This is not strictly an Arduino question. I've got an Arduino controller that is connected to another wirelessly via the NRF24l01 chips. The sending unit only needs to send a simple up/down signal to the Arduino, so using an Arduino for that is really overkill. I'd like the remote to have a very long battery life, preferably run on like a single CR2032 battery.
Anyone have any clever ideas of the easiest way to do this? Maybe use a lower power chip like the AT88 instead? I also need to send a simple serial number so the Arduino's get the signal from the correct remote control. I'd like the remote to be basically completely powered down except when the button is pushed in order to maximize battery life.
A bare bones Arduino using an ATMega328 will run for years on a battery if configured properly. See Gammon Forum : Electronics : Microprocessors : Power saving techniques for microprocessors
If all you need is one or two switches you can go really small, i have a nrf24l01 remote that only wake up on interrupt it takes around 3 ua sleeping, with that a CR2032 will last for many years.
I'm running mine on a attiny 13A so any 8pin+ attiny should be able to handle it easily.
I made this a year or so ago and the battery are still good, not the best looking thing i ever made but its good for testing.
Thanks for the great response!
Yes, there will just be two buttons. Basically an up and a down button. Doesn't get much simpler. But the other devices need to communicate with each other more regularly and more complex, thus the need for a microprocessor.
My concern was the wake up time on the arduino. I can't tolerate much delay on this, but it seems that is a non-issue. Using the AT328 certainly has some advantages because I can include a lot more robust encryption in the signal that I can't do with some dumb circuit. Sounds like I'll just go with a tiny arduino and be done with this.
So will the Arduino an NRF2401 run reliably on just a single 3V coin cell battery, or do I need two in series? I've got some 3.3v pro minis I'm going to try. And I've got a super tiny NRF board that I'll use.
Doing some experimenting with this, so not sure I'm measuring correctly.
I removed the led and regulator from a 3.3v pro mini. It still measures about 3ma power draw in run mode. Is that normal? I can't program it yet because I don't have the usb interface yet. So can't test in sleep mode.
Also, there are VCC and raw pin. My understanding is that raw is for inputting a higher voltage and go through regulator and VCC connects directly to the ATMega?
It still measures about 3ma power draw in run mode.
Yes. Power it through the Vcc pin.
DO READ this post on power saving -- it is very clear and packed with useful information.
You may also appreciate this solar/supercap powered Arduino project.
Thanks. I read through the post. Great information. Your comment about solar is interesting. On a device that gets used outdoors primarily, and with low power consumption, a tiny solar cell could probably eliminate the need for charging.