ad7879-1acbz-rl Analog Devices, Inc., ad7879-1acbz-rl Datasheet - Page 21

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

Table 11. Control Register 2
Address
0x02
1
This delay occurs before conversion of the X and Y coordinate channels (including Z1 and Z2) to allow for screen settling and before the first conversion to allow the
ADC to power up.
Name
PM[1:0]
GPIO EN
GPIO DAT
GPIO DIR
GPIO POL
SER/DFR
A[1:0]
M[1:0]
SW/RST
FCD[3:0]
Data
Bit
15:14
13
11
10
9
8:7
6:5
4
3:0
12
Description
ADC power management.
00 = full shutdown, the ADC, oscillator, BIAS, and temperature sensor are all powered down.
01 = analog blocks to be powered down depend on the ADC mode.
If ADC mode is master mode; the ADC, oscillator, BIAS, and temperature sensor are powered
down and must wake up when the user touches the screen.
If ADC mode is slave mode, the ADC and temperature sensor are powered down while not
being used. They wake up automatically when required. The oscillator and BIAS are powered
up because they are needed to measure time. This also applies to the single conversion mode.
10 = ADC, BIAS, the oscillator is powered up continuously, irrespective of ADC mode.
11 = as 01.
GPIO enable.
0 = AUX/VBAT channel active.
1 = GPIO enabled on AUX/VBAT/GPIO.
GPIO data bit.
GPIO direction.
0 = output.
1 = input.
GPIO polarity.
0 = the GPIO pin is active low.
1 = the GPIO pin is active high.
SER/DFR.
Selects normal (single-ended) or conversion.
0 = ratiometric (differential).
1 = normal (single-ended).
ADC averaging.
00 = 2 middle values averaged (1 measurement when median filter does not operate).
01 = 4 middle values averaged.
10 = 8 middle values averaged.
11 = 16 values averaged.
Median filter size.
00 = median filter does not operate.
01 = 4 measurements.
10 = 8 measurements.
11 = 16 measurements.
Software reset; digital part is reset when this bit is set.
ADC first conversion delay
Starts at 128 μs and goes all the way to 4.096 ms in steps of 128 μs.
1
.
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AD7879
Default
Value
0x4040