IC for timer clock (hours)

Other Hardware LEDs and Multiplexing
1

Hi

I'm looking for an IC, which I could use to create a timer clock.
I need to do an endless cycle similar to on (4h), off (10 min), on (4h), off (10 min)...
Can anyone point me in a direction? I read that the timer 555 is not suitable for such long times.

Thanks for your help.

2

Do you want the cycle to start as soon as the circuit is powered up, or will it be at a certain times of the day?

3

An ATtiny85 is also an 8 pin DIP, and with the following sketch uploaded, will do as you've asked.

const byte output = 4;  // PB4, ATtiny pin 3

const unsigned long second = 1000UL;
const unsigned long minute = 60UL * second;
const unsigned long hour = 60UL * minute;

const unsigned long onTime  = 4 * hour;
const unsigned long offTime = 10 * minute;

void setup() {
   pinMode(output, OUTPUT);
}

void loop() {
   digitalWrite(output, HIGH);
   delay(onTime);
   digitalWrite(output, LOW);
   delay(offTime);
}

You could of course use an ATmega328P, Uno, Nano, etc., etc.

4

Not sure what you are trying to do. Are you are just looking for a programmable timer something like these.
https://www.amazon.com/s?k=programmable+timer
Or are you looking to build something as a project?

5

What about MCU, like some arduino? If local real time doesn't matter, that's easy alternative to 555. If you need to know certain time of the day, you want battery backed RTC module or MCU that can get the time from internet or from GPS.

6

Yes, of course I could use a MC, but I hoped there would be something cheaper which you don‘t need to program first. In my mind I have a few ideas for lighting projects, but I would need a easy solution (maybe a 20x20mm PCB).

7

Would you care to take a look at #2?

8

You asked for an IC.

You were given an IC.

You then moved the goalposts.

Good luck with your project. I'm done here.

9

Please explain how such a thing will "know" the on and off times.

Why are you asking this question on the Arduino forum?

10

@van_der_decken solution is around a buck for 1. The code is there so no code to write. If you want to do it with discrete chips you will need several.

11

I thought you could set the values with resistors. But ok, I see, it is probably easier to use a MC such as ATtiny85.

So far I have only used Arduino boards, but never a MC alone. How can I program it easily? What could I do for higher quantities? Does JLCPCB or PCBWAY offer some service for programming in higher quantities?

Ah, and it is ok if it starts right after powering up, without any delay!

12

It's not that difficult to design a PCB, but if you're going mass production, cost is obviously prio no 1. I'm not sure if the PCB manufacturers offer programming, but since they offer all sorts of services nowadays I wouldn't be surprised if they can do that as well. Otherwise you need a way to connect to the board in order to interface with the MCU.

With that requirement only an MCU is needed. Btw, how much drift is ok for those 4 h / 10 min?

13

The drift is not critical. Some minutes deviation ar no problem

14

Then you will be just fine with the internal clock at 1 or 8 MHz, it will keep cost down as well.

With an ATTiny, ceramic capacitor rated 0.1 u or similar, breadboard and some jumper wires you can start prototype, and you already got a suggestion for the code.

Uploading the code will be different than how you normally do, you need a programmer. A regular Arduino Uno / Nano for example can be used as such.

15

No. See post #4.