WFI in LowPowerMode

[smartpocket]

Posted on July 12, 2005 at 07:36

WFI in LowPowerMode

[smartpocket]

Posted on June 24, 2005 at 05:23

Hi to all.

I have a problem entering in LPWFI: the Main Voltage Regulator is alwais ON, even if bit LPVRWFI is set. I have made many tests with the same result: the power consumption is too much large!! For example: Standby (or powerdown) mode: 800 uA (ARM + rest of board - all PIO in HI) LPWFI: 2600 uA (ARM + rest of board - all PIO in HI) This is a source code: void MySuspend(void) { volatile u32 Tmp; // port in HighImpedence GPIO_Config(GPIO0, 0xFF, GPIO_HI_AIN_TRI); // GPIO_Config(GPIO1, 0xFF, GPIO_HI_AIN_TRI); // // Set LPM in WFI mode Tmp = RCCU->CLKCTL | 0x01; RCCU->CLKCTL = Tmp; // Select CK_AF in LPM Tmp = RCCU->CLKCTL | 0x02; RCCU->CLKCTL = Tmp; // Select 32KHz clock Tmp = RCCU->CLKCTL | 0x04; // bit 2 - CKAF_SEL RCCU->CLKCTL = Tmp; // switch off the PLL1 RCCU->PLLCONF &= ~RCCU_FREEN_Mask; // free running RCCU->PLLCONF |= 0x07; // stop PLL1 // Power OFF external 4MHz oscillator GPIO_Config(GPIO1, 0x08, GPIO_OUT_PP); // P1.3 -->> PushPull GPIO_BitWrite(GPIO1, 3, 0); // 4MHz Oscillator OFF // Power Menagement in WFI mode Tmp = 0x0010; // Main Voltage Regulator OFF in WFI Tmp &= ~PCU_LPRWFI_Mask; // Low Power Regulator ON in Wait-For-Interrupt mode. Tmp |= 0x0200; // Flash low-power (low-speed) mode select // Tmp |= 0x0040; // Activate Powerdown Mode PCU->PWRCTRL |= PCU_WREN_Mask; PCU->PWRCTRL |= Tmp; while (PCU->PWRCTRL & 0x4000); /*==============================*/ // Enter WFI Mode RCCU->SYSMODE &= ~0x0001; /*==============================*/ } Can someon help me ? Thanks smart :-[

[anis2]

Posted on June 24, 2005 at 15:23

Hi Smart,

Your suspend routine seems correct, but I don't think that the high power consumption is due to the MVR. To have lower power consumption , you have to power down the FLASH during LPWFI mode. To do this you have to add this instruction: FLASHR->CR0 |= 0x8000; // set bit PWD But to do this you must map the interrupt vectors and interrupt service routines in RAM (and remap it to 0x00h). You have to insert a 20µs software delay in the interrupt service routine before accessing any Flash location. Refer to the STR7x flash reference manual. Hope it helps Ciao! 8-)

[luciano]

Posted on July 12, 2005 at 06:37

Excuse me, Bouha, but I believed that when the micro is in LPWFI mode, Flash is automatically in power down. Isn't so?

Thanks L.

[anis2]

Posted on July 12, 2005 at 07:36

Hi Lucky74,

The Flash is not automaticaly turned in power down mode when going in LPWFI mode, you have to set PWD bit in the FLASH_CR0 register. Ciao 😉