Matrix Orbital LCD2041 User manual

LCD2041
Technical Manual
Revision: 2.1

Contents
Contents ii
1 Getting Started 1
1.1 Display Options Available . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.3 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.4 Connecting to a PC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.5 Installing the Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.5.1 uProject . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2 Hardware Information 7
2.1 DB-9 Connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.1.1 Power Through DB-9 Jumper . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.2 Power/Data Connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2.2.1 Legacy Data Connector Jumpers . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.3 Protocol Select Jumpers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.4 General Purpose Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2.5 Manual Override . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3 Troubleshooting 15
3.1 The display does not turn on when power is applied. . . . . . . . . . . . . . . . . . . . . . . 15
3.2 The display module is not communicating. . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3.3 The display module is communicating, however text cannot be displayed. . . . . . . . . . . 16
4 Communications 16
4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
4.1.1 I2C Communication Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
4.1.2 I2C Transaction Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
4.1.3 Serial Communication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
4.2 Changing the I2C Slave Address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
4.3 Changing the Baud Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
4.4 Setting a Non-Standard Baud Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
5 Text 20
5.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
5.1.1 Character Set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
5.1.2 Control Characters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
5.2 Auto Scroll On . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
5.3 Auto Scroll Off . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
5.4 Clear Screen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
5.5 Changing the Startup Screen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
5.6 Set Auto Line Wrap On . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
5.7 Set Auto Line Wrap Off . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
5.8 Set Cursor Position . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Matrix Orbital LCD2041 ii

5.9 Go Home . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
5.10 Move Cursor Back . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
5.11 Move Cursor Forward . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
5.12 Underline Cursor On . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
5.13 Underline Cursor Off . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
5.14 Blinking Block Cursor On . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
5.15 Blinking Block Cursor Off . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
6 Special Characters 26
6.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
6.2 Creating a Custom Character . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
6.3 Saving Custom Characters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
6.4 Loading Custom Characters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
6.5 Save Startup Screen Custom Characters . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
6.6 Initialize Medium Number . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
6.7 Place Medium Numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
6.8 Initialize Large Numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
6.9 Place Large Number . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
6.10 Initialize Horizontal Bar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
6.11 Place Horizontal Bar Graph . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
6.12 Initialize Narrow Vertical Bar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
6.13 Initialize Wide Vertical Bar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
6.14 Place Vertical Bar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
7 General Purpose Output 32
7.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
7.2 General Purpose Output Off . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
7.3 General Purpose Output On . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
7.4 Set Startup GPO state . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
8 Display Functions 34
8.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
8.2 Display On . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
8.3 Display Off . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
8.4 Set Brightness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
8.5 Set and Save Brightness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
8.6 Set Contrast . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
8.7 Set and Save Contrast . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
9 Data Security 37
9.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
9.2 Set Remember . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
9.3 Data Lock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
9.4 Set and Save Data Lock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
9.5 Write Customer Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
9.6 Read Customer Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Matrix Orbital LCD2041 iii

10 Miscellaneous 39
10.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
10.2 Read Version Number . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
10.3 Read Module Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
11 Command Summary 42
11.1 Communications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
11.2 Text . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
11.3 Special Characters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
11.4 General Purpose Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
11.5 Display Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
11.6 Data Security . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
11.7 Miscellaneous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
11.8 Command By Number . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
12 Appendix 47
12.1 Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
12.1.1 Environmental . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
12.1.2 Electrical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
12.2 Optical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
12.3 Physical Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
12.4 Ordering Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
12.5 Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
12.6 Contacting Matrix Orbital . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
12.7 Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Matrix Orbital LCD2041 iv

1 Getting Started
Figure 1: LCD2041-WB
The LCD2041 is an intelligent LCD display designed to decrease development time by providing an
instant solution to any project. With the ability to communicate via serial RS-232/TTL and I2C protocols,
the versatile LCD2041 can be used with virtually any controller. The ease of use is further enhanced by an
intuitive command structure to allow display settings such as backlight brightness, contrast and baud rate to
be software controlled. Additionally, up to thirty-two custom charaters such as character sets for bar graphs,
medium and large numbers may be stored in the non-volitile memory to be easily recalled and displayed at
any time.
1.1 Display Options Available
The LCD2041 comes in a wide variety of colors including the standard yellow/green or inverse yellow,
the popular blue/white and the crisp white/grey as well as inversered which is excellent for viewing at night.
Extended voltage, and temperature options are also available, to allow you to select the display which will
best fit your project needs.
Matrix Orbital LCD2041 1

Figure 2: LCD2041 Options
1.2 Accessories
NOTE Matrix Orbital provides all the interface accessories needed to get your display
up and running. You will find these accessories and others on our e-commerce website at
http://www.matrixorbital.com. To contact a sales associate see Section 12.6 on page 51 for
contact information.
Figure 3: 5V Power Cable Adapter
Figure 4: 12V Power Cable Adapter (V/VPT
Models)
Matrix Orbital LCD2041 2

Figure 5: Breadboard Cable Figure 6: Serial Cable 4FT
Figure 7: Communication and 5V Power Cable
1.3 Features
•20 column by 4 line alphanumeric liquid crystal display
•Selectable communication protocol, serial at RS-232 or TTL levels or I2C
•Three, 5V -20mA, general purpose outputs for a variety of applications
•Lightning fast communication speeds, up to 57.6 kbps for RS-232 and 100 kbps for I2C
•Default 19.2 kbps serial communication speed
Matrix Orbital LCD2041 3

Figure 8: Aluminum Mountings
Figure 9: Mounting Kits
Matrix Orbital LCD2041 4

•Extended temperature available for extreme environments of -20C to 70C
•Extended voltage and efficient power supply available
•Built in font with provision for up to 8 user defined characters
•Use of up to 127 modules on the same 2 wire I2C interface
•Ability to add a customized splash / startup screen
•Software controlled contrast and brightness with configurable time-out setting up to 90 minutes
•Horizontal or vertical bar graphs
•Fits Matrix Orbital’s mountings without any modifications
1.4 Connecting to a PC
The LCD2041 connects seamlessly to a PC and it is an excellent means of testing the functionality. To
connect your display to a PC, you will require a standard RS-232 9-pin serial cable such as the one pictured
in figure 6 on page 3, as well as a modified 5V power adapter such as the one pictured in figure 3 on page 2.
In order to connect your display to a personal computer follow these easy instructions:
1. Plug the serial cable into the com port you wish to use.
2. Connect the modified 5V power adapter to a power lead from your PC power supply (you will have to
open your computer case).
3. Connect the serial cable to the DB-9 connector on the back of the display.
4. Connect the 5V power adapter to the 4-pin connector on the back of the display.
WARNING DO NOT use the standard floppy drive power connector,
as this will not provide you with the correct voltage and will damage the
display module.
Figure 10: PC vs Matrix Orbital Display Module Wiring
Matrix Orbital LCD2041 5

1.5 Installing the Software
1.5.1 uProject
uProject was designed by Matrix Orbital to provide a simple and easy to use interface that will allow you
to test all of the features of our alpha numeric displays.
To install uProject from the Matrix Orbital CD, follow the following steps:
1. Insert the Matrix Orbital CD-ROM into the CD drive
2. Locate the file, uProject.exe, which should be in the “CD-drive:\Download” directory.
3. Copy uProject.exe to a directory that you wish to run it from.
4. Double click on "uProject.exe"
Be sure to check the information selected in the COM Setup the first time uProject is run. Once this infor-
mation is entered correctly the program can be used to control all functions of the graphic display.
Comport The serial port the display
is plugged in to.
Baudrate The communication speed
the display
module is set to. (Default
19,200)
Figure 11: uProject Settings
NOTES
•uProject and other alphanumeric software may also be downloaded from Matrix Or-
bital’s support site at http://www.matrixorbital.ca/software/software_alpha/
Matrix Orbital LCD2041 6

2 Hardware Information
Refer to the following diagram for this chapter:
1DB-9 Connector 5Power / Data Connector
2Power Through DB9 Jumper 6Legacy Connector Jumper
3GPOs 7Protocol Select Jumpers
4Manual Override
Figure 12: LCD2041
2.1 DB-9 Connector
The LCD2041 provides a DB-9 Connector to readily interface with serial devices which use the EIA232
standard signal levels of ±12V to ±12V. It is also possible to communicate at TTL levels of 0 to +5V by
setting the Protocol Select Jumpers to TTL. As an added feature it is also possible to apply power through
pin 9 of the DB-9 Connector in order to reduce cable clutter. However, in order to accomplish this you must
set the Power Through DB-9 Jumper.
Matrix Orbital LCD2041 7

Pin 2Tx \ SDA (I2C data)
Pin 3Rx \ SCL (I2C clock)
Pin 5GND
Pin 9PWR (Must solder Power Through DB-
9 Jumper. See table 1 on page 10 for
power requirements.)
Figure 13: RS-232 Pin out
2.1.1 Power Through DB-9 Jumper
In order to provide power through pin 9 of the DB-9 Connector you must place a solder jumper on the
Power through DB-9 Jumper pictured in figure 14 below. The LCD2041 allows all voltage models to use the
power through DB-9 option, see table 1 on page 10 for display module voltage requirements.
Matrix Orbital LCD2041 8

Matrix Orbital LCD2041 9

WARNING Do not apply voltage through pin 9 of the DB-9 connector
AND through the Power/Data Connector at the same time.
2.2 Power/Data Connector
ThePower/Data Connector provides a standard connector for powering the display module. The LCD2041
requires five volts for the standard display module, between nine to fifteen for the wide voltage (V) and be-
tween nine to thirty-five volts for the wide voltage with efficient power supply module (VPT). The voltage is
applied through pins one and four of the four pin Power/Data connector. Pins two and three are reserved for
serial transmission, using either the RS-232/TTL or the I2C protocol, depending on what has been selected
by the Protocol Select Jumpers. Pins two and three may be reversed by changing the Legacy Connector
Jumpers in order to be compatible with previous PCB revisions.
Pin 1PWR (See table 1)
Pin 2Rx \ SCL (I2C clock)
Pin 3Tx \ SDA (I2C data)
Pin 4GND
Figure 15: Power Connector and Pin out
Table 1: Power Requirements
Standard -V -VPT
Supply Voltage +5Vdc ±0.25V +9V to +15V +9V to +35V
Supply Current 11 mA typical
Supply Backlight Current 160 mA typical
WARNINGS
•Do not apply any power with reversed polarization.
•Do not apply any voltage other than the specified voltage.
Matrix Orbital LCD2041 10

2.2.1 Legacy Data Connector Jumpers
To reverse pins two and three of the Power/Data Connector remove the zero ohm resistors from the
Legacy Data Connector Jumpers, labeled with the =symbol and place them on the jumpers labeled with the
Xsymbol. This will allow you to transmit on pin two, and receive data on pin three instead of the default
of receiving on pin two and transmitting on pin three of the Power/Data Connector.
Power/Data Connector
=[Pin 2 Rx \ SCL (I2C clock)
Pin 3 Tx \ SDA (I2C data)
x[Pin 2 Tx \ SDA (I2C data)
Pin 3 Rx \ SCL (I2C clock)
Figure 16: Legacy Data Connector Jumpers
2.3 Protocol Select Jumpers
The Protocol Select Jumpers, pictured below in figure 17, provide the means necessary to toggle the
display module between RS-232, TTL and I2C protocols. As a default, the jumpers are set to RS-232 mode
with zero ohm resistors on the 232 jumpers. In order to place the display module in I2C mode you must
first remove the zero ohm resistors from the 232 jumpers and then solder the resistors on to the I2C jumpers.
The display will now be in I2C mode and have a default slave address of 0x50 unless it has been changed.
Similarly, in order to change the display to TTL mode, simply remove the zero ohm resistors from the 232
or I2C jumpers and solder them to the TTL jumpers.
Matrix Orbital LCD2041 11

Matrix Orbital LCD2041 12

2.4 General Purpose Outputs
A unique feature of the LCD2041 is the ability to control relays and other external devices using a
General Purpose Output, which can provide up to 20 mA of current and +5Vdc from the positive side of the
GPO. If the device, which is being driven by a GPO, requires a relatively high current (such as a relay) and
has an internal resistance of its own greater than 250 ohms, then the 240 ohm resistor, which is associated
with the GPO may be removed and replaced with a Jumper.
-GND
+MAX: 20 mA, +5Vdc
Figure 18: General Purpose Output
WARNING If connecting a relay, be sure that it is fully clamped using
a diode and capacitor in order to absorb any electro-motive force (EMF)
which will be generated.
2.5 Manual Override
The Manual Override is provided to allow the LCD2041 to be reset to factory defaults. This can be
particularly helpful if the display module has been set to an unknown baud rate or I2C Slave Address and
you are no longer able to communicate with it. If you wish to return the module to its default settings you
must:
1. Power off the display module.
2. Place a Jumper on the Manual Override pins.
3. Power up the display module.
4. The display module is now set to its default values listed below in table 2.
5. Edit and save settings.
Matrix Orbital LCD2041 13

Matrix Orbital LCD2041 14

Table 2: Default Values
Contrast 128
Backlight 255
Baud Rate 19.2 kbps
I2C Slave Address 0x50
Data Lock False
RS232AutoTransmitData True
NOTE The display module will revert back to the old settings once turned off, unless the
settings are saved.
3 Troubleshooting
3.1 The display does not turn on when power is applied.
•First, you will want to make sure that you are using the correct power connector. Standard floppy drive
power cables from your PC power supply may fit on the Power/Data Connector however they do not
have the correct pin out as can be seen in figure 10 on page 5. Matrix Orbital supplies power cable
adapters for connecting to a PC, which can be found in the Accessories Section on page 2.
•The next step is to check the power cable which you are using for continuity. If you don’t have an
ohm meter, try using a different power cable, if this does not help try using a different power supply.
•The last step will be to check the Power / Data Connector on the LCD2041. If the Power / Data
Connector has become loose, or you are unable to resolve the issue, please contact Matrix Orbital,
see 12.6 on page 51 for contact information.
3.2 The display module is not communicating.
•First, check the communication cable for continuity. If you don’t have an ohm meter, try using a
different communication cable. If you are using a PC try using a different Com Port.
•Second, please ensure that the display module is set to communicate on the protocol that you are
using, by checking the Protocol Select Jumpers. To change the protocol used by the display module
see Section 2.3 on page 11.
•Third, ensure that the host system and display module are both communicating on the same baud rate.
The default baud rate for the display module is 19200 bps.
•If you are communicating to the display via I2C please ensure that the data is being sent to the correct
address. The default slave address for the display module is 0x50.
NOTE I2C communication will always require pull up resistors.
•Finally, you may reset the display to it’s default settings using the Manual Override Jumper, see
Section 2.5 on page 13.
Matrix Orbital LCD2041 15

3.3 The display module is communicating, however text cannot
be displayed.
•A common cause may be that the contrast settings have been set to low. The solution to this problem
is to adjust the contrast settings. The default setting that will work in most environments is 128.
NOTE Optimal contrast settings may varyaccording to factors such as temperature, view-
ing angle and lighting conditions.
If you are unable to resolve any issue please contact Matrix Orbital. See 12.6 on page 51
for contact information.
4 Communications
4.1 Introduction
The commands listed in this chapter describe how to configure data flow on the LCD2041.
4.1.1 I2C Communication Summary
The LCD2041 is capable of communicating at 100 KHz in I2C mode, with 127 units addressable on a
single I2C communication line. However, in order to communicate via I2C you must first ensure that pull up
resistors, with a nominal value of 1K to 10K, are placed on the SCL and SDA communication lines coming
from pins two and three of the Data / Power Connector respectively. Data responses by the module are
automatically output via RS232, in case the host will be querying the module, it is necessary for the host
to inform the module that its responses are to be output via I2C. This can be done by sending command
254 /160 / 0 to turn off auto transmission of data in RS232. This will keep the data in the buffer until the
master clocks a read of the slave. The I2C data lines operate at 5V normally or 3.3V for -1U style units. The
LCD2041 uses 8-bit addressing, with the 8th or Least Significant Bit (LSB) bit designated as the read/write
bit, a 0 designates a write address and a 1 designates a read address. The default read address of the display
module will be 0x51, whereas the write address is 0x50 by default. This address may be changed by using
cmd 254 / 51 / <address>. The LCD2041 should only be sent addresses that are even (LSB is 0). When the
I2C master wishes to write to the display, the effective address is $50 (0101 0000) , since the LSB has to be
0 for an I2C master write. When the I2C master wishes to read the LCD2041, the effective address is $51
(0101 0001), since the LSB has to be 1 for an I2C master read.
If we take a standard Phillips 7 bit address of $45 (100 0101), Matrix Orbital’s LCD2041 would describe
this Phillips I2C address as $8A (1000 1010). The read address would be $8B (1000 1011).
The unit does not respond to general call address ($00).
When communicating in I2C the LCD2041 will send an ACK on the 9th clock cycle when addressed.
When writing to the display module, the display will respond with a ACK when the write has successfully
been completed. However if the buffer has been filled, or the module is too busy processing data it will
respond with a NAK. When performing a multiple byte read within one I2C transaction, each byte read from
the slave should be followed by an ACK to indicate that the master still needs data, and a NAK to indicate
Matrix Orbital LCD2041 16