ad7879-1acbz-rl Analog Devices, Inc., ad7879-1acbz-rl Datasheet - Page 20

• Manufacturer Part Number: ad7879-1acbz-rl
• Description: Low Voltage Controller For Touch Screens
• Manufacturer: Analog Devices, Inc.

AD7879
DETAILED REGISTER DESCRIPTIONS
All addresses and default values are expressed in hexadecimal.
Table 10. Control Register 1
Address
0x01
1
2
If GPIO is enabled, AUX and VBAT are both ignored. If AUX and VBAT are both selected, and GPIO is disabled, AUX is ignored, and VBAT is measured.
Note that these settings clear to 00 at the end of the conversion sequence if the conversion interval timer bits in Control Register 1 (0x01) Bits 7:0 = 0x00h at the end of
the conversion sequence.
Name
Disable PENIRQ
CHNL ADD[2:0]
ADC MODE[1:0]
ACQ[1:0]
TMR[7:0]
Data
Bit
15
14:12
11:10
9:8
7:0
Description
Pen interrupt enable.
0 = PENIRQ pin is enabled.
1 = PENIRQ is disabled and INT enabled.
ADC Channel address for manual conversion (mode 01).
111 = X+ input (Y position).
110 = Y+ input (X position).
101 = X+ (Z1) input for touch-pressure calculation.
100 = Y− (Z2) input (used for touch-pressure measurement).
011 = AUX input
010 = VBAT input
001 = temperature measurement.
000 = not applicable.
ADC mode.
00 = no conversion.
01 = single conversion
10 = conversion sequence (slave mode)
11 = conversion sequence (master mode).
ADC acquisition time.
00 = 4 clock periods (2 μs).
01 = 8 clock periods (4 μs).
10 = 16 clock periods (8 μs).
11 = 32 clock periods (16 μs).
Note that the acquisition time does not apply to the temperature sensor channels; the
temperature channel has a constant settling time of 16 μs.
Conversion interval timer.
Starts at 550 μs and continues to 9.440 ms in steps of 35 μs.
Note that in slave mode, the conversion interval timer starts to count as soon as the
conversion sequence is finished; in master mode, it starts to count again only if the screen
remains touched. If the screen is released, the timer stops counting and, on the next screen
touch, a conversion starts immediately.
1
1
.
.
2
Rev. 0 | Page 20 of 36
.
2
.
Default
Value
0x0000