Minimizing power consumption: what can be done?

[keepcoding]

Posted on September 27, 2013 at 16:54

Hi

I'm a bit confused with all the clocks and power saving options on the STM32F3 Discovery board.I'd like to minimize the power consumption by gating all unnecessary clocks and peripherals / memory.The MCU is in sleep mode and will wake up every 100 ms so do some calculations (~10ms). The GPIOA + B, DMA, SPI and RAM need to be enabled all the time (that's why I can't use stop mode). Are all unused peripherals disabled per default or do I need to disable everything manually?Which other clocks can I disable? Would it make sense to lower the system clock frequency? What else could I do to reduce the power consumption?Thanks in advance for any advice

[Tesla DeLorean]

Posted on September 27, 2013 at 17:04

Running slower will definitely help in most situations, as will spining in __WFI() idle loops. If you can run off HSE/HSI rather than the PLL that will also help. Try running code from RAM rather than FLASH.

Dropping speed will not help if it extends the power on time, you have to look at the current over time, so integrate. ST recommends putting unused pins in Analog mode as this also turns off the digital input (schmitt trigger). Other manufacturers recommend logic low outputs to stop pins oscillating. Turn off LEDs and external drivers where possible, often a lot of static current is drawn by external parts on boards, or through the pin drivers.