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PmodCLP™ Reference Manual
Revised May 24, 2016
This manual applies to the PmodCLP rev. B
DOC#: 502-142
Copyright Digilent, Inc. All rights reserved.
Other product and company names mentioned may be trademarks of their respective owners.
Page 1 of 6
Overview
The Digilent PmodCLP is a 16×2 character LCD module that uses a 8-bit parallel data interface to let system boards
display up to 32 different characters out of over 200 possible options.
1 Functional Description
The PmodCLP utilizes a Samsung KS0066 LCD controller to display information to a Sunlike LCD panel. The module
can execute a variety of instructions, such as erasing specific characters, setting different display modes, scrolling,
and displaying user-defined characters.
2 Interfacing with the Pmod
The PmodCLP communicates with the host board via the GPIO protocol. This particular module requires specific
timings in order to program the KS0066 correctly, as per the KS0066 datasheet. These timings are described after
the pinout description table shown below:
The PmodCLP.
Features include:
PmodCLP™ Reference Manual
Copyright Digilent, Inc. All rights reserved.
Other product and company names mentioned may be trademarks of their respective owners.
Page 2 of 6
Header J1 - Top Half
Header J1 - Bottom Half
Header J2
Pin
Signal
Description
Pin
Signal
Description
Pin
Signal
Description
1
DB0
Data Bit 0
7
DB4
Data Bit 4
1
RS
Register Select: High for
Data Transfer, Low for
Instruction Transfer
2
DB1
Data Bit 1
8
DB5
Data Bit 5
2
R/W
Read/Write signal: High
for Read mode, Low for
Write mode
3
DB2
Data Bit 2
9
DB6
Data Bit 6
3
E
Read/Write Enable: High
for Read, falling edge
writes data
4
DB3
Data Bit 3
10
DB7
Data Bit 7
4
NC
Optional back-light
enable (not connected on
the PmodCLP
5
GND
Power Supply
Ground
11
GND
Power Supply
Ground
5
GND
Power Supply Ground
6
VCC
Positive
Power
Supply1
12
VCC
Positive
Power Supply¹
6
VCC
Positive Power Supply
Table 1. PmodCLP Connector Signals.
2.1 Timing Requirements
After power-on, at least 20ms must elapse before the “Function Set” instruction code can be
written to set the bus width, number of lines, and character patterns (8-bit interface, 2 lines,
and 5×8 dots are appropriate). After the Function Set instruction, at least 37us must elapse
before the “Display On/Off Control” instruction can be written (to turn the display on, turn the
cursor on or off, and set the cursor to blink or no blink). After another 37us, the “Clear
Display” instruction can be issued.
After another 1.52ms, the “Entry Mode Set” instruction can set address increment (or address
decrement) mode, and display shift mode (on or off). After this sequence, data can be written
into the DDRAM via the “Write data into RAM” to cause information to appear on the display.
Note that other compatible LCD controllers use similar start-up sequences which may not use
the same timings as the Samsung controller.
The table below lists the required bit order needed in order to send a variety of instructions to
the LCD controller on the PmodCLP. Before the 8 bits of parallel data (DB7 through DB0) are
sent, the output enable pin, E, must be brought to a high '1' state and then brought to a low
'0' state at end of the sequence in order to transfer the data bits to the LCD controller.
1
For Revision A of the PmodCLP this must be at 5V. For Revision B, this must be at 3.3V
Power On
Wait 20ms
Set Function
Wait 37 us
Display Set
Wait 37 us
Display Clear
Wait 1.52ms
OK
Figure 1. LCD startup sequence.
PmodCLP™ Reference Manual
Copyright Digilent, Inc. All rights reserved.
Other product and company names mentioned may be trademarks of their respective owners.
Page 3 of 6
2.2 PmodCLP Instruction Codes
Instruction
Instruction bit assignments
Description
RS
R/W
DB7
DB6
DB5
DB4
DB3
DB2
DB1
DB0
Clear Display
0
0
0
0
0
0
0
0
0
1
Clear display by writing
a 20H to all DDRAM
locations; set DDRAM
address register to 00H;
and return cursor to
home.
Return Home
0
0
0
0
0
0
0
0
1
X
Return cursor to home
(upper left corner), and
set DDRAM address to
0H. DDRAM contents
not changed.
Entry Mode
Set
0
0
0
0
0
0
0
1
I/D
SH
I/D = '1' for right-moving
cursor and address
increment; SH = '1' for
display shift (direction
set by I/D bit).
Display
On/Off
Control
0
0
0
0
0
0
1
D
C
B
Set display (D), cursor
(C), and blinking cursor
(B) on or off.
Cursor or
Display shift
0
0
0
0
0
1
S/C
R/L
X
X
S/C = '0' to shift cursor
right or left, '1' to shift
entire display right or
left (R/L = '1' for right).
Function Set
0
0
0
0
1
DL
N
F
X
X
Set interface data length
DL ('1' for 8 bit), number
of display lines N ('1' for
2 lines), font F ('0' for
5×8 dots)
Set CGRAM
Address
0
0
0
1
AC5
AC4
AC3
AC2
AC1
AC0
Set CGRAM address
counter AC5 - AC0
Set DDRAM
Address
0
0
1
AC6
AC5
AC4
AC3
AC2
AC1
AC0
Set CGRAM address
counter AC5 - AC0
Read busy
flag/address
0
1
BF
AC6
AC5
AC4
AC3
AC2
AC1
AC0
Read busy flag (BF) and
address counter AC6-
AC0
Write data
toRAM
1
0
D7
D6
D5
D4
D3
D2
D1
D0
Write data into DDRAM
or CGRAM, depending
on which address was
last set
Read data
toRAM
1
1
D7
D6
D5
D4
D3
D2
D1
D0
Read data into DDRAM
or CGRAM, depending
on which address was
last set
Table 2. LCD Instructions and codes.
Note: "X" represents a don't care bit.
PmodCLP™ Reference Manual
Copyright Digilent, Inc. All rights reserved.
Other product and company names mentioned may be trademarks of their respective owners.
Page 4 of 6
2.3 CGRAM and DDRAM
The LCD controller contains a character-generator ROM (CGROM) with 192 preset 5×8 character patterns (see
table 4 below), a character-generator RAM (CGRAM) that can hold 8 user-defined 5×8 characters, and a display
data RAM (DDRAM) that can hold 80 character codes. Character codes written into the DDRAM serve as indexes
into the CGROM (or CGRAM). Writing a character code into a particular DDRAM location will cause the associated
character to appear at the corresponding display location. Display positions can be shifted left or right by setting a
bit in the Instruction Register (IR). The write-only IR directs display operations (such as clear display, shift left or
right, set DDRAM address, etc). A busy flag shows whether the display has competed the last requested operation;
prior to initiating a new operation, the flag can be checked to see if the previous operation has been completed.
The display has more DDRAM locations than can be displayed at any given time. DDRAM locations 00H to 27H map
to the first display row, and locations 40H to 67H map to the second row. Normally, DDRAM location 00H maps to
the upper left display corner (the “home” location, and 40H to the lower left. Shifting the display left or right can
change this mapping. The display uses a temporary data register (DR) to hold data during DDRAM /CGRAM reads
or writes, and an internal address register to select the RAM location. Address register contents, set via the
Instruction Register, are automatically incremented after each read or write operation. The LCD display
uses ASCII character codes. Codes up through 7F are standard ASCII (which includes all “normal” alphanumeric
characters). Codes above 7F produce various international characters.
The predefined characters available to display (from the KS0066 datasheet) are shown in the table below:
PmodCLP™ Reference Manual
Copyright Digilent, Inc. All rights reserved.
Other product and company names mentioned may be trademarks of their respective owners.
Page 5 of 6
2.4 Predefined Character Table
Any external power applied to the PmodCLP must be at 5V for Revision A of the PmodCLP and at 3.3V for Revision
B of the PmodCLP.
PmodCLP™ Reference Manual
Copyright Digilent, Inc. All rights reserved.
Other product and company names mentioned may be trademarks of their respective owners.
Page 6 of 6
3 Physical Descriptions
The pins on the pin header are spaced 100 mil apart. The PCB is 2.3 inches long on the sides parallel to the pins on
the pin header and 3.3 inches long on the sides perpendicular to the pin header.