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TSC2301 DATA REGISTERS
X, Y, Z1, Z2, BAT1, BAT2, AUX1, AUX2, TEMP1, and TEMP2 REGISTERS
Keypad Data Register (Page 0, Address 04H)
DAC Data Register (Page 0, Address 0BH)
OPERATION - TOUCH SCREEN MEASUREMENTS
Conversion Controlled by TSC2301 Initiated at Touch Detect
TSC2301
SLAS371D – SEPTEMBER 2002 – REVISED AUGUST 2004
Table 28. PLL Settings (continued)
MCLK (MHz)
Desired
P
A
N
Actual Fout(MHz)
% Error
Fout(MHz)
19.68
22.5792
9
3
7
22.59556
0.072
The data registers of the TSC2301 hold data results from conversions or keypad scans, or the value of the DAC
output current. All of these registers default to 0000H upon reset, except the DAC register, which is set to 0080H,
representing the midscale output of the DAC.
The results of all A/D conversions are placed in the appropriate data register, as described in
Table 5 and
Table 3. The data format of the result word, R, of these registers is right-justified, as follows (assuming a 12-bit
conversion):
Bit 15
Bit 14
Bit
Bit 10 Bit 9 Bit 8
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
MSB
13
12
11
LSB
0
R11
R10
R9
R8
R7
R6
R5
R4
R3
R2
R1
R0
MSB
LSB
The keypad data register (Page 0, Address 04H) is formatted as follows:
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
MSB
LSB
K15
K14
K13
K12
K11
K10
K9
K8
K7
K6
K5
K4
K3
K2
K1
K0
This is the same format as used in the keypad mask register (Page 1, Address 10H). Each bit in these registers
represents one key on the keypad. A 16-key keypad is mapped into the keypad data register as shown in
The data to be written to the DAC is written into the DAC data register, which is formatted as follows:
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
MSB
LSB
RES
D7
D6
D5
D4
D3
D2
D1
D0
There are three different touch screen conversion modes available in the TSC2301: self-controlled or
PENIRQ-Initiated, host-initiated, and host-controlled. These three modes are described below.
In this mode, the TSC2301 detects when the touch panel is touched and causes the PENIRQ line to go low. At
the same time, the TSC2301 powers up its internal clock. It then turns on the Y-drivers, and after a programmed
panel voltage stabilization time, powers up the ADC and convert the Y coordinate. If averaging is selected,
several conversions may take place; when data averaging is complete, the Y coordinate result is stored in the Y
register.
This mode is recommended to fully utilize the integrated touch screen processing of the TSC2301 and
reduce the processing overhead and number of interrupts to the host processor. In this mode, the host
processor does not need to monitor PENIRQ, instead the host needs only to configure the TSC2301 once at
power-up, and then monitor DAV and read back data after a falling edge on DAV.
If the screen is still touched at this time, the X-drivers are enabled, and the process repeats, but measures
instead the X coordinate, storing the result in the X register.
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