Datasheet

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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 F
out
(MHz) % Error
F
out
(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 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 0 0 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
Table 23 .
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 RES RES RES RES RES RES 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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