Introduction

This ADKey board with 10 keys can be used to drive your DFPlayer Pro, DFPlayer Mini, or Voice Recorder Module without programming or using various resistors. It offers 20 delicate key caps with comfortable hand feel, easy to be integrated in projects. You can also connect your favorite keys to the board through the welding pad on both sides. In addition, this ADkey board can be used as the ADkey input of a main-controller, by which it could expand 10 keys for your main-board via only one analog port.

Application

Specification

Board Overview

Board Overview

Key Series Resistance Key Series Resistance
K0 0R K1 3K
K2 6.2K K3 9.1K
K4 15K K5 24K
K6 33K K7 51K
K8 100K K9 220K

Schematics

Schematics

Tutorial

warning_yellow.png NOTE: When using this board to drive modules like DFPlayer Pro, DFPlayer Mini or Voice Recorder module, please do not connect VCC to the board since these modules have been pulled up 22K internally.

Requirements

Connection Diagram

Connection

Sample Code 1-Read Data

Press down a key, serial print a value.

#define ADPIN A0      //Read Pin

void setup() {
  Serial.begin(115200);
}

void loop() {
  // read the value from the sensor:
  Serial.println(analogRead(ADPIN));
  delay(10);
}

Expected Results

Result 1

Sample Code 2-Read Key Value

Press a key on the board, serial print the corresponding key value.

#define RESOLUTION 10   //ADC resoltuion
#define MAXVALUE pow(2,RESOLUTION)  //Resolution corresponding value 
#define PRECISION 10   //Admissible error 
#define ADPIN A0      //Read pin 

uint32_t ADKeyVal[10] = {0};   //Corresponding key value 
uint32_t ADCKeyIn = 0;


void setup() {
  Serial.begin(115200);
  ADKeybegin();
}

void loop() {
  ADCKeyIn = analogRead(ADPIN);
  if(ADCKeyIn < (MAXVALUE-PRECISION)){
    Serial.print("K = ");
    Serial.println(getKey());
  }
  delay(10);
}


void ADKeybegin(){
  float RESValue[10] = {0, 3, 6.2, 9.1, 15, 24, 33, 51, 100, 220};  //Resistor resistance 
  for(uint8_t i = 0; i < 10; i++){
    ADKeyVal[i] = RESValue[i]/(RESValue[i]+22)*MAXVALUE;
  }
}

int8_t getKey(){
  for(uint8_t i = 0; i < 10;i++){
    if(ADCKeyIn > ADKeyVal[i]){
      if((ADCKeyIn - ADKeyVal[i]) < PRECISION){
        return i;
      }
    } else{
      if((ADKeyVal[i] - ADCKeyIn) < PRECISION){
        return i;
      }
    }
  }
  return -1;
}

Expected Results

Result 2

Connection with DFPlayer Pro

Key Series Resistance Tap Long-press
K0 0R Pause & Play
K1 3K Last Volume+
K2 6.2K Next Volume-
K3 9.1K Playback mode switch
K4 15K Fast Forward 10s
K5 24K Pause & Play Next
K6 33K Volume- Volume-
K7 51K Volume+ Volume+
K8 100K Fast Backward 10s
K9 220K Play the first song, set volume to 10

Connection with DFPlayer Pro

Connection with DFPlayer Mini

Left:

Key Series Resistance Tap Long-press
K0 0R First song
K1 3K Second song
K2 6.2K Third song
K3 9.1K Fourth song
K4 15K Last Volume+
K5 24K Next Volume-
K6 33K Pause & Play Volume-
K7 51K Repeat all
K8 100K U/SD/SPI
K9 220K Playback mode

Right:

Key Series Resistance Tap Long-press
K0 0R Fifth song
K1 3K Sixth song
K2 6.2K Seventh song
K3 9.1K Eighth song
K4 15K Ninth
K5 24K Tenth
K6 33K Eleventh
K7 51K Twelveth
K8 100K Thirteenth
K9 220K Fourteenth

Connection with DFPlayer Mini

Connection with Voice Recorder Module

Key Series Resistance Tap Long-press
K0 0R Pause & Play
K1 3K Last Volume+
K2 6.2K Next Volume-
K3 9.1K Playback mode switch
K4 15K REC
K5 24K PLAY
K6 33K Volume- Volume-
K7 51K Volume+ Volume+
K8 100K Working mode switch
K9 220K Delete currently playing file

Connection with Voice Recorder Module

FAQ

For any questions, advice or cool ideas to share, please visit the DFRobot Forum.

More Documents

DFshopping_car1.png Get ADKey Board 10Keys from DFRobot Store or DFRobot Distributor.

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