClockDivider(128); /* PCD8544 最大 4MHz, 250MHz / 64 = 3.9MHz */rpio.spiSetDataMode(0);}// 往LCD写入数据// wbyte: 需要写入的数据// dat_cmd: 1-数据 0-命令 function lcd_writeByte(wbyte, dat_cmd){let wb = Buffer.from([wbyte])if (dat_cmd == 1) {// 写数据rpio.write(Nokia5110_pins.DC, rpio.HIGH); // 输高电电平}else {// 写命令rpio.write(Nokia5110_pins.DC, rpio.LOW); // 输出低电平}rpio.spiWrite(wb, wb.length);}// 液晶清屏function lcd_clear(){lcd_writeByte(NOKIA5110_address.x_col_addr,0);lcd_writeByte(NOKIA5110_address.y_row_addr,0);// 84*48的LCD点阵液晶 那么84x48=504for(i = 0; i < 504; i ++){lcd_writeByte(0,1);}}// 显示字节定位// x: x轴坐标 0-83// y: y轴坐标 0-5function lcd_pos_byte(x,y){x |= NOKIA5110_address.x_col_addr;y |= NOKIA5110_address.y_row_addr;lcd_writeByte(x,0);lcd_writeByte(y,0);}// 显示一个6*8字符// x: x轴坐标 0-13// y: y轴坐标 0-5function lcd_show_char(x, y, str=''){x = x * 6;lcd_pos_byte(x,y);let fontData = font[str];for(i = 0; i < 6; i ++){lcd_writeByte(fontData[i],1);}}// 显示字符串// x: x轴坐标 0-13// y: y轴坐标 0-5function lcd_show_string(x, y, str=''){for (let i = 0; i < str.length; i++) {lcd_show_char(x++, y, str.charAt(i));if(x == 14){x = 0; y ++;}if(y == 6){y = 0;}}}// 初始化液晶function lcd_init(){gpioInit();spiInit();rpio.write(Nokia5110_pins.RST, rpio.LOW); // 液晶复位rpio.msleep(500);rpio.write(Nokia5110_pins.RST, rpio.HIGH); // 液晶复位lcd_writeByte(0x21,0); // 工作模式 水平寻址 扩展指令lcd_writeByte(0x06,0); // VLCD温度系数2lcd_writeByte(0x13,0); // 设置偏置系统 1:48lcd_writeByte(0xc8,0); // 设置对比度lcd_writeByte(0x20,0); // 工作模式 水平寻址 常规指令lcd_writeByte(0x0c,0); // 普通模式lcd_clear(); // 清屏}function main(){lcd_init();lcd_show_string(0, 0,'0:' + os.hostname());lcd_show_string(0, 1,'1:' + os.type());lcd_show_string(0, 2,'2:' + os.platform());lcd_show_string(0, 3,'3:' + os.release());lcd_show_string(0, 4,'4:' + os.totalmem());lcd_show_string(0, 5,'5:' + os.freemem());}main()
font.js文件是字库数据
let font = {' ': [0x00,0x00,0x00,0x00,0x00,0x00],// (0)'!': [0x00,0x00,0x00,0x4F,0x00,0x00],//!(1)'"': [0x00,0x00,0x07,0x00,0x07,0x00],//"(2)'#': [0x00,0x14,0x7F,0x14,0x7F,0x14],//#(3)'$': [0x00,0x24,0x2A,0x7F,0x2A,0x12],//$(4)'%': [0x00,0x23,0x13,0x08,0x64,0x62],//%(5)'&': [0x00,0x36,0x49,0x55,0x22,0x50],//&(6)"'": [0x00,0x00,0x05,0x03,0x00,0x00],//'(7)'(': [0x00,0x00,0x1C,0x22,0x41,0x00],//((8)')': [0x00,0x00,0x41,0x22,0x1C,0x00],//)(9)'*': [0x00,0x14,0x08,0x3E,0x08,0x14],//*(10)'+': [0x00,0x08,0x08,0x3E,0x08,0x08],//+(11)',': [0x00,0x00,0x50,0x30,0x00,0x00],//,(12)'-': [0x00,0x08,0x08,0x08,0x08,0x08],//-(13)'.': [0x00,0x00,0x60,0x60,0x00,0x00],//.(14)'/': [0x00,0x20,0x10,0x08,0x04,0x02],///(15)'0': [0x00,0x3E,0x51,0x49,0x45,0x3E],//0(16)'1': [0x00,0x00,0x42,0x7F,0x40,0x00],//1(17)'2': [0x00,0x42,0x61,0x51,0x49,0x46],//2(18)'3': [0x00,0x21,0x41,0x45,0x4B,0x31],//3(19)'4': [0x00,0x18,0x14,0x12,0x7F,0x10],//4(20)'5': [0x00,0x27,0x45,0x45,0x45,0x39],//5(21)'6': [0x00,0x3C,0x4A,0x49,0x49,0x30],//6(22)'7': [0x00,0x01,0x71,0x09,0x05,0x03],//7(23)'8': [0x00,0x36,0x49,0x49,0x49,0x36],//8(24)'9': [0x00,0x06,0x49,0x49,0x29,0x1E],//9(25)':': [0x00,0x00,0x36,0x36,0x00,0x00],//:(26)';': [0x00,0x00,0x56,0x36,0x00,0x00],//;(27)'<': [0x00,0x08,0x14,0x22,0x41,0x00],//<(28)'=': [0x00,0x14,0x14,0x14,0x14,0x14],//=(29)'>': [0x00,0x00,0x41,0x22,0x14,0x08],//>(30)'?': [0x00,0x02,0x01,0x51,0x09,0x06],//?(31)'@': [0x00,0x32,0x49,0x79,0x41,0x3E],//@(32)'A': [0x00,0x7E,0x11,0x11,0x11,0x7E],//A(33)'B': [0x00,0x7F,0x49,0x49,0x49,0x3E],//B(34)'C': [0x00,0x3E,0x41,0x41,0x41,0x22],//C(35)'D': [0x00,0x7F,0x41,0x41,0x22,0x1C],//D(36)'E': [0x00,0x7F,0x49,0x49,0x49,0x41],//E(37)'F': [0x00,0x7F,0x09,0x09,0x09,0x01],//F(38)'G': [0x00,0x3E,0x41,0x49,0x49,0x7A],//G(39)'H': [0x00,0x7F,0x08,0x08,0x08,0x7F],//H(40)'I': [0x00,0x00,0x41,0x7F,0x41,0x00],//I(41)'J': [0x00,0x20,0x40,0x41,0x3F,0x01],//J(42)'K': [0x00,0x7F,0x08,0x14,0x22,0x41],//K(43)'L': [0x00,0x7F,0x40,0x40,0x40,0x40],//L(44)'M': [0x00,0x7F,0x02,0x04,0x02,0x7F],//M(45)'N': [0x00,0x7F,0x04,0x08,0x10,0x7F],//N(46)'O': [0x00,0x3E,0x41,0x41,0x41,0x3E],//O(47)'P': [0x00,0x7F,0x09,0x09,0x09,0x06],//P(48)'Q': [0x00,0x3E,0x41,0x51,0x21,0x5E],//Q(49)'R': [0x00,0x7F,0x09,0x19,0x29,0x46],//R(50)'S': [0x00,0x46,0x49,0x49,0x49,0x31],//S(51)'T': [0x00,0x01,0x01,0x7F,0x01,0x01],//T(52)'U': [0x00,0x3F,0x40,0x40,0x40,0x3F],//U(53)'V': [0x00,0x1F,0x20,0x40,0x20,0x1F],//V(54)'W': [0x00,0x3F,0x40,0x38,0x40,0x3F],//W(55)'X': [0x00,0x63,0x14,0x08,0x14,0x63],//X(56)'Y': [0x00,0x03,0x04,0x78,0x04,0x03],//Y(57)'Z': [0x00,0x61,0x51,0x49,0x45,0x43],//Z(58)'[': [0x00,0x00,0x7F,0x41,0x41,0x00],//[(59)"\\": [0x00,0x15,0x16,0x7C,0x16,0x15], //\(60)']': [0x00,0x00,0x41,0x41,0x7F,0x00],//](61)'^': [0x00,0x04,0x02,0x01,0x02,0x04],//^(62)'_': [0x00,0x40,0x40,0x40,0x40,0x40],//_(63)'`': [0x00,0x00,0x01,0x02,0x04,0x00],//`(64)'a': [0x00,0x20,0x54,0x54,0x54,0x78],//a(65)'b': [0x00,0x7F,0x48,0x44,0x44,0x38],//b(66)'c': [0x00,0x38,0x44,0x44,0x44,0x20],//c(67)'d': [0x00,0x38,0x44,0x44,0x48,0x7F],//d(68)'e': [0x00,0x38,0x54,0x54,0x54,0x18],//e(69)'f': [0x00,0x08,0x7E,0x09,0x01,0x02],//f(70)'g': [0x00,0x0C,0x52,0x52,0x52,0x3E],//g(71)'h': [0x00,0x7F,0x08,0x04,0x04,0x78],//h(72)'i': [0x00,0x00,0x44,0x7D,0x40,0x00],//i(73)'g': [0x00,0x20,0x40,0x44,0x3D,0x00],//j(74)'k': [0x00,0x7F,0x10,0x28,0x44,0x00],//k(75)'l': [0x00,0x00,0x41,0x7F,0x40,0x00],//l(76)'m': [0x00,0x7E,0x02,0x0C,0x02,0x7C],//m(77)'n': [0x00,0x7E,0x04,0x02,0x02,0x7C],//n(78)'o': [0x00,0x38,0x44,0x44,0x44,0x38],//o(79)'p': [0x00,0x7C,0x14,0x14,0x14,0x08],//p(80)'q': [0x00,0x08,0x14,0x14,0x18,0x7C],//q(81)'r': [0x00,0x7C,0x08,0x04,0x04,0x08],//r(82)'s': [0x00,0x48,0x54,0x54,0x54,0x20],//s(83)'t': [0x00,0x04,0x3F,0x44,0x40,0x20],//t(84)'u': [0x00,0x3C,0x40,0x40,0x20,0x7C],//u(85)'v': [0x00,0x1C,0x20,0x40,0x20,0x1C],//v(86)'w': [0x00,0x3C,0x40,0x30,0x40,0x3C],//w(87)'x': [0x00,0x44,0x28,0x10,0x28,0x44],//x(88)'y': [0x00,0x0C,0x50,0x50,0x50,0x3C],//y(89)'z': [0x00,0x44,0x64,0x54,0x4C,0x44],//z(90)'[': [0x00,0x00,0x08,0x36,0x41,0x00],//[(91)'|': [0x00,0x00,0x00,0x7F,0x00,0x00],//|(92)']': [0x00,0x00,0x41,0x36,0x08,0x00],//](93)'~': [0x00,0x08,0x04,0x08,0x10,0x08],//~(94)'→': [0x00,0x08,0x08,0x2A,0x1C,0x08],//→(127)'←': [0x00,0x08,0x1C,0x2A,0x08,0x08],//←(128)'↑': [0x00,0x04,0x02,0x7F,0x02,0x04],//↑(129)'↓': [0x00,0x10,0x20,0x7F,0x20,0x10]//↓(130)}module.exports = font;
显示效果图
代码实现上和之前的C写的没什么区别，就是改动下驱动代码，其他基本不变。
