This is more of a theoretical question, as I have enough battery not to go THAT ulp. However, I am learning, and my battery power might change, so..
(and I am sorry if this is a noob question; I probably could have calculated it myself, but I am having brain overflow).
My gadget is going to sleep most of the time. Even when awake, it's never used heavily, and I don't mind long wake-up times either. I do care about low power.
Currently, I am responding to button presses inside my loop(). I am working on interrupting on button presses instead, to save energy. And then I am beginning to get confused with energy consumption of various gadgets: MSP430 in different sleep modes, crystal should I have one (undecided about that now; probably so if I end up using UART); and now I found out that, in Energia at least, you can't interrupt by an INPUT pin, only INPUT_PULLUP - is that right? Is that a imitation of Energia or MSP430?
If I understand correclty, INPUT_PULLUP consumes power continuously, whether my button is pressed on not (do I add a resistor parallel to my button?) How much power, is unclear to me.
The manual says:
LaunchPad pins can be configured as INPUT_PULLUP. Often it is useful to steer an input pin to a known state if no input is present. This can be done by adding a pullup resistor (to ~3V), or a pulldown resistor (resistor to ground) on the input, with 10K being a common value. There are also convenient pullup resistors built into the LaunchPad that can be accessed from software. These built-in pullup resistors are accessed in the following manner.
3.3V / 10,000 Ohm = 33 microamp, bearable to my use case. What's the maximal resistance that is feasible on INPUT_PULLUP?
Maybe it would save me power NOT to go into deep sleep, if it means not having crystal, not having interrupts, just waking up on timer, say, 10 times per sec, just to check a button, and then stay awake for a few seconds? Seems counterintuitive.. just thought I'd check.