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Conversion Controlled by Host (TSMode 3)
t
COORDINATE
+
OH1
f
OSC
)
ǒ
t
PRE
)t
SNS
)
OH
DLY2
f
OSC
Ǔ
)N @
ǒ(
B)2
)
@
f
OSC
f
ADC
)OH
CONV
Ǔ
@
ǒ
1
f
OSC
Ǔ
)
ǒ
L
PPRO
f
OSC
Ǔ
(8)
Programmed
forHost-
Controlled
Mode
(PSM=0)
CS
Deactivated
X
Scan
Mode
Programmedfor:
TurnOn
X+and
X
Drivers
-
(1)
Reading
Y-Data
Register
TouchisDetected
CS
Deactivated
NOTE:(1)Optional.Ifnotturnedon,itwillbeturnedonbytheScanmode,oncedetected.
Y
Scan
Mode
Programmedfor:
TurnOn
Y+and
Y
Drivers
-
(1)
Reading
X-Data
Register
CS
Deactivated
CS
Deactivated
Detecting
Touch
WaitingforHosttoWriteInto
ControlByte1D[6:3]
PINTDAV Programmed:
As ,
CFR2,D[15:14]=10
PENIRQ
As ,
CFR2,D[15:14]=11or01
DAV
As and ,
CFR2,D[15:14]=00
PENIRQ DAV
TouchisDetected
TouchisDetected
Sample,Conversion,
andPreprocessing
forXCoordinate
Detecting
Touch
Sample,Conversion,
andPreprocessing
forYCoordinate
Detecting
Touch
WaitingforHostto
WriteIntoControl
Byte1D[6:3]
WaitingforHosttoWriteInto
ControlByte1D[6:3]
t
COORDINATE
t
COORDINATE
TSC2005
SBAS379C – DECEMBER 2006 – REVISED MARCH 2008
In TSMode 3, the TSC2005 detects when the touch panel is touched and causes the internal Pen-Touch signal
to be active, which lowers the PINTDAV output if it is programmed as PENIRQ. The host recognizes the interrupt
request. Instead of starting a sequence in the TSC2005, which then reads each coordinate in turn, the host must
now control all aspects of the conversion. Generally, upon receiving the interrupt request, the host turns on the X
drivers. ( NOTE: If drivers are not turned on, the device detects this condition and turns them on before the scan
starts. This situation is why the event of turn on drivers is shown as optional in Figure 35 and Figure 36 .) After
waiting for the settling time, the host then addresses the TSC2005 again, this time requesting an X coordinate
conversion.
The process is then repeated for the Y and Z coordinates. The processes are outlined in Figure 35 and
Figure 36 . Figure 35 shows two consecutive scans on X and Y. Figure 36 shows a single Z scan.
The time needed to convert any single coordinate X or Y under host control (not including the time needed to
send the command over the SPI bus) is given by:
Where:
OH
DLY2
= total overhead time for t
PRE
and t
SNS
= 6 internal clock cycles.
Figure 35. Example of X and Y Coordinate Touch Screen Scan using TSMode 3
36 Submit Documentation Feedback Copyright © 2006 – 2008, Texas Instruments Incorporated
Product Folder Link(s): TSC2005