Datasheet
TSX1
TSX2
TSY1
TSY2
R
X1
R
X2
R
Y1
R
Y2
R
C
PMOS
NMOS
TSREF
TGATE
TO ADC
XPOSITIONMEASUREMENT
TSX1
TSX2
TSY1
TSY2
R
X1
R
X2
R
Y1
R
Y2
R
C
PMOS
NMOS
TSREF
TGATE
TO ADC
Y POSITIONMEASUREMENT
TPS65070, TPS65072, TPS65073
TPS650731, TPS650732, TPS650701, TPS650702, TPS650721
SLVS950G –JULY 2009–REVISED MAY 2013
www.ti.com
Table 3. TSC Equations (continued)
MEASUREMENT CHANNEL EQUATION
X position AD_IN14 X
pos
= R
x2
/ (R
x1
+ R
x2
) = R
x2
/ Rx
R
x2
= V
ADC
x R
x
/ VTSREF; R
x1
= Rx – R
x2
X
pos
= ADRESULT / 1024
Y position AD_IN14 Y
pos
= R
y2
/ (R
y1
+ R
y2
) = R
y2
/ Ry
R
y2
= V
ADC
x R
y
/ VTSREF; R
y1
= Ry – R
y2
Y
pos
= ADRESULT / 1024
Pressure AD_IN14 Rc = R – R
x1
//R
x2
– R
y1
//R
y2
R = VTSREF/ [(V
ADC
/ 22k) × 150]
R
x1
//R
x2
= Rx × X
pos
× (1 – X
pos
)
R
y1
//R
y2
= Ry × Y
pos
× (1 – Y
pos
)
Performing Measurements Using the Touch Screen Controller
In order to take measurements with the touch screen controller, the ADC has to be enabled and configured for
use with the touch screen controller (TSC) first. In case the TSC is planned to be operated interrupt driven, the
TSC needs to be in TSC standby mode per default. Only in TSC standby mode an interrupt is generated based
on a touch of the screen. The TSC should therefore be in this mode until a touch is detected. Afterwards, the
TSC has to be configured for x-position measurement followed by y-position measurement. Now, the TSC can be
set to TSC standby again to wait for the next touch of the screen. For a non-interrupt driven sequence, see
TSCMODE. Register Address: 08h (page 50) in the Registers section. A typical interrupt driven sequence is
given below:
• Set TSCMODE to 101 to set TSC to TSC standby, so an interrupt is generated when the screen is touched
• Set Bit AD enable = 1 to provide power to the ADC
• Set input select for the ADC in register ADCONFIG to 1110 (AD_IN14 selected)
• In register INT, set MASK TSC = 1 to unmask the interrupt on a touch of the touch screen
• Read Bit TSC INT as it will be set after the TSC has been configured. Reading clears the interrupt.
• After a touch was detected, an interrupt is generated by INT pin going LOW
• Read Bit TSC INT to clear the interrupt
• Set TSCMODE to 000 to select x-position measurement
• Start an ADC conversion by setting CONVERSION START =1; wait until END OF CONVERSION = 1
• Read register ADRESULT_1 and AD_RESULT_2
• Set TSCMODE to 001 to select y-position measurement
• Start an ADC conversion by setting CONVERSION START =1; wait until END OF CONVERSION = 1
• Read register ADRESULT_1 and AD_RESULT_2
• Set TSCMODE to 101 to set TSC to TSC standby again
Figure 35. Two Position Measurement
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