Trying to get 4x4 pad to randomly blink off, then back on ag

Development Boards Arduino
1

Hello everyone.

I am new to the Arduino world, and have recently purchased a Sparkfun 4x4 LED keypad, controlled by an Arduino Mega 2560.

I would like to code it so that the LEDs randomly blink off, then back on again. Not one at a time, but have them completely random (so maybe as three to five or so blink off at the same time sometimes).

The code that I have to light them up is off of the Sparkfun tutorial page:

/******************************************************************************

red-only.ino

Byron Jacquot @ SparkFun Electronics

1/6/2015

Example to drive the red LEDs in the RGB button pad.

Exercise 1 in a series of 3.

https://learn.sparkfun.com/tutorials/bu … hrome-leds

Development environment specifics:

Developed in Arduino 1.6.5

For an Arduino Mega 2560

This code is released under the MIT License.

Distributed as-is; no warranty is given.

******************************************************************************/

//config variables

#define NUM_LED_COLUMNS (4)

#define NUM_LED_ROWS (4)

#define NUM_COLORS (1)

// Global variables

static bool LED_buffer[NUM_LED_COLUMNS][NUM_LED_ROWS];

static int32_t next_advance;

static uint8_t led_index;

static const uint8_t ledcolumnpins[NUM_LED_COLUMNS] = {42,43,44,45};

static const uint8_t colorpins[NUM_LED_ROWS] = {22,30,33,36};

static void setuppins()

{

uint8_t i;

// initialize all of the output pins

// LED column lines

for(i = 0; i < NUM_LED_COLUMNS; i++)

{

pinMode(ledcolumnpins*, OUTPUT);*
// with nothing selected by default
digitalWrite(ledcolumnpins, HIGH);
}
// LED row lines
for(i = 0; i < NUM_LED_ROWS; i++)
{
pinMode(colorpins, OUTPUT);
// with nothing driven by default
digitalWrite(colorpins, LOW);
}
}
static void scan()
{
static uint8_t current = 0;
uint8_t val;
uint8_t i, j;
// Select a column
digitalWrite(ledcolumnpins[current], LOW);
// write the row pins
for(i = 0; i < NUM_LED_ROWS; i++)
{
if(LED_buffer[current])
{
digitalWrite(colorpins, HIGH);
}
}
delay(1);
digitalWrite(ledcolumnpins[current], HIGH);
for(i = 0; i < NUM_LED_ROWS; i++)
{
digitalWrite(colorpins, LOW);
}
// Move on to the next column
current++;
if (current >= NUM_LED_COLUMNS)
{
current = 0;
}
}
void setup()
{
// put your setup code here, to run once:
Serial.begin(115200);
Serial.print(“Starting Setup…”);
// setup hardware
setuppins();
// init global variables
next_advance = millis() + 1000;
led_index = 0;
// Initialize the LED display array
for(uint8_t i = 0; i < NUM_LED_COLUMNS; i++)
{
for(uint8_t j = 0; j < NUM_LED_ROWS; j++)
{
LED_buffer[j] = false;
}
}
// Set the first LED in the buffer on
LED_buffer[0][0] = true;
Serial.println(“Setup Complete.”);
}
void loop()
{
// put your main code here, to run repeatedly:
scan();
if(millis() >= next_advance)
{
next_advance = millis()+1000;
LED_buffer[led_index/NUM_LED_COLUMNS][led_index%NUM_LED_COLUMNS] = false;
led_index++;
led_index %= (NUM_LED_COLUMNS * NUM_LED_ROWS);
LED_buffer[led_index/NUM_LED_COLUMNS][led_index%NUM_LED_COLUMNS] = true;
}
}
Any and all help would be much appreciated.
P.C.

2

Never used the keypad, but here is logic to turn LEDs randomly on or off at random times

// 16 LEDs in matrix
bool _led[] = {false,false,false,false,false,false,false,false,false,false,false,false,false,false,false,false};

void loop() 
{
    // Random time interval
    int until = random(5000);
    delay(until);
    // How many LEDs to change state (at least 1)
    int amount = random(1,16);
    // Which LEDs to change state  
    for (int i = 0; i < amount; i++)
    {      
        // Toggle random LED
        int which = random(16);
        _led[which-1] = _led[which-1] ? false : true;
        digitalWrite(which-1, _led[which-1]);
        char buffer[20];
        sprintf(buffer,"LED %d, state %d\n\n",which-1, _led[which-1]);
        Serial.println(buffer);
    }
}

Completely untested, but should work.