Low power usage with STM32F0

[superdrej]

Posted on October 27, 2014 at 20:45

Hi!

I am trying to find some pointers in designing a very simple low power application with STM32F0. Basically I need the system to be powered from a battery (probably 2xAA) and I need as long lifetime as possible. My application basically consists of a button a sensor and some communication interface (Bluetooth LE). The communication interface isn't really the problem here and neither is the sensor. Together they consume about 500uA. So when the user pressed the button I need the system to wake up, do some calculations and send the data trough the interface. I am planning on using stm32f051k8t6 as my MCU and I am using stm32f0 discovery for debugging and construction. My main question is this - how can I ensure that my system will use as little power as possible. And how long can I expect the system to run using 2xAA batteries? And the most important one - how do I get the system to wake up when the user presses that button? Also - how about oscillator choice when using different power saving modes? Can I use HSI or should I go for HSE? I have never worked with low power systems before so these things are a bit new to me. I've worked with STM32F4 before but I never uses any of its power saving features.

[chen]

Posted on October 28, 2014 at 10:29

Hi

''how can I ensure that my system will use as little power as possible.'' Use one of the 'low power'' modes of the processor - Sleep, Stop or Standby I recommend Sleep mode because it is the simplest to work with, it simply 'pauses' the processor on a command (WFI or WFE) ''And how long can I expect the system to run using 2xAA batteries?'' You will have to check the Data Sheet for the particular processor you are using. It will have tables giving the mA use for different clock speeds. You should be able to get an approximate answer from these tables. ''how do I get the system to wake up when the user presses that button?'' WFI - is Wait for Interrupt. So make the button an EXTI interrupt. ''how about oscillator choice when using different power saving modes? Can I use HSI or should I go for HSE?'' Please check you data sheet and reference manual. I think the low power modes will only work properly with HSE.