NHD - 0420DZ - FL - YBW - 33V3字符液晶显示模块详解

在电子设备日益智能化的今天，液晶显示模块作为人机交互的重要窗口，其性能和特性对于设备的整体表现起着关键作用。今天我们就来深入探讨一下NHD - 0420DZ - FL - YBW - 33V3字符液晶显示模块，为各位电子工程师在设计过程中提供参考。

文件下载：NHD-0420DZ-FL-YBW-33V3.pdf

1. 产品概述

NHD - 0420DZ - FL - YBW - 33V3是Newhaven Display International, Inc.推出的一款字符液晶显示模块。它具有4行20字符的显示能力，内置ST7066U控制器，采用+3.3V电源供电，具备1/16 duty、1/4 bias的特点，并且符合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。
• “DZ”：为具体型号。
• “F”：表示半透反射型。
• “L”：采用黄/绿色LED背光。
• “Y - B”：STN正性，黄/绿色6:00最佳视角。
• “W”：宽温度范围。
• “33V3”：表示3.3V的VDD和3.0V的LED供电。

2. 引脚说明与接线图

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	Four low order bi - directional three - state data bus lines. These four are 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 (300 mA @ 3.0V)
16	LED -	Power Supply	Backlight Cathode (Ground)

推荐的LCD连接器为2.54mm间距引脚，不过文档中未提及背光连接器的具体配对信息。各位工程师在实际设计中，要根据引脚功能准确接线，避免因接线错误导致模块无法正常工作。

3. 电气与光学特性

3.1 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	-	200	300	400	mA
Backlight Supply Voltage	VLED	ILED = 300 mA	2.8	3.0	3.2	V

需要注意的是，背光的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电流在最大允许值以下。

3.2 光学特性

Item			Symbol	Condition	Min.	Typ.	Max.	Unit
Optimal Viewing Angles	Top		ϕY+	CR ≥ 2	30	40	-	°
Bottom		ϕY -	50	60	-	°
Left		θX -	50	60	-	°
Right			θX+	50	60	-	°
Contrast Ratio			CR	-	2	5	-	-
		Rise	TR	TOP = 25°C	-	150	250	ms
Response Time		Fall	TF	-	200	300	ms

了解这些光学特性有助于我们在实际应用中调整显示效果，以达到最佳的视觉体验。大家在设计时，是否考虑过如何根据这些特性优化显示效果呢？

4. 控制器信息与DDRAM地址

该模块内置ST7066U控制器，其详细规格可从http://www.newhavendisplay.com/app_notes/ST7066U.pdf下载。DDRAM地址有特定的分布规律，工程师们在进行数据读写操作时，要依据这个地址分布来准确操作，确保数据正确显示。

5. 指令表

模块提供了一系列指令，用于控制显示内容、光标位置等。例如：	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

熟悉这些指令的功能和执行时间，能让我们更好地控制显示模块的行为。在实际编程中，大家是否遇到过指令执行异常的情况呢？

6. 时序特性

6.1 从MPU向ST7066U写数据

Tc	Enable Cycle Time	Pin E	1200			ns
TPW	Enable Pulse Width	Pin E	140			ns
TR,TF	Enable Rise/Fall Time	Pin E			25	ns
TAS	Address Setup Time	Pins: RS,RW,E	0	0		ns
TAH	Address Hold Time	Pins: RS,RW,E	10	-		ns
TDSW	Data Setup Time	Pins: DB0 - DB7	40	-		ns
TH	Data Hold Time	Pins: DB0 - DB7	10			ns

6.2 从ST7066U向MPU读数据

Tc	Enable Cycle Time	Pin E	1200		-	ns
TPW	Enable Pulse Width	Pin E	140			ns
TR,TF	Enable Rise/Fall Time	Pin E		-	25	ns
TAS	Address Setup Time	Pins: RS,RW,E	0	0		ns
TAH	Address Hold Time	Pins: RS,RW,E	10			ns
TDDR	Data Setup Time	Pins: DB0 - DB7	-		100	ns
TH	Data Hold Time	Pins: DB0 - DB7	10			ns

在设计电路和编写代码时，要严格按照这些时序要求进行操作，否则可能会导致数据传输错误。

7. 初始化程序

文档提供了8位和4位两种初始化方式：

7.1 8位初始化

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

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

void init() {
    E = 0; 
    Delay(100); //Wait >40 msec after power is applied 
    command(0x30);
    command(0x30); //command 0x30 = Wake up 
    Delay(30);
    command(0x30);
    command(0x30); //command 0x30 = Wake up #2 
    Delay(10);
    command(0x30);
    command(0x30); //command 0x30 = Wake up #3 
    Delay(10);
    command(0x38);
    command(0x38); //Function set: 8 - bit/2 - line 
    command(0x0c); //Display ON; Cursor ON 
    command(0x06); //Entry mode set 
}

7.2 4位初始化

void command(char i) {
    P1 = i;
    D_I = 0; //D/I = LOW : send instruction 
    R_W = 0; 
    Nybble(); //Send upper 4 bits 
    i = i < < 4; //Shift over by 4 bits 
    P1 = i;
    Nybble(); //Send upper 4 bits 
} 

void write(char i) {
    P1 = i;
    D_I = 1; //D/I = HIGH : send data 
    R_W = 0; 
    Nybble(); //Clock upper 4 bits 
    i = i < < 4; //Shift over by 4 bits 
    P1 = i;
    Nybble(); //Clock upper 4 bits 
} 

void Nybble() {
    E = 1; 
    Delay(1);
    E = 0; //Clock enable: falling edge 
} 

void init() {
    P1 = 0; P3 = 0; 
    Delay(100); //Wait >40 msec after power is applied 
    P1 = 0x30;
    Delay(30);
    Nybble(); //command 0x30 = Wake up 
    Delay(10);
    Nybble(); //command 0x30 = Wake up #2 
    Delay(10);
    Nybble(); //command 0x30 = Wake up #3 
    Delay(10);
    P1 = 0x20;
    Nybble(); //Function set: 4 - bit interface 
    command(0x28); //Function set: 4 - bit/2 - line 
    command(0x0F); //Display ON; Blinking cursor 
    command(0x06); //Entry Mode set 
}

工程师们可以根据实际需求选择合适的初始化方式，在使用这些代码时，要注意延时函数的具体实现，确保初始化过程正确。

8. 质量信息与使用注意事项

8.1 质量测试

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

8.2 使用注意事项

使用LCD/LCM时的详细注意事项可参考http://www.newhavendisplay.com/specs/precautions.pdf，保修信息和条款可查看http://www.newhavendisplay.com/index.php?main_page=terms。在实际应用中，我们要充分考虑这些测试结果和注意事项，确保模块在各种环境下都能稳定可靠地工作。

总之，NHD - 0420DZ - FL - YBW - 33V3字符液晶显示模块具有丰富的功能和良好的性能。电子工程师们在设计过程中，要全面了解其各项特性，合理运用相关指令和初始化程序，才能充分发挥该模块的优势，为产品带来更好的显示效果。大家在使用这款模块时，还有哪些疑问或者经验可以分享呢？欢迎在评论区交流。