HELP for 128x64 graphical lcd
This site is of great help(both for graphical and character LCD):
Website
Also the following information might be helpful for you to get started for the first time with a graphical LCD(128 x 64):
Industry-Standard Graphical LCD Display Info:
To call this LCD the "industry standard" might be a little bit questionable,
but most small LCD displays do use this standard. It seems that just as the
Hitachi HD44780 is the clear leader in controlling character-based LCDs, the
Samsung KS0108 is the most popular chip for controlling graphical LCDs, and
most LCD manufacturers simply follow the KS0108 standard for smaller
graphical LCDs (in the 128 x 64 pixel or 256 x 64 pixel configuration).
Typical pinout is as follows:
1: Vss (Ground)
2: Vdd (+5V)
3: V0 (Contrast adjust)
4: RS (or D/I) (0 = instruction, 1 = data)
5: R/W (0 = Write to LCD, 1 = read from LCD)
6: E (Enable)
7: DB0
8: DB1
9: DB2
10: DB3
11: DB4
12: DB5
13: DB6
14: DB7
15: CS1 (Chip select 1; Selects left side of screen)
16: CS2 (Chip select 2; Selects right side of screen)
17: RST (Reset; Active-low)
18: Vee (-8V OUTPUT)
19: A (Backlight anode) (Positive connection)
20: K (Backlight cathode) (Negative connection)
Vss is Ground, and Vdd is +5V. So far, everything seems to be the usual
story. But the other two "V" pins have a bit of a surprise in store.
On an LCD based on the KS0108, the pin named Vee is misleading. After using a
character-based LCD and feeding a negative voltage into it to adjust the LCD
contrast, you might naturally assume that you're supposed to do the same
here. But things are totally different with the KS0108: Vee is not an input,
it's an output! It produces about -8 volts all by itself (although mine seems
to produce more like -15 volts). The LCD contrast adjust pin here is actually
V0. Typically, a potentiometer is used to control V0. Normally the two sides
of the pot are connected between Vee and Vdd, and the pot's "wiper" (center
connection) is then connected to V0. I recommend the use of a small trimmer
resistor in the range of 5K to 20K, which you can then fine-tune with a
screwdriver. Once you understand it, this is supposed to be easier to
implement, because instead of needing two separate voltage supplies, you only
need one, and the board itself creates its own negative voltage for you.
The CS pins essentially divide the display into 64 x 64 pixel blocks. The
pinout here is for a 128 x 64 LCD; CS1 turns the left side on and off, and
CS2 controls the right side. This is because each KS0108 chip is only capable
of handling 64 columns, so there are actually two chip controllers on such an
LCD, each controlling one half of the display. On 256 x 64 LCDs, there would
be two additional CS pins. CS1 would be the leftmost quarter of the screen,
and CS4 would be the rightmost. (The CS pins may be active-low on some
modules.)
The reset pin is an active-low reset signal. It does not seem to actually
need to be used when you power up the display. All other pins are duplicates
of what you'd see on a standard HD44780 character-based display.
If your LCD has an additional two pins for the backlight, one is the positive
end and one is the negative (ground) end. Typically, these backlights will
operate on about 5 volts as well, but usually they use slightly less; In
fact, some backlights have a maximum voltage rating of no more than 4.5
volts, and some may even be 3.5 volts. Beware of this, and think twice about
connecting the backlight directly to a 5-volt supply. You should also use a
resistor (at least 100 to 200 ohms) with the backlight to provide overload
protection.
Quick-Start For Industry-Standard Graphical LCD Displays:
Begin by hooking up ground to Vss and 5 volts to Vdd. Put a 20K potentiometer
between Vee and Vdd, and connect the pot's wiper (center connection) to V0.
At this time, you may wish to pause and actually power on the LCD as it is so
you can adjust the contrast to an appropriate setting. Or, you can save this
for later; It's your choice.
Let's begin by turning the display on. The command for this is 00111111, so
put that on the data bus (DB7 and DB6 low, the other 6 high). Set both RS and
R/W low (because this is to be written to the instruction register). Also
make sure at least one of the two CS pins are active, because otherwise the
instruction will have no effect.
Now pulse the Enable pin, and the display should come on. You may not be able
to see anything on it yet; It's often the case that when a graphical LCD
display is first powered on, there will be some garbage stored in the DDRAM
as random noise, and this may pop up on the screen.
Now set RS high, so the data you write to the LCD will be displayed on the
screen. Now you can put anything you want on the data bus, and then pulse the
Enable pin; The contents of the data bus should start showing up on the
screen. Remember that each pin on the data bus is one pixel at the current
memory address.
You can also experiment with changing the current memory address. To change
the horizontal position, use the 01YYYYYY command, where YYYYYY is the binary
number of the horizontal position you wish to use, from 0 to 63. Remember,
each chip on the LCD module controls only 64 columns. If you wanted to
control column 70, therefore, you would turn on CS2 and then use the 01000110
command, because that would be the sixth column from the beginning of the
second chip's area, and 64 + 6 = 70.
Changing the vertical position is just as easy: Use the 10111XXX command,
where XXX is the "page" you want to move to. The rows on the display are
divided into 8 pages, each of which is 8 pixels high. This is because each
byte in the DDRAM is actually 8 pixels (one pixel for each bit).
Now you know most of the commands for the KS0108, and you can begin to
interface it to a 16C84 or 16F84 PIC (a popular electronics project), or even
a full-blown computer CPU like a Z80 or 6502. Have fun.
Website
Also the following information might be helpful for you to get started for the first time with a graphical LCD(128 x 64):
Industry-Standard Graphical LCD Display Info:
To call this LCD the "industry standard" might be a little bit questionable,
but most small LCD displays do use this standard. It seems that just as the
Hitachi HD44780 is the clear leader in controlling character-based LCDs, the
Samsung KS0108 is the most popular chip for controlling graphical LCDs, and
most LCD manufacturers simply follow the KS0108 standard for smaller
graphical LCDs (in the 128 x 64 pixel or 256 x 64 pixel configuration).
Typical pinout is as follows:
1: Vss (Ground)
2: Vdd (+5V)
3: V0 (Contrast adjust)
4: RS (or D/I) (0 = instruction, 1 = data)
5: R/W (0 = Write to LCD, 1 = read from LCD)
6: E (Enable)
7: DB0
8: DB1
9: DB2
10: DB3
11: DB4
12: DB5
13: DB6
14: DB7
15: CS1 (Chip select 1; Selects left side of screen)
16: CS2 (Chip select 2; Selects right side of screen)
17: RST (Reset; Active-low)
18: Vee (-8V OUTPUT)
19: A (Backlight anode) (Positive connection)
20: K (Backlight cathode) (Negative connection)
Vss is Ground, and Vdd is +5V. So far, everything seems to be the usual
story. But the other two "V" pins have a bit of a surprise in store.
On an LCD based on the KS0108, the pin named Vee is misleading. After using a
character-based LCD and feeding a negative voltage into it to adjust the LCD
contrast, you might naturally assume that you're supposed to do the same
here. But things are totally different with the KS0108: Vee is not an input,
it's an output! It produces about -8 volts all by itself (although mine seems
to produce more like -15 volts). The LCD contrast adjust pin here is actually
V0. Typically, a potentiometer is used to control V0. Normally the two sides
of the pot are connected between Vee and Vdd, and the pot's "wiper" (center
connection) is then connected to V0. I recommend the use of a small trimmer
resistor in the range of 5K to 20K, which you can then fine-tune with a
screwdriver. Once you understand it, this is supposed to be easier to
implement, because instead of needing two separate voltage supplies, you only
need one, and the board itself creates its own negative voltage for you.
The CS pins essentially divide the display into 64 x 64 pixel blocks. The
pinout here is for a 128 x 64 LCD; CS1 turns the left side on and off, and
CS2 controls the right side. This is because each KS0108 chip is only capable
of handling 64 columns, so there are actually two chip controllers on such an
LCD, each controlling one half of the display. On 256 x 64 LCDs, there would
be two additional CS pins. CS1 would be the leftmost quarter of the screen,
and CS4 would be the rightmost. (The CS pins may be active-low on some
modules.)
The reset pin is an active-low reset signal. It does not seem to actually
need to be used when you power up the display. All other pins are duplicates
of what you'd see on a standard HD44780 character-based display.
If your LCD has an additional two pins for the backlight, one is the positive
end and one is the negative (ground) end. Typically, these backlights will
operate on about 5 volts as well, but usually they use slightly less; In
fact, some backlights have a maximum voltage rating of no more than 4.5
volts, and some may even be 3.5 volts. Beware of this, and think twice about
connecting the backlight directly to a 5-volt supply. You should also use a
resistor (at least 100 to 200 ohms) with the backlight to provide overload
protection.
Quick-Start For Industry-Standard Graphical LCD Displays:
Begin by hooking up ground to Vss and 5 volts to Vdd. Put a 20K potentiometer
between Vee and Vdd, and connect the pot's wiper (center connection) to V0.
At this time, you may wish to pause and actually power on the LCD as it is so
you can adjust the contrast to an appropriate setting. Or, you can save this
for later; It's your choice.
Let's begin by turning the display on. The command for this is 00111111, so
put that on the data bus (DB7 and DB6 low, the other 6 high). Set both RS and
R/W low (because this is to be written to the instruction register). Also
make sure at least one of the two CS pins are active, because otherwise the
instruction will have no effect.
Now pulse the Enable pin, and the display should come on. You may not be able
to see anything on it yet; It's often the case that when a graphical LCD
display is first powered on, there will be some garbage stored in the DDRAM
as random noise, and this may pop up on the screen.
Now set RS high, so the data you write to the LCD will be displayed on the
screen. Now you can put anything you want on the data bus, and then pulse the
Enable pin; The contents of the data bus should start showing up on the
screen. Remember that each pin on the data bus is one pixel at the current
memory address.
You can also experiment with changing the current memory address. To change
the horizontal position, use the 01YYYYYY command, where YYYYYY is the binary
number of the horizontal position you wish to use, from 0 to 63. Remember,
each chip on the LCD module controls only 64 columns. If you wanted to
control column 70, therefore, you would turn on CS2 and then use the 01000110
command, because that would be the sixth column from the beginning of the
second chip's area, and 64 + 6 = 70.
Changing the vertical position is just as easy: Use the 10111XXX command,
where XXX is the "page" you want to move to. The rows on the display are
divided into 8 pages, each of which is 8 pixels high. This is because each
byte in the DDRAM is actually 8 pixels (one pixel for each bit).
Now you know most of the commands for the KS0108, and you can begin to
interface it to a 16C84 or 16F84 PIC (a popular electronics project), or even
a full-blown computer CPU like a Z80 or 6502. Have fun.
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