Datasheet

Memory LCD Programming
2 LCD Application Note
LCD COMMANDS
There are four commands that can be sent to a
memory LCD panel:
• Write line
• Write multiple lines
• Change VCOM
•Clear screen
The commands are explained below. The illustra-
tions are in little-endian format with the LSB on the left
and the MSB on the right.
Data Structure
Data is sent to the panel in little-endian format; with
the LSB first. The data width for the Write Line and
Write Multiple Line commands depends on the horizon-
tal resolution of the panel itself. Therefore, if you’re
working with a panel having a resolution of 400 × 240,
then the data width for this panel will require a minimum
of 400 bits of data (plus overhead).
Write Line
The minimum amount of data that can be written to
the panel with the Write Line comand is one line. The
actual width of the data written depends on the horizon-
tal resolution of the panel itself. Therefore, a panel with
a resolution of 400 × 240 will require a minimum of 400
bits of data (plus overhead). See Figure 3.
The command structure for Write Line is as follows:
• Command: 8 bits (including V-bit)
• Line address: 8 bits
• Data bits: leftmost pixel first, little-endian format, with
data width depending on the resolution of the panel
(as previously noted).
• Trailer: 16 bits. These clocks allow the panel time to
transfer the data from the incoming latch to the pixel
memory.
Write Multiple Lines
Multiple lines can be updated quickly with this com-
mand. A line address is still used so the lines do not
have to be successive.
This command begins the same as the Write Line
command; using the same Write Line command bits
and data bits. See Figure 4.
Figure 3. Write Line Data String
Figure 4. Write Multiple Lines Data String, First Line
1 V 0 0 0 0 0 0 a a a a a a a a
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Line
Number
Command Data Trailer
LCD45-3
1 V 0 0 0 0 0 0 a a a a a a a a
0 0 0 0 0 0 0 0
Line
Number
Command Data Trailer
LCD45-6