I just decide to make a very simple intervalometer, with easy inputs of parameters for the time lapse. The intervalometer uses two buttons (Enter and Select) and one potentiomenter (pot). With the buttons you can enter into the programming mode or start the time lapse shooting. With the pot you can specifiy (with some small error) the amount of seconds between shots and the total minutes of shooting.

There are several ways of selecting and calcualte the time lapse parameters. The one I propose here is just one of them.

After entering time interval and total time lapse shooting time, the program will calculate the total ammount of shots and will start taking shots, at the defined interval of seconds.

I have attached a program sketch for the Arduino in C. It is just a sketch. I am not a good programmer so you can take this as an idea and make a better version to suit your needs.

Supplies

Here are the materials I used in this project:

01 x Arduino Nano

01 x LCD 16x2 with PCF8574T (I2C)

01 x 4N35 general purpouse phototransistor optocoupler (you can use PC817 or other similar)

02 x swith buttons

01 x 10k potentiometer

02 x 10k resistors

Ohter: board, conectors, wires, USB cable.

Step 1: Assemble

I use a standard universal board for soldering all the components. Then I use terminals for mounting the Nano and avoid soldering directly on the pins. I also used an IC sockets for the phototransistor. Then soldered directly over the rest of the components.

I use wire wrap and copper wire. The display is mounted using breadboard separators with screws.

I use the power from the USB connector to the Nano while I was programming. After that, I decided to use a stand alone power supply, at 5V from an old cell phone. I just adapted the connector for pins. I powered the Nano using GND pin and the 5V pin.

Then I connected one end of pot resistor to GND and the other to 5V. The center is connected to A0 (analog input). The A0 input will read from 0V to 5V and will convert it to an integer value in the range 0 to 1023.

The button switches are connected to D3 and D4 in the Nano. Finally I used D13 as a digital output to the phototransistor.

I have an old Cannon SX-50HS, non DLSR, that uses a standard 2.5mm plug.

Step 2: The Circuit

The circuit is very simple. I used two DI as inputs (D3, D4), one analog input to read the value of the potentiomenter (from 0 to 1023) and one digital output to trigger the phototransistor (D13). The picture shows the basic schematic.

The I2C LCD is connected to GND and 5V. SDA and SCL from display are connected to the Arduino pins SDA(A4) and SCL(A5).

It can be improved in many ways and can be suited to your needs.

Step 3: The Program

I have attached a draft of the program.I used the libraries "Wire.h" and "LiquidCrystal_I2C.h" to handle the display.

The program is very simple and can be improved in many ways. It starts by defining variables, initializing inputs, output, the LCD and then prints a welcome message.

After that your need to input time between shots and total time of shooting. The you can press "select" button to modify time lapse parameters or "enter" to start shooting.

Step 4: Improvments

This project can be improved in many ways. The hardware is very simple. The potentiometer may help to enter parameters very ease, but sometimes the accuracy is not good. Depends on the quality of the potentiometer. You can replace by an enconder for example.
The phototransistor could be replace by any other device. The mounting of the components could be done more compact and inside an enclosure. You can also use other microcontroller that you have at hand.

This is just an easy project I made, because I needed to take some pictures and make a timelapse. I'm glad to share with the community so it can be improved and may help as inspiration for other projects.