STOP mode using

[rachny]

Posted on February 16, 2006 at 11:26

STOP mode using

[rachny]

Posted on February 15, 2006 at 12:21

Hi!

My question is: how to enter STOP-mode with low current (by datasheet 100uA)? Which internal clocks and peripherial block have to disable to reach this minimum current?

In the hardware I use CAN-module and the micom has to wake-up any CAN communication (XTI).

The main oscillator is always working, so on the CK pin always present the clock. Depends on the consumption from this clock?

Thanks.

[anis]

Posted on February 15, 2006 at 14:10

Hi Rachny,

The lowest STOP mode current could be obtained by:

-stopping the oscillator CK clock during STOP mode

-Puting the FLASH in Power down mode during STOP

-Disabling the Main Voltage Regulator

-stopping all not needed peripheral clocks

*But note that to wake up from stop mode you need the CK clock present so if your external hardware could reenable the oscillator when exiting from stop, then it's OK

But if this is not possible , then you should use the LPWFI mode which has power consumption not far from STOP mode and in this mode you do not need the external oscillator to wake up the MCU.

I advice you to take a look at application note AN2100.

STARM

;)

[rachny]

Posted on February 16, 2006 at 09:07

Thanks STARM!

:)

The setting was succesful, but the current consumption of the STR712 is about 1mA. I don't use RTC clock, the external clock is disabled by a external hardware during stop mode. The wake-up is working correctly via CAN-BUS. There is no other direct connection to the STR than the CAN transceiver IC & the JTAG pullup resistors.

How can I reduce the current about 100uA?

I set the peripherial clock gating (APBn_CKDIS), so only CAN is enabled, flash is in power down (FLASH_CR0->PWD = 1), MVR is disabled (PCU_PWRCR->LPVRWFI = 1). BSPIO, ADC (PCU_BOOTCR) are disabled.

What kind of further internal setting could be apply to reduce the consumption? Maybe the current of the CAN module is so high?

What about APBn_SWRES register?

Thanks.

Rachny

[anis]

Posted on February 16, 2006 at 10:03

Hi Rachny,

Have you also disabled the PLL2 and unsed clocks?

PCU->PLL2CR|=0x0007; // stop the PLL2

RCCU->PER &=~0x001F; // stop unused clocks

STARM

[rachny]

Posted on February 16, 2006 at 11:26

:p Thanks STARM!!!!!!! :p

The unused clocks was OK.

That's great!

The PCU->PLL2CR|=0x0007; // stop the PLL2 missed.

Now the Stop mode current is ~100uA.

Thanks!

Rachny

:-]

;)