AD Keypad

WSM0051

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More info

16 buttons controlled by only 1 AD port

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
 ADC Value Detection RangeMeasurement Data (Vref=3.3V)Measurement Data (Vref = 5V)
Buttons10-bit ADC8-bit ADCReal Value 
Sampling (V)
Error (V)Ideal Value (V)Real Value 
Sampling (V)
Error (V)Ideal Value(V)
0 0-4 0-1 0 0 0 0 0 0
1 (1±6%)x64 (1±6%)x16 0.2054 -0.00085 0.20625 0.3112 -0.0013 0.3125
2 (1±6%)x128 (1±6%)x32 0.4117 -0.0008 0.4125 0.6238 -0.0012 0.625
3 (1±6%)x192 (1±6%)x48 0.6233 0.00455 0.61875 0.9444 0.0069 0.9375
4 (1±6%)x256 (1±6%)x64 0.8242 -0.0008 0.825 1.2487 -0.0013 1.25
5 (1±6%)x320 (1±6%)x80 1.0304 -0.00085 1.03125 1.5612 -0.0013 1.5625
6 (1±6%)x384 (1±6%)x96 1.2355 -0.002 1.2375 1.8719 -0.0031 1.875
7 (1±6%)x448 (1±6%)x112 1.4448 0.00105 1.44375 2.189 0.0015 2.1875
8 (1±6%)x512 (1±6%)x128 1.6541 0.0041 1.65 2.5061 0.0061 2.5
9 (1±6%)x576 (1±6%)x144 1.8637 0.00745 1.85625 2.8237 0.0112 2.8125
10 (1±6%)x640 (1±6%)x160 2.0732 0.0107 2.0625 3.1411 0.0161 3.125
11 (1±6%)x704 (1±6%)x176 2.2672 -0.00155 2.26875 3.435 -0.0025 3.4375
12 (1±6%)x768 (1±6%)x192 2.4712 -0.0038 2.475 3.7441 -0.0059 3.75
13 (1±6%)x832 (1±6%)x208 2.6789 -0.00235 2.68125 4.0588 -0.0037 4.0625
14 (1±6%)x896 (1±6%)x224 2.8902 0.0027 2.8875 4.3789 0.0039 4.375
15 (1±6%)x960 (1±6%)x240 3.1092 0.01545 3.09375 4.7107 0.0232 4.6875

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

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AD Keypad

AD Keypad

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