I am trying to integrate a keypad to my project and wanted to test it in a simple program first. The keypad is connected to the Arduino Uno (ATmega328P) like this:
C1 -> Pin 6
C2 -> Pin 8
C3 -> Pin 4
R1 -> Pin 7
R2 -> Pin 2
R3 -> Pin 3
R4 -> Pin 5
I downloaded a template program for this keypad and adjusted the configuration of my pins accordingly.
Here is the code:
#include <LCD5110_Graph.h>
/* keyPadHiduino Example Code
by: Jim Lindblom
date: January 5, 2012
license: MIT license. If you find this code useful, please
feel free to use this code however you'd like, commercially
or otherwise. Just keep this license on there whatever you do.
This code implements a 12-key USB keypad. You can type 0-9,
* is the + sign and the # key is enter. I'm using SparkFun's
12-button keypad, your pinouts may vary. Multi-touch is
not supported.
SparkFun Keypad Pinout:
Rows and columns are connected as such:
-------------
R1 | 1 | 2 | 3 | - 7 (grün)
R2 | 4 | 5 | 6 | - 2 (braun)
R3 | 7 | 8 | 9 | - 3 (schwarz)
R4 | * | 0 | # | - 5 (violett)
-------------
|C1 |C2 |C3
6(blau) 8(gelb) 4(weiß)
*/
// Pins 1-7 of the keypad connected to the Arduino respectively:
uint8_t keypadPins[7] = {2, 3, 4, 5, 6, 7, 8};
int keypadStatus; // Used to monitor which buttons are pressed.
int timeout; // timeout variable used in loop
LCD5110 LCD(9, 10, 11, 12, 13);
extern uint8_t SmallFont[]; //charactersize 6x8 pixels
extern uint8_t TinyFont[]; //charactersize 4x6 pixels
extern uint8_t MediumNumbers[]; //charactersize 12x16 pixels
void setup()
{
LCD.InitLCD();
LCD.setFont(TinyFont);
for (uint8_t i=0; i<7; i++)
{
pinMode(keypadPins[i], INPUT); // Set all keypad pins as inputs
digitalWrite(keypadPins[i], HIGH); // pull all keypad pins high
}
keypadStatus = 0;
Serial.begin(9600);
}
void loop()
{
keypadStatus = getKeypadStatus(); // read which buttons are pressed
if (keypadStatus != 0) // If a button is pressed go into here
{
Serial.println("A button was pressed");
sendKeyPress(keypadStatus); // send the button over USB
timeout = 2000; // top of the repeat delay
while ((getKeypadStatus() == keypadStatus) && (--timeout)) // Decrement timeout and check if key is being held down
delayMicroseconds(1);
while (getKeypadStatus() == keypadStatus) // while the same button is held down
{
sendKeyPress(keypadStatus); // continue to send the button over USB
delay(50); // 50ms repeat rate
}
}
}
/* sendKeyPress(int key): This function sends a single key over USB
It requires an int, of which the 12 LSbs are used. Each bit in
key represents a single button on the keypad.
This function will only send a key press if a single button
is being pressed */
void sendKeyPress(int key)
{
switch(key)
{
case 1: // 0x001
LCD.clrScr();
LCD.print("1",CENTER,14);
LCD.update();
Serial.print('1'); // Sends a keyboard '1'
break;
case 2: // 0x002
LCD.clrScr();
LCD.print("2",CENTER,14);
LCD.update();
Serial.print('2');
break;
case 4: // 0x004
LCD.clrScr();
LCD.print("3",CENTER,14);
LCD.update();
Serial.print('3');
break;
case 8: // 0x008
LCD.clrScr();
LCD.print("4",CENTER,14);
LCD.update();
Serial.print('4');
break;
case 16: // 0x010
LCD.clrScr();
LCD.print("5",CENTER,14);
LCD.update();
Serial.print('5');
break;
case 32: // 0x020
LCD.clrScr();
LCD.print("6",CENTER,14);
LCD.update();
Serial.print('6');
break;
case 64: // 0x040
LCD.clrScr();
LCD.print("7",CENTER,14);
LCD.update();
Serial.print('7');
break;
case 128: // 0x080
LCD.clrScr();
LCD.print("8",CENTER,14);
LCD.update();
Serial.print('8');
break;
case 256: // 0x100
LCD.clrScr();
LCD.print("9",CENTER,14);
LCD.update();
Serial.print('9');
break;
case 512: // 0x200
LCD.clrScr();
LCD.print("Star",CENTER,14);
LCD.update();
Serial.print('*');
break;
case 1024: // 0x400
LCD.clrScr();
LCD.print("0",CENTER,14);
LCD.update();
Serial.print('0'); // Sends a keyboard '0'
break;
case 2048: // 0x800
LCD.clrScr();
LCD.print("Raute",CENTER,14);
LCD.update();
Serial.print('#'); // Sends the 'ENTER' key
break;
}
}
/* getKeypadStatus(): This function returns an int that represents
the status of the 12-button keypad. Only the 12 LSb's of the return
value hold any significange. Each bit represents the status of a single
key on the button pad. '1' is bit 0, '2' is bit 1, '3' is bit 2, ...,
'#' is bit 11.
This function doesn't work for multitouch.
*/
int getKeypadStatus()
{
uint8_t rowPins[6] = {keypadPins[5], keypadPins[0], keypadPins[1], keypadPins[2]}; // R1 = KeypadPin[5], R2 = ...
uint8_t columnPins[3] = {keypadPins[4], keypadPins[6], keypadPins[2]}; // C1 = KeypadPin[4], C2 = ...
int keypadStatus = 0; // this will be what's returned
/* initialize all pins, inputs w/ pull-ups */
for (uint8_t i=0; i<7; i++)
{
pinMode(keypadPins[i], INPUT);
digitalWrite(keypadPins[i], HIGH);
}
for (uint8_t row=0; row<4; row++)
{ // initial for loop to check all 4 rows
pinMode(rowPins[row], OUTPUT); // set the row pin as an output
digitalWrite(rowPins[row], LOW); // pull the row pins low
for (int col=0; col<3; col++)
{ // embedded for loop to check all 3 columns of each row
if (!digitalRead(columnPins[col]))
{
keypadStatus |= 1 << ((row+1)*3 + (col+1) - 4); // set the status bit of the keypad return value
Serial.print("keypadStatus: ");Serial.println(keypadStatus);
}
}
pinMode(rowPins[row], INPUT); // reset the row pin as an input
digitalWrite(rowPins[row], HIGH); // pull the row pin high
}
return keypadStatus;
}
To check if the pressed numbers gives back the correct value I print its value via serial communication to the arduino console and display it on my LCD.
My problem is that the moment I upload the code and the µcontroller starts running I get lot's of inputs from my keypad without touching anything, the value calculated in getKeypadStatus() is 2048" which translates to the "#" buttton. I tried to display the value keypadStatus whenever it was calculated and as a result I get tons of "2048" via serial communication.
furthermore I measured 5V at Pin 4 of the arduino. I switched some wires to check if the problem is on the keypad or arduino. When switching wires I still measured 5V on Pin 4 of arduino but and the value printed (keypadStatus) was still "2048".
The keypad itself can not be faulty as I measured the resistance for every button and it worked fine.
Does someone have advice?
Better use the Keypad library by Mark Stanley and Alexander Brevig. This library is responsible for setting up the pins and polling the different columns and rows. To install the Keypad library, go to Sketch > Include Library > Manage Libraries and search for "keypad". Click on the library and then click install. The code for a 3x4 keypad is as follows
#include <Keypad.h>
const byte ROWS = 4;
const byte COLS = 3;
char hexaKeys[ROWS][COLS] = {
{'1', '2', '3'},
{'4', '5', '6'},
{'7', '8', '9'},
{'*', '0', '#'}
};
byte rowPins[ROWS] = {7, 2, 3, 5};
byte colPins[COLS] = {6, 8, 4};
Keypad customKeypad = Keypad(makeKeymap(hexaKeys), rowPins, colPins, ROWS, COLS);
void setup(){
Serial.begin(9600);
}
void loop(){
char customKey = customKeypad.getKey();
if (customKey){
Serial.println(customKey);
}
}