MSP430FR5730: How to reduce power consumption in LPM4

Gerd Christian Knese13

Intellectual 410 points

Part Number: MSP430FR5730

Hello,

I try to further reduce the power consumption in LPM4 in my MSP430FR5730 design.

I can't use LPM4.5, because the wake up source is Timer A0 clocked from an external ultra low power oscillator.

At the moment, I'm using the slac491i example for LPM4:

  P1DIR = 0; 
  P1OUT = 0; 
  P1REN = 0xFF;
  
  P2DIR = 0; 
  P2OUT = 0; 
  P2REN = 0xFF;
  
  CSCTL0_H = 0xA5;
  CSCTL1 |= DCOFSEL0 + DCOFSEL1;             // Set max. DCO setting
  CSCTL2 = SELA_1 + SELS_3 + SELM_3;        // set ACLK = VLO; MCLK = DCO
  CSCTL3 = DIVA_0 + DIVS_1 + DIVM_1;        // set all dividers 
  
  CSCTL4 = XT1OFF + XT2OFF;
  CSCTL5 &= ~(XT1OFFG + XT2OFFG);
  
  REFCTL0 |= REFTCOFF; 
  REFCTL0 &= ~REFON;

  __bis_SR_register(LPM4_bits);

Is there a clever way to save more power?

Kind regards

Gerd

over 5 years ago

0 Mike Tooma over 5 years ago

Genius 3255 points

General considerations for low power:
* All clocks (including MCLK) should be set to the lowest possible frequency.
* All unused modules should be turned off.
* All unused I/Os should be put to output direction with low output.

I hope this will help.

0 Gerd Christian Knese13 over 5 years ago in reply to Mike Tooma

Intellectual 410 points

Hi Mike,

Thanks a lot.

I'll try that.

In the mean time I found the major problem in my code.

Because of re-initialization of the ports in an other function unintentionally I created floating inputs.

I was not aware, that this can easy double the power consumption.

Kind regards
Gerd

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MSP430FR5730: How to reduce power consumption in LPM4