探索NHD - 0420AZ - FL - GBW - 33V3字符液晶显示模块

在电子设计领域，液晶显示模块是不可或缺的组件，它为设备提供了直观的信息展示界面。今天，我们将深入探讨Newhaven Display International公司的NHD - 0420AZ - FL - GBW - 33V3字符液晶显示模块，了解其特性、参数以及使用方法。

文件下载：NHD-0420AZ-FL-GBW-33V3.pdf

一、模块概述

NHD - 0420AZ - FL - GBW - 33V3是一款4行20字符的液晶显示模块，内置ST7066U或等效控制器，采用3.3V电源供电，符合RoHS标准。其型号各部分含义如下：

• “NHD - ”：代表Newhaven Display。
• “0420 - ”：表示4行20字符。
• “AZ - ”：为具体型号。
• “F - ”：表示半透反射型。
• “L - ”：采用边缘黄/绿色LED背光源。
• “G - ”：STN正性灰色。
• “B - ”：6:00最佳视角。
• “W - ”：宽温度范围。
• “33V3 - ”：3.3V逻辑电源，3.0V背光源电源。

二、机械与电气特性

1. 机械绘图

模块的机械绘图信息属于Newhaven Display International公司的专有财产，未经许可不得复制、再现和披露。

2. 引脚说明

Pin No.	Symbol	External Connection	Function Description
1	VSS	Power Supply	Ground
2	VDD	Power Supply	Supply Voltage for Logic (+3.3V)
3	V0	Power Supply	Supply Voltage for Contrast (approx. 0V)
4	RS	MPU	Register Select signal. RS = 0: Command, RS = 1: Data
5	R/W	MPU	Read/Write select signal, R/W = 1: Read R/W = 0: Write
6	E	MPU	Operation Enable signal. Falling edge triggered.
7 - 10	DB0 - DB3	MPU	For low order bi - directional three - state data bus lines. Not used during 4 - bit operation.
11 - 14	DB4 - DB7	MPU	Four high order bi - directional three - state data bus lines.
15	LED+	Power Supply	Backlight Anode (15mA @ 3V)
16	LED -	Power Supply	Backlight Cathode (Ground)

推荐使用2.54mm间距的引脚作为LCD连接器。

3. 电气特性

Item	Symbol	Condition	Min.	Typ.	Max.	Unit
Operating Temperature Range	TOP	Absolute Max	- 20	-	+70	⁰C
Storage Temperature Range	TST	Absolute Max	- 30	-	+80	⁰C
Supply Voltage	VDD	-	3.1	3.3	3.5	V
Supply Current	IDD	VDD = 3.3V	0.5	1.5	3.0	mA
Supply for LCD (contrast)	VLCD	TOP = 25°C	3.1	3.3	3.5	V
“H” Level input	VIH	-	0.7 * VDD	-	VDD	V
“L” Level input	VIL	-	VSS	-	0.6	V
“H” Level output	VOH	-	0.75 * VDD	-	VDD	V
“L” Level output	VOL	-	VSS	-	0.2 * VDD	V
Backlight Supply Current	ILED	-	-	15	20	mA
Backlight Supply Voltage	VLED	ILED = 15mA	2.8	3.0	3.3	V

需要注意的是，背光源的LED由电流驱动，驱动电压仅作参考，必须选择合适的驱动电压以确保背光源电流低于最大额定值。

三、光学特性

Item			Symbol	Condition	Min.	Typ.	Max.	Unit
Optimal Viewing Angles	Top		ϕY+	CR ≥ 2	-	40	-	°
Bottom		ϕY -	-	60	-	°
Left		θX -	-	60	-	°
Right			θX+	-	60	-	°
Contrast Ratio			CR	-	2	5	-	-
Response Time	Rise		TR	TOP = 25°C	-	150	250	ms
	Fall		TF	-	200	300	ms

这些光学特性决定了模块在不同视角和环境下的显示效果，工程师在设计时需要根据实际应用场景进行考虑。

四、控制器信息

模块内置ST7066U控制器，可从http://www.newhavendisplay.com/app_notes/ST7066U.pdf下载其详细规格。DDRAM地址分配如下：	1	2	3	4	5	6	7	8	9	10	11		12 13	14
					00 01 02 03 04 05 06		07 08		09			0A 0B 0C 0D 0E 0F 10 11 12 13
					40 41 42 43 44 45 46		47 48		49			4A 4B 4C 4D 4E 4F 50 51 52 53
										14 15 16 17 18 19 1A 1B 1C 1D 1E	1F	20	21

五、命令表

模块提供了一系列命令，用于控制显示、设置模式等操作。以下是部分常见命令：	Instruction	Instruction code										Description	270 KHZ Execution time (fosc =
RS									R/W DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0
Clear Display	0	0	0	0	0	0	0	0	0	1	Write “20H” to DDRAM and set DDRAM address to “00H” from AC	1.52ms
Return Home	0	0	0	0	0	0	0	0	1	-	Set DDRAM Address to “00H” from AC and return cursor to its original position if shifted. The contents of DDRAM are not changed.	1.52ms
Entry mode Set	0	0	0	0	0	0	0	1	I/D	SH	Sets cursor move direction and specifies display shift. These parameters are performed during data write and read.	37µs
Display ON/ OFF control	0	0	0	0	0	0	1	D	C	B	D = 1: Entire display on C = 1: Cursor on B = 1: Blinking cursor on	37µs

工程师可以根据需要选择合适的命令来实现不同的显示效果。

六、时序特性

1. 从MPU向ST7066U写数据

	Enable Cycle Time	Pin E				ns
TR,TF		Pin E			25
TAS	Address Setup Time	Pins: RS,RW,E
	Address Hold Time	Pins: RS,RW,E		-
	Data Setup Time		80			ns
		Pins: DB0 - DB7	10

2. 从ST7066U向MPU读数据

Tc		Pin E				ns
TPW	Enable Pulse Width	Pin E	480
TR,TF		Pin E		-	25	ns
TAS			0	-		ns
TAH		Pins: RS,RW,E	10			ns
TDDR	Data Setup Time	Pins: DB0 - DB7			320
			10			ns

了解这些时序特性对于正确读写数据至关重要，在设计电路时需要严格按照这些参数进行设置。

七、初始化程序

1. 8位初始化

void command(char i) 
{
    P1 = i; //put data on output Port
    D_I = 0;
    D_I = 0; //D/I = LOW : send instruction 
    R_W = 0; E = 1; //R/W = LOW:Write
    Delay (1);
    Delay(1); //enable pulse width >= 300ns 
    E = 0; //Clock enable:falling edge
} 

void write(char i) 
{
    P1 = i; D_I = 1; R_W = 0; //put data on output Port //D/I = HIGH : send data //R/W = LOW:Write
    E = 1; 
    Delay (1);
    Delay(1); //enable pulse width >= 300ns 
    E = 0; //Clock enable:falling edge
} 

void init() 
{
    E = 0; 
    Delay(100); //Wait >40 msec after power is applied 
    Delay (100);
    command (0x30); //command 0x30 = Wake up
    Delay (30);
    Delay(30); //must wait 5ms, busy flag not available 
    command (0x30); //command 0x30 = Wake up #2
    Delay (10);
    Delay(10); //must wait 160us, busy flag not available 
    command(0x30); //command 0x30 = Wake up #3 
    command (0x30);
    Delay(10); //must wait 160us, busy flag not available 
    Delay (10);
    command (0x38);
    command(0x38); //Function set: 8 - bit/2 - line 
    command (0x10); //Set cursor
    command (0x0c);
    command(0x0c); //Display ON; Cursor ON 
    command (0x06); //Entry mode set
}

2. 4位初始化

void command(char i) 
{
    P1 = i; //put data on output Port
    D_I = 0;
    D_I = 0; //D/I = LOW : send instruction 
    R_W = 0; Nybble(); i = i < < 4; //R/W = LOW:Write //Send lower 4 bits //Shift over by 4 bits
    P1 = i;
    P1 = i; //put data on output Port 
    Nybble(); //Send upper 4 bits
}

void write(char i) 
{ 
    P1 = i; //put data on output Port 
    P1 = i;
    R_W = 0; Nybble(); i = i < < 4; P1 = i; D_I = 1; //D/I = HIGH : send data //R/W = LOW: Write //Clock lower 4 bits //Shift over by 4 bits
    P1 = i; //put data on output Port 
    Nybble (); //Clock upper 4 bits
}

void Nybble() 
{
    E = 1; 
    Delay (1);
    Delay(1); //enable pulse width >= 300ns 
    E = 0; //Clock enable:falling edge
}

void init() 
{
    P1 = 0; P3 = 0; 
    Delay (100);
    Delay(100); //Wait >40 msec after power is applied 
    P1 = 0x30; //put 0x30 on the output port 
    P1 = 0x30;
    Delay (30);
    Delay(30); //must wait 5ms, busy flag not available 
    Nybble(); //command 0x30 = Wake up
    Delay (10);
    Delay(10); //must wait 160us, busy flag not available 
    Nybble(); //command 0x30 = Wake up #2
    Delay (10);
    Delay(10); //must wait 160us, busy flag not available 
    Nybble ();
    Nybble(); //command 0x30 = Wake up #3 
    Delay(10); //can check busy flag now instead of delay 
    Delay (10);
    P1 = 0x20; //put 0x20 on the output port 
    P1 = 0x20;
    Nybble(); //Function set: 4 - bit interface 
    Nybble ();
    command (0x28);
    command(0x28); //Function set: 4 - bit/2 - line 
    command (0x10); //Set cursor
    command (0x0F);
    command(0x0F); //Display ON; Blinking cursor 
    command (0x06); //Entry Mode set
}

八、质量与使用注意事项

1. 质量测试

模块经过了多项质量测试，包括高温存储、低温存储、高温操作、低温操作、高温高湿操作、热冲击抗性、振动测试和静电测试等。测试条件和注意事项如下：	Test Item	Content of Test	Test Condition	Note
High Temperature storage	Endurance test applying the high storage temperature for a long time.	+80⁰C , 48hrs	2
Low Temperature storage	Endurance test applying the low storage temperature for a long time.	-30⁰C , 48hrs	1,2
High Temperature Operation	Endurance test applying the electric stress (voltage & current) and the high thermal stress for a long time.	+70⁰C 48hrs	2
Low Temperature Operation	Endurance test applying the electric stress (voltage & current) and the low thermal stress for a long time.	-20⁰C , 48hrs	1,2
High Temperature / Humidity Operation	Endurance test applying the electric stress (voltage & current) and the high thermal with high humidity stress for a long time.	+40⁰C , 90% RH , 48hrs	1,2
Thermal Shock resistance	Endurance test applying the electric stress (voltage & current) during a cycle of low and high thermal stress.	0⁰C,30min -> 25⁰C,5min -> 50⁰C,30min = 1 cycle 10 cycles
Vibration test	Endurance test applying vibration to simulate transportation and use.	10 - 55Hz , 15mm amplitude. 60 sec in each of 3 directions X,Y,Z For 15 minutes	3
Static electricity test	Endurance test applying electric static discharge.	VS = 800V, RS = 1.5kΩ, CS = 100pF One time