Commands and Instruction set

Only the instruction register (IR) and the data register (DR) of the LCD can be controlled by the MCU. Before starting the internal operation of the LCD, control information is temporarily stored into these registers to allow interfacing with various MCUs, which operate at different speeds, or various peripheral control devices. The internal operation of the LCD is determined by signals sent from the MCU. These signals, which include register selection signal (RS), read/write signal (R/W), and the data bus (DB0 to DB7), make up the LCD instructions (Table 3). There are four categories of instructions that:


  • Designate LCD functions, such as display format, data length, etc.
  • Set internal RAM addresses
  • Perform data transfer with internal RAM
  • Perform miscellaneous functions



Table 3: Command and Instruction set for LCD type HD44780


Although looking at the table you can make your own commands and test them. Below is a breif list of useful commands which are used frequently while working on the LCD.


No. Instruction Hex Decimal
1Function Set: 8-bit, 1 Line, 5x7 Dots0x3048
2Function Set: 8-bit, 2 Line, 5x7 Dots0x3856
3Function Set: 4-bit, 1 Line, 5x7 Dots0x2032
4Function Set: 4-bit, 2 Line, 5x7 Dots0x2840
5Entry Mode0x066
6Display off Cursor off
(clearing display without clearing DDRAM content)
0x088
7Display on Cursor on0x0E14
8Display on Cursor off0x0C12
9Display on Cursor blinking0x0F15
10Shift entire display left0x1824
11Shift entire display right0x1C30
12Move cursor left by one character0x1016
13Move cursor right by one character0x1420
14Clear Display (also clear DDRAM content)0x011
15Set DDRAM address or coursor position on display0x80 + address*128 + address*
16Set CGRAM address or set pointer to CGRAM location0x40 + address**64 + address**
Table 4: Frequently used commands and instructions for LCD
* DDRAM address given in LCD basics section see Figure 2,3,4
** CGRAM address from 0x00 to 0x3F, 0x00 to 0x07 for char1 and so on..

The table above will help you while writing programs for LCD. But after you are done testing with the table 4, i recommend you to use table 3 to get more grip on working with LCD and trying your own commands. In the next section of the tutorial we will see the initialization with some of the coding examples in C as well as assembly.

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ExperimenterUK
Mon Dec 03 2018, 05:17 PM
Please post questions in the forum. The chat box is for chat
Mon Dec 03 2018, 06:43 AM
help!me!
help! I don't understand busy flag!
Sun Dec 02 2018, 08:01 PM
ile
hello
Mon Nov 12 2018, 05:58 AM
Pavan_user
i have seen your replica of I2C programming using AT89C51 but i am unable to understand the "ack_bit" variable usage ...looks like it is always 1...can you elaborate how acknowledgment is working....
bgk3678
Tue Nov 06 2018, 02:36 PM
kindly any one give solution for my problem
ExperimenterUK
Mon Nov 05 2018, 09:48 PM
Pins high is the normal state. You need a program to set them low
mayengbam
Sun Nov 04 2018, 05:41 PM
hello, i am niranjoy, alll the port of my 8051 is always high, even i erase all the program. why is it so happen and what is the problem. any one please help me!
Sun Nov 04 2018, 02:16 PM
BASAVARAJ g kudamble
hi I am interfacing GSM 300 to 8051 microcontroller to receive message from mobile
ExperimenterUK
Sat Sep 29 2018, 06:28 PM
Please post questions in the forum.
Sat Sep 29 2018, 11:26 AM
Ashfaq Ch
hi i have some AT89C51RC microcontrollers already programed. some one help us to how to download from AT89C51RC and after study and edit all corractions reload to AT89C51RC controller

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