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*Atenção: as imagens são meramente ilustrativas.
Overview
The AD Keypad provides 16 push buttons, and takes up only 1 AD port for controlling. It's suitable for applications where the AD ports are sufficient yet I/O ports are lacking of.
Features
16 push buttons, detection interface
Photos
Parameters and How to
Parameters and Sampling
- AD ideal value: when button pressed, Viv = (button index / 16) x Vref
AD real value: when button pressed, Vrv = (1 ± 6%) x Viv
For instance, suppose Vref = 5, 8th button was pressed, then Viv = (8 / 16) x 5 = 2.5, Vrv = (1 ± 6%) x 2.5, equals to 2.35-2.65
- Abbreviation
- Vref: AD reference voltage
- iv: ideal value
- rv: real value
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ADC Value Detection Range
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Measurement Data (Vref=3.3V)
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Measurement Data (Vref = 5V)
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Buttons
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10-bit ADC
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8-bit ADC
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Real Value
Sampling (V)
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Error (V)
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Ideal Value (V)
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Real Value
Sampling (V)
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Error (V)
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Ideal Value(V)
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0
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0-4
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0-1
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0
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0
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0
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0
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0
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0
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1
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(1±6%)x64
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(1±6%)x16
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0.2054
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-0.00085
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0.20625
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0.3112
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-0.0013
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0.3125
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|---|
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2
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(1±6%)x128
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(1±6%)x32
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0.4117
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-0.0008
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0.4125
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0.6238
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-0.0012
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0.625
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|---|
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3
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(1±6%)x192
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(1±6%)x48
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0.6233
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0.00455
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0.61875
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0.9444
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0.0069
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0.9375
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|---|
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4
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(1±6%)x256
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(1±6%)x64
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0.8242
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-0.0008
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0.825
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1.2487
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-0.0013
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1.25
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|---|
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5
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(1±6%)x320
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(1±6%)x80
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1.0304
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-0.00085
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1.03125
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1.5612
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-0.0013
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1.5625
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|---|
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6
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(1±6%)x384
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(1±6%)x96
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1.2355
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-0.002
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1.2375
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1.8719
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-0.0031
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1.875
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|---|
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7
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(1±6%)x448
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(1±6%)x112
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1.4448
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0.00105
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1.44375
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2.189
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0.0015
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2.1875
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8
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(1±6%)x512
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(1±6%)x128
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1.6541
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0.0041
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1.65
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2.5061
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0.0061
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2.5
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9
|
(1±6%)x576
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(1±6%)x144
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1.8637
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0.00745
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1.85625
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2.8237
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0.0112
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2.8125
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10
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(1±6%)x640
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(1±6%)x160
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2.0732
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0.0107
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2.0625
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3.1411
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0.0161
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3.125
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11
|
(1±6%)x704
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(1±6%)x176
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2.2672
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-0.00155
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2.26875
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3.435
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-0.0025
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3.4375
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|---|
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12
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(1±6%)x768
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(1±6%)x192
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2.4712
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-0.0038
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2.475
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3.7441
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-0.0059
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3.75
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|---|
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13
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(1±6%)x832
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(1±6%)x208
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2.6789
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-0.00235
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2.68125
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4.0588
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-0.0037
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4.0625
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14
|
(1±6%)x896
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(1±6%)x224
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2.8902
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0.0027
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2.8875
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4.3789
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0.0039
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4.375
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15
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(1±6%)x960
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(1±6%)x240
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3.1092
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0.01545
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3.09375
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4.7107
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0.0232
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4.6875
|
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How to detect and handle in your code
For 10-bit ADC, the 8th button generates ADC value between (1±6%)x512, the equivalence of "481-543". If the ADC value had been detected to be "510-518" in the code, the 8th button's supposed to have been pressed.
For 8-bit ADC, the 8th button generates ADC value between (1±6%)x128, the equivalence of "120-136". If the ADC value had been detected to be "124-128" in the code, the 8th button's supposed to have been pressed.
Downloads
Development resources: demo codes, schematic, datasheets, etc.
Wiki: www.waveshare.com/wiki/AD_Keypad
