Introduction: DIY Pocket Watch

In that busy world keeping a track of time is must for better carrying out and being a hobbyist why not make a twist to keep open a track of time. Thanks to engineering science there exist devices called 'watch' just! when you make things by yourself the pleasure is different, so in this Instructable I am going to she you how I successful this brief tiny watch.

Dance step 1: The Idea

The idea is to keep it as simple as possible and to use token components.

  1. A display to show time.
  2. A component to keep track of time.
  3. Another component part to take time and institutionalise it to display.
  4. And a power source.

// Flow sheet of estimate

Step 2: The Brainpower

The Brain should definitely Be a microcontroller as it has advantages of abundant programming and smaller size. At first I thought attiny85 would fit perfect but past it's limited GPIO pins made it difficult to procced with. then i decided to get going with Atmega328p available in tqfp package but having negligible experience in soldering such slender package I definite to go with arduino pro mini. Though this board is official retired but being open source they are still available.

Step 3: Display

A 0.91 inch OLED showing module would be nice choice for display, making it look more modern but then the problem is it's power consumption, on an intermediate IT consumes 20mA which would be hefty for battery. While wondering what to use as a display I found this DVD display laying around. This display has four digits of seven segment display with some complementary leds. All leds are configured in as general cathode so to drive them we necessitate to use method called mutliplexing which is nothing merely driving apiece digit one away one so fast that it looks all are lit up at same time. As wel Atmega328 can sink upto 20mA so the need of transistors is diminished. Each led works pretty satisfactory with 100 Georg Simon Ohm at 3.3v.

Tread 4: RTC

Arduino pro miniskirt pot keep track but problem with it is it's force consumption. At 3.3v it draws about 3mA at 8MHz and plus we also have display which bequeath also consume some of succus. I opt to collocate with DS3231 RTC buffalo chip Eastern Samoa it is easy to utilisation thanks to information technology's I2C port. Too it keeps rails of time more accurately than atmega328 and even consumes less power.

Step 5: Port With User

Interface is simple - user wants prison term, device gives it for this we could have used complex stuff like hand gesture or as simple as a push button. So whenever user wants to know the time, labor the button and meter is been displayed on the video display. The plan for the cypher was to detect if button is ironed, when ironed quest live time from RTC and show it through with display then again I realised that arduino professional mini has a push button to reset itself then why not use it so instead of checking up for button just take current time and display once and wait till next reset.

Step 6: The Twist

So directly we have our components set arduino pro min, Videodisk display, DS3231 RTC chip and CR2032 button cell as power house with non so much thinking over the choice of battery. So with circuit in my intellect I designed the PCB layout. And just before I could plac PCB peerless thing stroke my mind ... if I consider RTC chip and release prison cell holder and so they are already soldered in DS3231 RTC module then why waste resources in getting a custom PCB in point of fact in this case we just have solder power, I2C lines and the DVD display to pro mini. In case you want to get a load at PCB layout it is attached below.

Footfall 7: Problem With Button Cell

The mistake I ready-made aside not giving time to choose battery type paid it's price. When the device was powered through arduino uno as I used it to program arduino pro mini information technology worked floury only when information technology was being powered by button cell information technology behaved weirdly. After spending much time in finding retired what the job was - it was really that CR2032 can provide current upto 2mA and the requisite of device was much than that so sooner or later I ended up using a lipo shelling instead.

Step 8: The Code

The code Crataegus oxycantha look long and repetitive but is actually oblanceolate to understand. Everything is put into setup section as we do things only once and waiting until next reset command.

Catamenia of code is initialize everything -> take current clip from RTC -> manipulate the data so that that it can used to multiple the display digits -> and then show the data (time) for 2 seconds by multiplexing to each one digit one by one.

Step 9: Done !

I would throw 3D written a case for it just without a case it looks great A all components are exposed.

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