MSP430FR5969: Current consumption does not decrease as much as data sheet

Hi Uchida,

When taking energy trace measurements, ensure the device is in free running mode when the debugger is attached. Also, it is sometimes difficult to see the datasheet specified current levels on a launchpad because of the other components on the board that can be drawing power.

I'll also point you to our application report MSP430™ Advanced Power Optimizations: ULP Advisor™ Software and EnergyTrace™ Technology for more information on achieving low power and using energy trace. Let me know if you have any further questions.

Best regards,

Caleb Overbay

Hi Caleb Overbay,

Thank you for your reply.

Using the same code, when measuring with a digital multimeter on a free run Launchpad, the current consumption has decreased.

I understood that when using EnergyTrace which requires CCS debugger connection, current consumption appears to be larger than usual.

Can I ask additional two questions?

1. When the following sample code is measured at 3 V in the free run state using Launchpad, the current consumption is 252.1 uA, and a value different from the data sheet is visible.

   Are there any possible causes?

   I use a sample code where the cache hit ratio is 0% described in SLAA526.

   However, the current consumption value when the cache hit ratio at 1MHz is 0% as described table 5.4 in the data sheet is 370 uA, which is larger than the  measured value.

#include <msp430.h>

void activeModeTest(void);

int main(void)
{
WDTCTL = WDTPW | WDTHOLD; // Stop WDT

P1DIR = 0;
P1OUT = 0;
P1REN = 0xFF;

P2DIR = 0;
P2OUT = 0;
P2REN = 0xFF;

P3DIR = 0;
P3OUT = 0;
P3REN = 0xFF;

P4DIR = 0;
P4OUT = 0;
P4REN = 0xFF;

PJDIR = 0xFF;
PJSEL0 = BIT4 | BIT5; // For XT1
PJOUT = 0;

// Disable the GPIO power-on default high-impedance mode to activate
// previously configured port settings
PM5CTL0 &= ~LOCKLPM5;

CSCTL0_H = CSKEY >> 8; // Unlock CS registers
CSCTL1 = DCOFSEL_0; // Set DCO to 1MHz
CSCTL2 = SELA__LFXTCLK | SELS__DCOCLK | SELM__DCOCLK;
CSCTL3 = DIVA__1 | DIVS__1 | DIVM__1; // Set all dividers to 1
CSCTL4 &= ~LFXTOFF; // Enable LFXT1
do
{
CSCTL5 &= ~LFXTOFFG; // Clear XT1 fault flag
SFRIFG1 &= ~OFIFG;
}while (SFRIFG1&OFIFG); // Test oscillator fault flag
CSCTL0_H = 0; // Lock CS registers

// Endless loop. Function never returns...
activeModeTest();
}

// This function executes the active mode power test.
void activeModeTest(void)
{
__asm("Main: \n"
" NOP \n"
" NOP \n"
" NOP \n"
"Label_A JMP Label_B ; cache miss \n"
" NOP \n"
" NOP \n"
" NOP \n"
" NOP \n"
" NOP \n"
" NOP \n"
"Label_B JMP Label_C ; cache miss \n"
" NOP \n"
" NOP \n"
" NOP \n"
" NOP \n"
" NOP \n"
" NOP \n"
"Label_C JMP Label_A ; cache miss \n"
" NOP \n"
" NOP \n"
" NOP ");
}

         As shown in the figure below, measurements were made by connecting an external power source of 3 V from the J 12 jumper and connecting a digital multimeter to the J 9 jumper.

2.Data sheet What percentage of cache hit ratio is the condition of IAM, FRAM_UNI (Unified memory) (3) in Table 5.4? Or if the device runs all the programs from FRAM, can I not use the cache?

Regards,

Uchida-k