EVAL-AD7879EBZ View Datasheet(PDF) - Analog Devices
Part Name
Description
MFG CO.
'EVAL-AD7879EBZ' PDF : 36 Pages View PDF
Data Sheet
AD7879/AD7889
Table 13. Control Register 2
Address Bit Name Data Bit
0x02
PM[1:0] [15:14]
GPIO EN 13
GPIO DAT 12
GPIO DIR 11
GPIO POL 10
SER/DFR 9
AVG[1:0] [8:7]
MED[1:0] [6:5]
SW/RST 4
FCD[3:0] [3:0]
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
when 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, and oscillator are powered up continuously, irrespective of ADC mode.
11 = same as 01.
GPIO enable.
0 = AUX/VBAT channel active.
1 = GPIO enabled on AUX/VBAT/GPIO pin.
GPIO data bit.
GPIO direction.
0 = output.
1 = input.
GPIO polarity.
0 = GPIO pin is active low.
1 = GPIO pin is active high.
Selects normal (single-ended) or ratiometric (differential) conversion.
0 = ratiometric (differential).
1 = normal (single-ended).
ADC averaging.
00 = 2 middle values averaged (one measurement when median filter is disabled).
01 = 4 middle values averaged.
10 = 8 middle values averaged.
11 = 16 values averaged.
Median filter size.
00 = median filter disabled.
01 = 4 measurements.
10 = 8 measurements.
11 = 16 measurements.
Software reset; digital logic is reset when this bit is set.
ADC first conversion delay.1
Starts at 128 µs (default) and continues to 4.096 ms in steps of 128 µs (see Table 22).
Default Value
0x4040
1 This delay occurs before conversion of the X and Y coordinate channels (including Z1 and Z2) to allow screen settling and before the first conversion to allow the ADC
to power up.
Rev. D | Page 23 of 40
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