Blinking LED Countdown Timer

Other Hardware LEDs and Multiplexing
1

Hello,

I wanted to make a group of 5 LED's blink simultaneously with a delay Then turn off for a period of time. After running the loop say 20 times, they would increase the speed at which they blink, and decrease the number of blinking LED's from 5 to 4. The effect I was looking to accomplish is a timer that blinks more rapidly as the number of LED's decreases. I started playing with the following code, and can get all 5 to blink simultaneously, but I am looking for the best way to change the blink rate to be short and shorter (Faster) as it progresses and additional LED's go out.

INO FILE

// Multi_Blink
//
// Blink 5 LED's at a given speed, then reduce the number to 4 LED's and blink faster, then 3, then 2, then 1.
// TODO; Add Piezo Speaker Sound as well




#include "Multi_Blink1.h"  // type definitions

const int blink1 = 1000;
const int blink2 = 800;
const int blink3 = 600;
const int blink4 = 400;
const int blink5 = 200;




// Blink Table T - Modify this table to suit whatever the output requirements are 
// Add or delete lines as required to achieve the desired effects.
//
ledTable  T[] =
//Pin  St   State 0      State 1  LastTime
{ 
  { 3, 1, {{HIGH, blink1}, {LOW, blink1}}, 0 },
  { 4, 1, {{HIGH, blink1}, {LOW, blink1}}, 0 },
  { 5, 1, {{HIGH, blink1}, {LOW, blink1}}, 0 },
  { 6, 1, {{HIGH, blink1}, {LOW, blink1}}, 0 },
  { 7, 1, {{HIGH, blink1}, {LOW, blink1}}, 0 },
  
};

// Self adjusting constants for loop indexes
#define  MAX_STATE  (sizeof(T[0].state)/sizeof(stateDef))
#define  MAX_LED    (sizeof(T)/sizeof(ledTable))

int pin = 11;

void setup()
{
  pinMode(pin, OUTPUT);
  for (int i=0; i < MAX_LED; i++)
  {
    pinMode(T[i].ledPin, OUTPUT);
    
    T[i].lastTransTime = millis();
    digitalWrite(T[i].ledPin, T[i].state[T[i].currentState].activeVal);
  }
}

void loop()
{
  for (int i=0; i < MAX_LED; i++)
  {
    // check if the state active time has expired (ie, it is less than current time)
    if (millis() >= T[i].lastTransTime + T[i].state[T[i].currentState].activeTime)
    {
      // switch to the next state with wrapround
      T[i].currentState = (T[i].currentState + 1) % MAX_STATE;
      
      // write out the next state value
      T[i].lastTransTime = millis();
      digitalWrite(T[i].ledPin, T[i].state[T[i].currentState].activeVal);
      tone(pin, 261, 1000);
    }
  }
}

HEADER FILE

// Multi_Blink.h
//
// Blink lots of LEDs at diffreent frequencies simultaneously
//
// Header file is required to be able to define the structured types
//
#include <Arduino.h>

#ifndef  MULTIBLINKH
#define  MULTIBLINKH

typedef struct
{
  uint8_t  activeVal;     // digital value for this state to be active (HIGH/LOW)
  uint16_t activeTime;    // time to stay active in this state stay in milliseconds 
} stateDef;

typedef struct
{
  uint8_t  ledPin;         // Arduino I/O pin number
  uint8_t  currentState;   // current active state
  stateDef state[2];       // the ON and OFF state definitions. Add more states if required
  uint32_t lastTransTime;  // the 'time' of the last state transition - saves the millis() value
} ledTable;

#endif
2

Are you using this as an exercise in learning use of structs? Because otherwise it seems a very convoluted way of implementing a very simple task!

Will the LEDs always blink in step?

Is there a reason not to use delay() in this code?

3

I was trying not to use delay, mostly because eventually I am going to add a buzzer sound. I am working on a prop project and want it like a beeping count down timer for a detonator.

If there is a better way to do this let me know.

4

What about my second question?