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STM32F407VG: Reduce power consumption by disabling ports clock

Question asked by sade.yonatan on May 4, 2016
Latest reply on May 5, 2016 by FTITI.Walid
Hi all.
I am trying to reduce power consumption in my device by disabling the GPIOs ports  clocks.
I did it by writing '0' in the RCC_AHB1ENR register at the required locations.
However, It did not work...
Then, I did a little experiment:
at the start of the main() I added these lines:

    RCC->AHB1ENR |= XX;
    while(1)
    {
    }

and measured the power consumption.
I got these unexpected results:
when XX = 0 I get 52.1 mA (Assume that the PCB consume some of the power)
         XX = 1 I get 64.5 mA (port A itself consume 12 mA???)
         XX = 3 I get 64.5 mA (nothing??)
         XX = 7 I get 64.7 mA (?)
         XX = F I get 64.7 mA (?)
         XX = 1F I get 63.8 mA (port E produce power? nobel prize...)
         XX = 3F I get 65.7 mA
         XX = FF I get 66.1 mA
         XX = 1FF I get 54.3 mA (All the ports together consume less???)
I am really confused...
Am I doing mistake?
Thank in advance for every reply...
Yonatan Sade

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