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Features
• Complete Touchscreen Module:
– Projected Capacitive Multi Touch Controller
– 4.3in LCD
– 4 Capacitive “Navigation” Keys
– 200 bytes non-volatile serial EEPROM
• Touch:
– Atmel maXTouch™ mXT336S Touch Controller
– Supports up to 10 touches
• Display:
– 480x272 resolution
– Himax HX8257-A driver IC
– 20 ms response time
– White LED backlight
• Navigation Keys:
– Atmel AT42QT1070 QTouch™ Button Sensor IC
• Cover Panel:
– 1.1mm Soda Lime Glass
PDA TM4301:
4.3in PCAP
Touch Module
1403-2-4
TM4301
2 PDA TM4301: 4.3in PCAP Touch Module 1403-2-4
Contents
1 Module Overview 4
1.1 PCB Connections 4
1.2 UNUSED - Alternate Touch Sensor Interface J1 5
1.3 Debug Connector J2 5
1.4 Host Connector J3 5
1.5 Host Connector J4 6
1.6 Host Interface (Combined) J5 7
1.7 Display Flex Connector J7 8
1.8 Touch Sensor Flex Connector J8 9
2 Overview of the 4.3in PCAP Touch Module 10
2.1 Introduction 10
2.2 Understanding Unfamiliar Concepts 11
2.3 LCD Panel 11
2.4 maXTouch Capacitive Touchscreen Controller 11
2.4.1 maXTouch Controller Interface 12
2.5 QTouch Capacitive Button Controller 12
2.5.1 QTouch Controller Interface 12
2.6 Serial EEPROM 13
3 Getting Started 14
3.1 Hardware Connections 14
3.2 Software 14
3.3 Using the Touch Module 14
3.3.1 Navigation Keys 14
3.3.2 Evaluating the Touch Module 15
4 Specifications 16
4.1 Mechanical Specifications 16
4.2 Absolute Maximum Specifications 17
4.3 Recommended Operating Conditions 18
4.4 DC Specifications 18
4.5 I2C-compatible Bus Specifications 18
4.6 Power Consumption 18
4.7 Part Number 18
5 I2C Basics (I2C-compatible Operation) 19
5.1 Interface Bus 19
5.2 Transferring Data Bits 19
4 PDA TM4301: 4.3in PCAP Touch Module 1403-2-4
1 Module Overview
1.1 PCB Connections
Figure 1 - PCB Connectors
NOTE: Connector J7 is on the bottom side of the PCB.
NOTE: Insert flex in Connector J5 with contacts facing DOWN.
The following notations are used for pin descriptions:
I
Input only
OD
Open drain output
O
Output only, push-pull
P
Ground or power
MXT
maXTouch touchscreen
QT
QTouch Button Controller
EE
Serial EEPROM
LCD
LCD Panel
NOTE: Inputs and output are defined from the standpoint of the Touch Module.
AT MEL
MXT336S
D S24B33
J3
J2
J7
J8
J4
J5
Touch Sensor
Flex
Host
Debug
Display
Flex
Host
Combined
Host
Pin 1
Pin 1
Pin 1
Pin 1
Pin 1
Pin 1
TM4301: 4.3in PCAP Touch Module
5
1.2 UNUSED - Alternate Touch Sensor Interface J1
NOTE: Connector J1 is not populated or used on the TM4301 Module.
1.3 Debug Connector J2
Connector J2 carries signals used to debug the MaXTouch Touch Controller and QTouch Button Controller.
Pin
Type
Description
MXT
QT
Pin
Type
Description
MXT
QT
1
P
+5Vdc
6
I/O
I2C SCL
2
O
~QT_CHG
7
-
N/C
3
O
~MXT_CHG
8
P
GND
4
-
N/C
9
O
DBG DATA
5
I
I2C SDA
10
O
DBG CLK
1.4 Host Connector J3
Connector J3 connects to the host and carries signals between the host and (1) the MaXTouch Touch Controller,
(2) the QTouch Button Controller and (3) LCD Panel.
NOTE: J3 (and J4) should not be used when J5 is in use.
Pin
Type
Description
MXT
LCD
QT
EE
Pin
Type
Description
MXT
LCD
QT
EE
1
-
N/C
16
I
LCD_DATA_12 / G4
2
P
GND
17
P
GND
3
-
N/C
18
I
LCD_DATA_0 / B0
4
P
GND
19
I
LCD_DATA_1 / B1
5
O
~MXT_CHG
20
I
LCD_DATA_2 / B2
6
O
~QT_CHG
21
I
LCD_DATA_3 / B3
7
I
I2C SCL
22
I
LCD_DATA_4 / B4
8
I/O
I2C SDA
23
I
LCD_DATA_5 / B5
9
P
GND
24
I
LCD_DATA_6 / B6
10
I
LCD_DATA_15 / G7
25
I
LCD_DATA_7 / B7
11
P
GND
26
I
LCD_DATA_8 / G0
12
I
LCD_DATA_13 / G5
27
I
LCD_DATA_9 / G1
13
P
GND
28
I
LCD_DATA_10 / G2
14
I
LCD_DATA_14 / G6
29
I
LCD_DATA_11 / G3
15
P
GND
30
P
GND
6 PDA TM4301: 4.3in PCAP Touch Module 1403-2-4
1.5 Host Connector J4
Connector J4 connects to the host and carries signals between the host and (1) the LCD Panel and (2) serial
EEPROM.
NOTE: J4 (and J3) should not be used when J5 is in use.
Pin
Type
Description
MXT
LCD
QT
EE
Pin
Type
Description
MXT
LCD
QT
EE
1
P
+5Vdc
21
P
GND
2
P
GND
22
P
GND
3
P
+5Vdc
23
-
N/C
4
P
GND
24
-
N/C
5
I
LCD_DATA_16 / R0
25
-
N/C
6
I
LCD_DATA_17 / R1
26
-
N/C
7
I
LCD_DATA_18 / R2
27
-
N/C
8
I
LCD_DATA_19 / R3
28
I/O
One-Wire Interface
9
I
LCD_DATA_20 / R4
29
P
GND
10
I
LCD_DATA_21 / R5
30
P
GND
11
I
LCD_DATA_22 / R6
31
O
MISO
12
I
LCD_DATA_23 / R7
32
I
MOSI
13
P
GND
33
I
SCK
14
P
GND
34
I
~SS
15
I
DISP (Display Enable)
35
-
N/C
16
I
Backlight PWM
36
O
Module Presence Detect
17
I
VSYNC
37
-
N/C
18
I
HSYNC
38
-
N/C
19
I
DE
39
P
GND
20
I
PCLK
40
P
GND
TM4301: 4.3in PCAP Touch Module
7
1.6 Host Interface (Combined) J5
Connector J5 connects to the host and carries the combined signals of J3 and J4. It provides an alternate
interface between the host and (1) the MaXTouch Touch Controller, (2) the QTouch Button Controller, (3) LCD
Panel, and (4) serial EEPROM.
Suggested Flex:
Manufacturer P/N: Wurth Electronics #687 650 100 002
Description: 0.5mm pitch 50 position FFC, Length 100mm
Flex should be inserted Connector J5 with contacts facing DOWN.
NOTE: J5 should not be used when J3 and J4 are in use.
Pin
Type
Description
MXT
LCD
QT
EE
Pin
Type
Description
MXT
LCD
QT
EE
1
I/O
One-Wire Interface
26
I
LCD_DATA_19 / R3
2
P
GND
27
P
GND
3
I
LCD_DATA_0 / B0
28
I
LCD_DATA_20 / R4
4
I
LCD_DATA_1 / B1
29
I
LCD_DATA_21 / R5
5
I
LCD_DATA_2 / B2
30
I
LCD_DATA_22 / R6
6
I
LCD_DATA_3 / B3
31
I
LCD_DATA_23 / R7
7
P
GND
32
P
GND
8
I
LCD_DATA_4 / B4
33
I
PCLK
9
I
LCD_DATA_5 / B5
34
I
VSYNC
10
I
LCD_DATA_6 / B6
35
I
HSYNC
11
I
LCD_DATA_7 / B7
36
I
DE
12
P
GND
37
I
SCK
13
I
LCD_DATA_8 / G0
38
I
MOSI
14
I
LCD_DATA_9 / G1
39
O
MISO
15
I
LCD_DATA_10 / G2
40
I
~SS
16
I
LCD_DATA_11 / G3
41
I
DISP
17
P
GND
42
I
I2C SDA
18
I
LCD_DATA_12 / G4
43
I/O
I2C SCL
19
I
LCD_DATA_13 / G5
44
O
~MXT_CHG
20
I
LCD_DATA_14 / G6
45
O
~QT_CHG
21
I
LCD_DATA_15 / G7
46
I
LCD_PWM
22
P
GND
47
I
~RESET
23
I
LCD_DATA_16 / R0
48
P
+5Vdc
24
I
LCD_DATA_17 / R1
49
P
+5Vdc
25
I
LCD_DATA_18 / R2
50
P
GND
8 PDA TM4301: 4.3in PCAP Touch Module 1403-2-4
1.7 Display Flex Connector J7
Connector J7 connects to the LCD panel flex and carries signals between the host and the LCD Panel.
Note: J7 is located on the back side of the PCB.
Pin
Type
Description
Pin
Type
Description
1
P
LED-
21
O
LCD_DATA_0 / B0
2
P
LED+
22
O
LCD_DATA_1 / B1
3
P
GND
23
O
LCD_DATA_2 / B2
4
P
+3.3Vdc
24
O
LCD_DATA_3 / B3
5
O
LCD_DATA_16 / R0
25
O
LCD_DATA_4 / B4
6
O
LCD_DATA_17 / R1
26
O
LCD_DATA_5 / B5
7
O
LCD_DATA_18 / R2
27
O
LCD_DATA_6 / B6
8
O
LCD_DATA_19 / R3
28
O
LCD_DATA_7 / B7
9
O
LCD_DATA_20 / R4
29
P
GND
10
O
LCD_DATA_21 / R5
30
O
PCLK
11
O
LCD_DATA_22 / R6
31
O
DISP
12
O
LCD_DATA_23 / R7
32
O
HSYNC
13
O
LCD_DATA_8 / G0
33
O
VSYNC
14
O
LCD_DATA_9 / G1
34
O
DE
15
O
LCD_DATA_10 / G2
35
-
N/C
16
O
LCD_DATA_11 / G3
36
P
GND
17
O
LCD_DATA_12 / G4
37
-
N/C
18
O
LCD_DATA_13 / G5
38
-
N/C
19
O
LCD_DATA_14 / G6
39
-
N/C
20
O
LCD_DATA_15 / G7
40
-
N/C
TM4301: 4.3in PCAP Touch Module
9
1.8 Touch Sensor Flex Connector J8
Connector J8 connects to the touch sensor flex and carries signals used by the maXTouch controller to detect
input on the touch sensor.
Pin
Type
Description
Pin
Type
Description
1
P
GND
21
I/O
X4
2
I/O
Y0
22
I/O
X5
3
I/O
Y1
23
I/O
X6
4
I/O
Y2
24
I/O
X7
5
I/O
Y3
25
I/O
X8
6
I/O
Y4
26
I/O
X9
7
I/O
Y5
27
I/O
X10
8
I/O
Y6
28
I/O
X11
9
I/O
Y7
29
I/O
X12
10
I/O
Y8
30
I/O
X13
11
I/O
Y9
31
I/O
X14
12
I/O
Y10
32
I/O
X15
13
I/O
Y11
33
I/O
X16
14
I/O
Y12
34
I/O
X17
15
I/O
Y13
35
I/O
X18
16
P
GND
36
I/O
X19
17
I/O
X0
37
I/O
X20
18
I/O
X1
38
I/O
X21
19
I/O
X2
39
I/O
X22
20
I/O
X3
40
I/O
GND or X23
10 PDA TM4301: 4.3in PCAP Touch Module 1403-2-4
2 Overview of the 4.3in PCAP Touch Module
2.1 Introduction
The 4.3in PCAP Touch Module is a touchscreen module offering best-in-class projected capacitance multi-touch
functionality combined with a 4.3in LCD panel. The module is configured for development and evaluation with
several Atmel ARM-based EK solutions as well as development and integration with a custom host system.
For convenience, this module features host interface connectors (J3 and J4) positioned for direct installation on
Atmel ARM-based EK boards.
As shown in Figure 2 below, the module provides host access to several sub-system components to maximize
effective integration.
Figure 2 - Functional Block Diagram
HOST
Touch sensor
LCD Panel
TM4301 - Touch Module
QT1070
Nav Keys
mXT336S
DS24B33
Capacitive Button
Controller
Capacitive Touchscreen
Controller
Serial EEPROM
PCB
J3
J4
J8
J7
J5
TM4301: 4.3in PCAP Touch Module
11
2.2 Understanding Unfamiliar Concepts
Throughout this document, the functionality of the module sub-system will be outlined and summarized. However,
the user is encouraged to refer to the resources and documents below in order to gain a more thorough
understanding of each sub-system.
• For a basic overview of I2C communication, refer to Section 5 of this document
• Atmel maXTouch mXT336S Datasheet (www.atmel.com)
• Atmel QTouch QT1070 Datasheet (www.atmel.com)
• Maxim DS24B33 Datasheet (www.maximintegrated.com)
In addition, when developing or evaluating with the Atmel ARM-based EK’s, it is recommended that the user visit
www.at91.com which contains a broad range of resources for the EK’s and the ARM devices they feature.
2.3 LCD Panel
The module provides the host with a direct connection from the host (Connector J5 or Connectors J3 and J4) to the
LCD panel interface (Connector J7). Aside from generating supply voltages for the LED backlight and providing
backlight control to the host, no display panel control is performed by the module.
The LCD panel features a Himax HX8257-A internal driver IC.
2.4 maXTouch Capacitive Touchscreen Controller
The module touch screen interface is based on the Atmel maXTouch mXT336S Touch Controller and operates on
the touch sensor at connector J8.
The touch controller scans the touch sensor and will signal the host with an active low interrupt signal (~MXT_CHG
on J3 or J5) when new touch data is available. Data communication with the maXTouch controller is performed
over a shared I2C interface (I2C SCL and I2C SDA on J3 or J5). The I2C address of the touch controller can be
configured by populating R2 or R3 (shown below in Figure 3) according to Table 2-1 below. The PCB ships with
R3 populated – thus the I2C address is set to 0x4A by default.
NOTE: The TM4301 does not have pull-up resistors on the I2C SCL and SDA lines. A pull-up resistor for
the maXTouch ~CHG interrupt signal is located at R1.
12 PDA TM4301: 4.3in PCAP Touch Module 1403-2-4
Figure 3 - Touch Controller I2C Address Selection
Table 2-1 - Touch Controller I2C Address Selection
R2
R3
I2C Address
DNP
0 Ω
0x4A
0 Ω
DNP
0x4B
Note: 0x4A is the default I2C address
2.4.1 maXTouch Controller Interface
Details of the maXTouch communication protocol are beyond the scope of this document. However information is
provided below to facilitate evaluation and initial development.
This module is pre-loaded with a configuration already optimized for this touch sensor and panel, so the
developer need only focus on interfacing with the device. When developing the maXTouch controller
interface during evaluation and host development, care should be taken to avoid changing the maXTouch
configuration or committing changes to NV storage on the maXTouch controller.
To get started with host interface development, the user is strongly encouraged to leverage existing code available
from the resources outlined in Sections 3.2
2.5 QTouch Capacitive Button Controller
The module’s “nav key” interface is based on the Atmel QT1070 7-Channel Capacitive Sensor Driver.
The button controller scans the 4 capacitive nav keys (K1, K2, K3 and K4) and will signal the host with an active
low interrupt signal (~QT_CHG on Connector J3 or J5) when a touch event has occurred. Data communication
with the QT1070 controller is performed over a shared I2C interface (I2C SCL and I2C SDA on J3 or J5). The I2C
address of the button controller is 0x1B and cannot be changed.
NOTE: The TM4301 does not have pull-up resistors on the I2C SCL and SDA lines. A pull-up resistor for
the QTouch ~CHG interrupt signal is located at R22.
2.5.1 QTouch Controller Interface
Details of the QTouch communication protocol are beyond the scope of this document. The user is encouraged
to review the QT1070 Datasheet (www.atmel.com).
ATMEL
MXT336S
J3
J8
TM4301: 4.3in PCAP Touch Module
13
2.6 Serial EEPROM
The module includes a DS24B33 Serial EEPROM providing 512 bytes of non-volatile storage. Data
communication with the EEPROM is performed over a One-Wire Interface. The EEPROM is not used by another
subsystem on the touch module and can be freely used by the host system for any purpose. For example, Atmel
ARM-based EK’s running Linux or Android operating systems use the pre-programmed contents of the EEPROM
to identify this module type.
NOTE: The user should take care if choosing to overwrite the pre-programmed EEPROM contents. As
noted above, certain builds of Linux or Android targeted for the Atmel ARM-based EKs use the EEPROM
contents to identify the module and may no longer recognize the module. The user is advised to backup
the EEPROM contents before overwriting.
The serial EEPROM communicates via a one-wire interface (One-wire Interface on J4 or J5). Refer to the
DS24B33 Datasheet (www.maximintegrated.com) for details.
14 PDA TM4301: 4.3in PCAP Touch Module 1403-2-4
3 Getting Started
This module was designed to install on a variety of Atmel ARM-based EK’s including the SAM9X5-EK,
SAM9N12-EK, SAMA5D3x-EK and the SAMA5D3 Xplained. This provides the fastest way to evaluate the
performance of the touchscreen and display using a familiar, full-featured OS.
The following sections provide basic information related to using and evaluating the Touch Module. Visit
Precision Design Associates website ( www.pdaatl.com ) or Atmel’s AT91 Community website ( www.at91.com )
for more information related to this touch module or guidance appropriate for your specific EK.
3.1 Hardware Connections
The module interfaces with the EK board via one of two methods depending on the EK. Refer to the specific EK
documentation to determine which method is appropriate:
the two large dual-row headers, J3 and J4
the flex connector, J5
3.2 Software
Several options exist when developing for the touch module whether targeting a custom host or an Atmel EK.
3.2.1.1 Atmel Software Framework
The Atmel Software Framework (asf.atmel.com) contains examples of code for interfacing with devices in the
maXTouch family of touch controllers. The capabilities of various maXTouch devices may differ, but the basic
communication protocol is common and can be applied to this module.
3.2.1.2 Linux Kernel / Android
The Linux Kernel (www.kernel.org) has included basic support for maXTouch touch devices since version 2.6.36.
The mainline driver has undergone considerable evolution since then.
Atmel hosts the AT91 community website with resources dedicated to developing their EKs for Android
( www.at91.com/android4sam/ ) and Linux ( www.at91.com/linux4sam/ )
In addition, Atmel maintains patches (www.github.com/atmel-maxtouch/linux) which provide numerous out-of-cycle
improvements to the mainline Linux Kernel driver.
3.3 Using the Touch Module
3.3.1 Navigation Keys
When using this module with one of the standard Atmel Android demo builds, the navigation keys function as
shown in Table 3-1 below:
TM4301: 4.3in PCAP Touch Module
15
Table 3-1 - Navigation Key Function (Android)
Key
Navigation Function
K1
Back
K2
Menu
K3
Home
K4
Power / Sleep
3.3.2 Evaluating the Touch Module
For effective evaluation of the module – the touch sensor and the LCD panel in particular – the user is encouraged to try
the following applications and tools depending on the host OS.
3.3.2.1 Android
The following Android apps available from Google Play:
TouchTest by Moonblink
Dotty by Gerry Steele
Multitouch Visible Test by Battery Powered Games
Screen Test by Amberfog
3.3.2.2 Linux
The user can perform simple touch / drawing test using the ts_test utility that is part of tslib.
16 PDA TM4301: 4.3in PCAP Touch Module 1403-2-4
4 Specifications
For complete specifications, refer to the datasheets listed in section 2.2 for the various sub-system components
outlined in sections 2.3 through 2.6.
4.1 Mechanical Specifications
Drawings and CAD models available upon request.
Figure 4 - Sensor Only Dimensions
Sensor (P/N: 90-00019-A1) may be purchased individually.
Minimum order quantities apply. Contact PDA for details.
39.2 mm
(FPC Max Width)
25.5 mm
(FPC Min Width)
49.87 mm
Cover Glass Profile
124.46mm x 83.82mm
R6mm in corners 105.5 mm
(Sensor PET Outline)
67.2 mm
(Sensor PET Outline)
14.32 mm
(Viewable to
Cover Glass Edge)
14.6 mm
(Viewable to
Cover Glass Edge)
54.66 mm (Viewable)
95.84 mm (Viewable)
1.2 mm
(Cover Panel + Optically
Clear Adhesive)
0.35 mm (Sensor)
0.076 mm (FPC)
Viewed from
user side
User side
PCB contacts
face down
LCD side
PIN 1
PIN 40
TM4301: 4.3in PCAP Touch Module
17
Figure 5 – Module Dimensions
4.2 Absolute Maximum Specifications
Parameter
Value
Operating temp
0oC to + 70oC
Storage temp
-40oC to + 85oC
Vdd
-0.5 to +6V
Max continuous pin current, any control or drive pin
±40 mA
Voltage forced onto any pin
-0.5V to (Vdd + 0.5) Volts
CAUTION: Stresses beyond those listed under Absolute Maximum Specifications may cause permanent
damage to the device. This is a stress rating only and functional operation of the device at these or other
conditions beyond those indicated in the operational sections of this specification are not implied. Exposure to
absolute maximum specification conditions for extended periods may affect device reliability.
ATM EL
MXT336S
DS24 B33
43.2 mm
Glass Profile
124.46mm x 83.82mm
R6mm in corners
119.5 mm
(Frame Length)
17.08 mm
(Cover Panel rear surface
to Mounting Boss)
80.26 mm
(Frame Width)
5.08 mm
(PCB Component Clearance)
63.5 mm
(PCB Width)
7.56 mm
134.6 mm
(PCB Length)
18 PDA TM4301: 4.3in PCAP Touch Module 1403-2-4
4.3 Recommended Operating Conditions
Parameter
Value
Vin
5.0V ±5 percent
Supply ripple + noise
±20 mV
4.4 DC Specifications
Vin = 5.0V, Vdd=3.3VdcTa = recommended range, unless otherwise noted
Parameter
Description
Min
Typ
Max
Units
Notes
VIL
Low input logic level
- 0.5
–
0.3 Vdd
V
1.8V <Vdd <3.3V
VHL
High input logic level
0.7 Vdd
–
Vdd + 0.5
V
1.8V <Vdd <3.3V
VOL
Low output voltage
–
–
0.2Vdd
V
VOH
High output voltage
0.8Vdd
–
–
V
IIL
Input leakage current
–
–
1
µA
4.5 I2C-compatible Bus Specifications
Parameter
Operation
Touchscreen Controller Address
Selectable: 0x4A or 0x4B
Navigation Key Controller Address
0x1B
Maximum bus speed (SCL)
400 kHz
I2C Specification
Version 2.1
4.6 Power Consumption
Vdd (V)
Mode
Idd (mA)
3.3Vdc
mXT336S in Free Run, LCD backlight on
maximum intensity
200
4.7 Part Number
Part Number
Description
90-00002-C0
TM4301: 4.3” Touchscreen Module
TM4301: 4.3in PCAP Touch Module
19
5 I2C Basics (I2C-compatible Operation)
5.1 Interface Bus
The device communicates with the host over an I2C-compatible bus, in accordance with version 2.1 of the I2C
specification. The following sections give an overview of the bus; more detailed information is available from
www.i2C-bus.org. Devices are connected to the I2C-compatible bus as shown in Figure 6 both bus lines are
connected to Vdd via pull-up resistors. The bus drivers of all I2C-compatible devices must be open-drain type. This
implements a wired “AND” function that allows any and all devices to drive the bus, one at a time. A low level on
the bus is generated when a device outputs a zero.
Figure 6. I2C-compatible Interface Bus
5.2 Transferring Data Bits
Each data bit transferred on the bus is accompanied by a pulse on the clock line. The level of the data line must be
stable when the clock line is high; the only exception to this rule is for generating START and STOP conditions.
Figure 7. Data Transfer
5.3 START and STOP Conditions
The host initiates and terminates a data transmission. The transmission is initiated when the host issues a START
condition on the bus, and is terminated when the host issues a STOP condition. Between the START and STOP
conditions, the bus is considered busy. As shown in Figure 8 START and STOP conditions are signaled by
changing the level of the SDA line when the SCL line is high.
SDA
SCL
Device 1 Device 2 Device 3 Device n
Vdd
R1 R2
SDA
SCL Data Stable Data Stable
Data Change
20 PDA TM4301: 4.3in PCAP Touch Module 1403-2-4
Figure 8. START and STOP Conditions
5.4 Address Byte Format
All address bytes are 9 bits long. They consist of 7 address bits, one READ/WRITE control bit and an acknowledge
bit. If the READ/WRITE bit is set, a read operation is performed. Otherwise a write operation is performed. An
address byte consisting of a slave address and a READ or a WRITE bit is called SLA+R or SLA+W, respectively.
When the device recognizes that it is being addressed, it acknowledges by pulling SDA low in the ninth SCL (ACK)
cycle.
The most significant bit of the address byte is transmitted first.
Figure 9. Address Byte Format
5.5 Data Byte Format
All data bytes are 9 bits long, consisting of 8 data bits and an acknowledge bit. During a data transfer, the host
generates the clock and the START and STOP conditions. The slave device is responsible for acknowledging the
reception. An acknowledge (ACK) is signaled by the slave device pulling the SDA line low during the ninth SCL
cycle. If the slave device leaves the SDA line high, a NACK is signaled.
Figure 10. Data Byte Format
SDA
SCL
START STOP
SDA
SCL
START 1 2 7 8 9
R/WAddr LSB ACKAddr MSB
SLA+R/W 1 2 7 8 9
R/WAddr LSB ACKAddr MSB
Aggregate
SDA
SDA from
Transmitter
SDA from
Receiver
SCL from
Master STOP or
Next Data ByteData Byte
TM4301: 4.3in PCAP Touch Module
21
5.6 Combining Address and Data Bytes into a Transmission
A transmission consists of a START condition, an SLA+R or SLA+W, one or more data bytes and a STOP
condition. The wired “ANDing” of the SCL line is used to implement handshaking between the host and the device.
The device extends the SCL low period by pulling the SCL line low whenever it needs extra time for processing
between the data transmissions.
Figure 11 shows a typical data transmission. Note that several data bytes can be transmitted between the SLA+R
or SLA+W and the STOP.
Figure 11. Byte Transmission
ACK
1 2 7 8 9
Data Byte
SDA
SCL
START
Data
LSB
Data
MSB
R/W
1 2 7 8 9
SLA+R/W
Addr
LSB
Addr
MSB ACK
STOP
22 PDA TM4301: 4.3in PCAP Touch Module 1403-2-4
6 Revision History
TM4301 Datasheet - 20140404.docx : 4/4/2014 5:26:00 PM
4/4/2014 5:26 PM Greg Sullivan
Revision No.
History
Rev1403-1-1
Rev1403-1-2
Initial Draft (unreleased)
Rev1403-1-3
Preliminary Release (limited release)
Rev1404-2-4
Initial Release
TM4301: 4.3in PCAP Touch Module
23
7 Notes
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