Want your Arduino projects to display status messages or sensor readings? Then these LCD displays might be the perfect fit. They are extremely common and a fast way to add a readable interface to your project. This tutorial will cover everything you need to know to get up and running with Character LCDs. It is basically a display unit which uses liquid crystals to produce a visible image. When current is applied to this special kind of crystal, it turns opaque blocking the backlight that lives behind the screen.
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The A is a 16 character, 2 line display that is similar to many other 16x2 displays in use today. These pixels should be controlled correctly so that we can display the desired characters. The pinout for these LCD modules is usually as shown in Figure 1 below. The VEE pin is used to adjust the display contrast. Although we can both write and read from the data bus, a write operation is more common. The definition of the different parameters and the expected values are given in Table 1.
Then, the E signal should have a high-to-low edge which starts a write operation. Note that t DSW before this edge the data must be valid. Besides, after the falling edge of E, the control signals and the data should not change for some time denoted by t AH and t H in the figure. This shows that we should wait for some time before starting to do the next read or write operation. To summarize, a high-to-low transition on E starts data read or write but there are certain timing conditions that must be met.
This instruction clears the display. What does this mean? However, only some of these 80 characters are displayed on the LCD. According to Figure 4, if we write a particular character to the DDRAM address 0x00, it will be displayed in the first cell of the upper line.
Similarly, if we write a character to address 0x40, that will appear in the first cell of the lower line. Moreover, the AC determines the position on the LCD that a character entered by a write operation goes to. Note that LCDs support shift operations that can change the relationships that were shown in Figure 4. For example, a left shift applied to the default status of Figure 4 will lead to Figure 5.
For more information, please refer to the datasheet. This command also brings the cursor back to the home position and returns the display to its original status if it was shifted. When S is 0, the display does not shift. In many cases, we want the cursor position to increment after a write operation while the display remains still the shift option is not utilized. For such applications, the command code for DB7-DB0 will be the hexadecimal value 0x By setting the D bit to 1 or 0, we can respectively turn the display on and off.
B controls the blinking capability of the cursor position. The N bit specifies the number of display lines. For a single line display, N should be 0. For two lines and more, N should be 1. It can be used to write a character in a particular cell of the LCD. For example, sending the hexadecimal value 0x80 to the data bus will make the cursor to move to the first cell of the upper row.
The following table summarizes the commands discussed above. We need two functions to write commands and data to the LCD module. In this way, we can easily modify the constants to adapt the code for a future project that uses a different pin connection. We can send instructions to the LCD using the following function:. We need to give the LCD some time to finish its current job if there is any. Similarly, we can write a function to send a character to the LCD:. The following function initializes the LCD by sending some commands from Table 2.
Using these functions we can have the basic functionality of the LCD module. The following code shows the main function of an example:. The output of the above code compiled and simulated using CodeVision and Proteus tools is shown in Figure In fact, I have used the above functions with even faster bit MCUs but if you run into any trouble, you can introduce a small delay in the appropriate lines of the code to make sure that the timing requirements are met.
The example C code given in the article can be adjusted to be used with MCUs from other vendors. To see a complete list of my articles, please visit this page.
Please advise. Copying and pasting this code directly into AVR Studio 7 requires minor changes to the code. Instructions can be found here : 1. Anywhere there is reference to the const unsigned chars replace with the shift operations.
You can then comment out the const unsigned chars. The leading underscore is to signify internal library use, i. Don't have an AAC account? Create one now. Forgot your password? Click here. Latest Projects Education. The Module Pinout The A is a 16 character, 2 line display that is similar to many other 16x2 displays in use today. Figure 1. Image courtesy of AAC. The Timing Diagram for a Write Operation Although we can both write and read from the data bus, a write operation is more common.
Figure 2. Timing diagram of a write operation. Clear Display This instruction clears the display. Figure 3. Figure 4. Return Home Figure 6 gives the code for this command and its description. Figure 6. Entry Mode Set The details of this command are given in Figure 7. Figure 7. Figure 8. Figure 9. Figure Learn More About: mcu lcd display hd lcd drivercontroller avr microcontroller.
You May Also Like. Log in to comment. Nicholas Jacobs June 06, Nicholas Jacobs June 12, Great tutorial, it provides just enough information to make me curious. I bit-twiddled bit shifting instead of bit masking. Sign In Stay logged in Or sign in with. Continue to site.
Interfacing 16×2 Character LCD Module with Arduino
This tutorial includes everything you need to know about controlling a character LCD with Arduino. I have included a wiring diagram and many example codes. These displays are great for displaying sensor data or text and they are also fairly cheap. The first part of this article covers the basics of displaying text and numbers. As you will see, you need quite a lot of connections to control these displays. I therefore like to use them with an I2C interface module mounted on the back.
How to Interface a 16×2 LCD Module with an MCU
Pin description is shown in the table below. Its extended capacity is 80 X 8 bits, or 80 characters. The character generator ROM generates 5 x 8 dot or 5 x 10 dot character patterns from 8-bit character codes see Figure 5 and Figure 6 for more details. It can generate 5 x 8 dot character patterns and 32 5 x 10 dot character patterns. Userdefined character patterns are also available by mask-programmed ROM.