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Forum Index : Microcontroller and PC projects : LCD commands
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| MOBI Guru  Joined: 02/12/2012 Location: AustraliaPosts: 819 |
For those who want to play with their LCD displays with respect to scrolling and cursors etc, here are a few codes that might help. This is for 16x2 LCD only. My 20x4 have not turned up and I haven't looked at the data sheet. Clear Display
1 Self Expanatory Cursor Home 2 Sets Cursor to Line 1 left edge Entry Mode Set 4 Cursor moves left, no shift display 5 Cursor moves left, Shift Display Left 6 Cursor moves right, No shift display 7 Cursor moves right, Shift display left Display On/Off 8 Display Off, Cursor Off, Blink Off 9 Display Off, Cursor Off, Blink On 10 Display Off, Cursor On, Blink Off 11 Display off, cursor On, Blink On 12 Display On, Cursor Off, Blink Off 13 Display on, Cursor Off, Blink On 14 Display On, Cursor On, Blink Off 15 Display On, Cursor On, Blink On Cursor Or Display Shift 16 Shift Cursor Left, Dec Address Counter 20 Shift Cursor Right, Inc Address Counter 24 Shift Display Left, Cursor Shift according to display 28 Shift Display Right, Cursor Shift according to display Function Set 32 4 Bit Mode, 5x8, 1 Line Display 36 4 Bit Mode, 5x11, 1 Line Display 40 4 Bit Mode, 5x8, 2 Line Display 44 4 Bit Mode, 5x11, 2 Line Display 48 8 Bit Mode, 5x8, 1 Line Display 52 8 Bit Mode, 5x11, 1 Line Display 56 8 Bit Mode, 5x8, 2 Line Display 60 8 Bit Mode, 5x11, 2 Line Display Set CGRAM Address 64 to 127 Set DDRAM Address 128 to 255 (128 is start of line 1 on 16x2 Display) (192 is start of line 2 on 16x2 Display) For all of the above, the RS line is low. Read Busy Flag and Address bits 0 to 6 (Bit 7 is Busy Flag) Not available as R/W pin is Connected to 0v. Write Data to CGRAM or DDRAM - may not be available as RS may not be operational. May need uMBASIC commands. David M. |
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| WhiteWizzard Guru Joined: 05/04/2013 Location: United KingdomPosts: 2817 |
I have written some code for those of you who wish to immediately directly control an LCD and hence have access to all LCD functions (i.e. blinking cursor). This is purely a temporary thing until Geoff releases any code to send LCD commands. Two subs: LcdCommand LcdData Each needs to have a 8-bit binary value passed in the form of a string. I used binary since it is easier to cross reference with values shown in data sheets which you WILL need to refer to! The following code demonstrates how to initialise an LCD and then display the word 'HI' along with the default blinking cursor. Should be a good starting point to explore further. Have fun . . . . . 
' first we need to define the Pins that the LCD are connected too - follows Geoffs built-in LCD Init function d4 = 2 d5 = 3 d6 = 4 d7 = 5 rs = 24 en = 25 'now we need to define all Pins connected to LCD as Digital Outputs SetPin(d4),dout SetPin(d5),dout SetPin(d6),dout SetPin(d7),dout SetPin(rs),dout SetPin(en),dout 'initialise LCD Pause 10 'required after initial power-up Pin(rs)=0 'rs low means instruction/command being sent Pin(en)=0 'ensure en is initially low Pin(d7) = 0 'hardcode first nibble onto Pins as per data sheet (Function Set) Pin(d6) = 0 Pin(d5) = 1 Pin(d4) = 0 GoSub LcdEn 'call this sub to load nibble into LCD LcdCommand("00101000") 'Function Set for 2 line (and 4line) LCDs - Refer to datasheet LcdCommand("00001111") 'Display On/Off Control - Refer to datasheet LcdCommand("00000110") 'Entry Mode Set - Refer to datasheet 'now write some data to LCD ('HI') LcdData("01001000") 'Write to CGRAM/DDRAM - Letter 'H' LcdData("01001001") 'Letter 'I' 'YOUR CODE CONTINUES HERE . . . . End Sub LcdCommand(arg1$) Pin(rs)=0 'rs low means value is a Command LcdWrite(arg1$) 'call common sub to write value End Sub Sub LcdData(arg1$) Pin(rs)=1 'rs high means value is data LcdWrite(arg1$) 'call common sub to write value End Sub Sub LcdWrite(arg1$) arg1$=String$(8-Len(Right$(arg1$,8)),"0")+arg1$ 'ensure binary value is length 8 - bullet proof Print arg1$ 'display binary value sent to LCD on console - useful for debugging! Pin(d7) = Val(Mid$(arg1$,1,1)) 'extract value for pin (high nibble first) Pin(d6) = Val(Mid$(arg1$,2,1)) Pin(d5) = Val(Mid$(arg1$,3,1)) Pin(d4) = Val(Mid$(arg1$,4,1)) GoSub LcdEn 'first send high nibble Pin(d7) = Val(Mid$(arg1$,5,1)) Pin(d6) = Val(Mid$(arg1$,6,1)) Pin(d5) = Val(Mid$(arg1$,7,1)) Pin(d4) = Val(Mid$(arg1$,8,1)) GoSub LcdEn 'now send low nibble End Sub LcdEn: 'sub loads value on Pins into LCD by pulsing en Pin high Pin(en) = 0 Pin(en) = 1 Pin(en) = 0 Return For everything Micromite visit micromite.org Direct Email: whitewizzard@micromite.o |
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| MOBI Guru Joined: 02/12/2012 Location: AustraliaPosts: 819 |
If you have access to an i2c based LCD, the uMite coding gets even simpler as all the data manipulation is done in the LCD i2c slave chip. This also saves you from having to define multiple uMite (or MM) pins as besides VDD and VSS, there are only two i2c lines (SCL and SDA) to plug in and these are fixed. They are also common to all other i2c devices so it is easy to create a simple bus system. The PIC based LCD Slave module I made simply receives a data byte and depending on the contents of the accompanying control byte, either treats the data byte as a character or a command. In my case, there are several control codes: 1 = treat the data byte as a character 2 = treat the data byte as a command 4 = LCD reset 8 = PWM value (0 to 255) for LCD backlight So, if we want to write "A" at The start of line 2, we first have to set the cursor position to the start of line 2 e.g. i2c write LCD_address,0,3,0,192,2 '2 means command and 192 is the cursor position
then we send the character to be displayed. i2c write LCD_address,0,3,0,65,1 '1 means character, 65 = "A"
Subsequent characters will be displayed at the next position in sequence. If for example you want to output a string of data, use a for-next loop to extract each character from the String and send it to the LCD. It will be faster than you can blink. Note that once the cursor position is set, you don't have to keep on defining the next cursor position, it happens automatically. also note that not all i2c LCDs will act the same as mine, but the source and HEX code as well as the cct diagramme are freely available to those who are game/able to programme a pic or solder on a bit of vero board. ===================== bottom note on command table re RS was not meant to be included in the first post. RS high and RW low writes the character to the display at the current cursor position. David M. |
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