Blink LED without delay - arduino-uno

Question

So I'm creating a code so that I can read and store temperature values
for at least 8hours and store it in the Arduino EEPROM. I also want the Built in LED to flash once every second, while the temperature sensor records once every minute. I wrote the following but I'm left with the LED staying on for a whole minute then off for another minute and so on. I want it to keep constantly flashing. I know it's because of my delay(6000) but I don't know how to fix it. Any help is appreciated, thanks!
#include <EEPROM.h> //Librería para controlar la EEPROM de la Arduino
float tempC; //Initialize variable for storing Temperature
int tempPin = 0; //Conected at A0
int addr = 0; //Cantidad de espacios (bytes) iniciales
int count = 0; //counter needed to stop at a certain point before overflowing the EEPROM memory
int Voltages[501]; // Array with space for 501 data Points.A little over 8 hours. Holding integer values of Voltages.
float Temps[501]; //Holds float values for Temperatures
const int SWITCH = 8; //set switch to port 8
int ledState = LOW; // ledState used to set the LED
unsigned long previousMillis = 0; // will store last time LED was updated
const long interval = 1000; // blink once per second
void setup(){
Serial.begin(115200);
pinMode(LED_BUILTIN,OUTPUT);
pinMode(SWITCH,INPUT_PULLUP);}
void loop(){
int i;
if (digitalRead(SWITCH)==HIGH & count<=501){
for (int i=0;i<EEPROM.length();i++){
EEPROM.write(i,0);} // Clears the EEPROM so that only new recorded values are shown. In case of terminating before 8h
Serial.println("-------Recording-------");
unsigned long currentMillis = millis(); // current time
if (currentMillis - previousMillis >= interval) {
previousMillis = currentMillis; // save the last time the LED blinked
if (ledState == LOW) {// if the LED is off turn it on and vice-versa:
ledState = HIGH;} else {
ledState = LOW;}
digitalWrite(LED_BUILTIN, ledState);}
for (i=0; i<501; i++){
count = count+1;
int v = analogRead(tempPin); // reads voltage
Voltages[i] = v;
Serial.println(i);
Serial.println(Voltages[i]);
delay(60000);
EEPROM.put(addr, Voltages[i]); //stores voltages in EEPROM
addr= addr +2;}}

Answer 1

I think the solution you are looking for involves the use of timer interrupts. That would execute an interrupt service routine (might as well be a blinking led) regardless of what happens in the rest of your loop function. This might give you a better in-sight: Arduino timer interrupts