Low Power micro controller?

Hello i was wondering what board consumes the least amount of power with i2c? I'm trying to build my own digital watch and looking for a low energy so Lipo battery can last? i know i can put it into sleep mode with timers and whatnot. But trying to see what micro controller i can use? Can someone please help me out to figure which board i can use?

If you want something energy saver then you dont want a board, you want a bare bone microcontroller. Boards use power regulator and they waste energy. You should get an attiny or an atmega328p if you need more IO.

Hello thank you.

Thought: Scan what is available via Google Images and pick something that you would like as a starting point.


Thank you i looked at a lot of watches online but i like the one I'm going to make instead of numbers they will be characters letters something nice with a white oled screen in big letters :) but you are right they are very nice watches i always dream of having one for my self.

What about a low power display?

Hello i was thinking of of a Oled

I think you will find that an OLED draws a lot more current than an AVR processor.

Then what display would be good but it won't cost a lot?

Something LCD based I would think.

Maybe a bubble display with momentary push button to turn on the seven segments for two seconds. https://www.sparkfun.com/products/12710


Hello Actually you are right a lcd would be good i could use a Nokia 5110 LCD without the back light on it.

a bubble display would be nice too i haven't thought about that good point.

Bubble - Crossroads has a SPI version available or you could do your own.

It depends on the design requirements for your watch. What does it need to display? What physical size will it be? What battery life?

Well i would like to have a lcd or a oled i would like to display characters on the screen. i was at the start of all this i was thinking of using a bubble display. but then i thought after this to use a lcd to get a some cool characters for the clock instead of numbers only. So not sure yet. The lcd doesn't really need to be on all the time. a push button can be placed on the clock to wake up the lcd

josephchrzempiec: The lcd doesn't really need to be on all the time. a push button can be placed on the clock to wake up the lcd

If the display is off most of the time maybe it doesn't matter that much. I clicked on that google link above and then looked at one of the OLED watch projects. The author of that watch said its battery life was 1 year -- if only used 1 minute per day. I thought that was funny.

well i figure that much the battery won’t last more then a year. and i figure i would have to charge it. at least once a week And that is okay with me. and looking at everything still not sure if want to use a attiny85 chip sense i can run i2c on it and same with the attiny84 chip or the 328p chip. or who know’s what chip to use at this moment.

I have a $10 watch that a friend gave me in June 2007. It was used when he gave it to me. The display is always on. I have never replaced the battery and it is still running in 2015.

As for power usage, I believe the ATtinys and 328p use the same current. The non-picopower versions use a little bit more. The main difference is in voltage, clock frequency and time spent active versus asleep.

Yup 10 dollar watches last a long time but sense this will be digital with a little more processing . so trying to keep is as low power as i can. i know it will take a lot of power but only thing I'm unsure of is what Lcd or Oled to use?