CC2652RB: Does timer block power policy?

Hi Matt,

You should be able to enter device sleep states in between servicing a timer interrupt.  Please review the timerled example and TI Driver Runtime APIs.  Are you evaluating with a LP-CC2652RB and how are you measuring the current consumption?

Regards,
Ryan

Hi Ryan, I'm actually programming a standalone PCB, so my ammeter is inline with the battery itself. I just re-tested and get the same behavior if I replace the last while() loop with a return(NULL) as done in timerled, but that's the only thing I see that is different. Again, if I use Task_sleep in that while loop without the timer, everything sleeps just fine, and I can toggle an LED in there instead of the timer callback. My timer is configured the same in Sysconfig to timerled.

By "same behavior" do you mean expected power consumption or over-consumption?  What is the power consumption when operating timerled out-of-box?  Have you reviewed the Timer and Power APIs?

Regards,
Ryan

To achieve the lowest power with timerled I have to modify SysConfig to use LF RCOSC and use a while loop with Task_sleep (see modification below). The same problem exists, the timer works but doesn't achieve sleep in between GPIO_toggle. There's nothing to indicate in the API why I wouldn't achieve sleep, and my expectation was the same as yours (it should work): is it possible that the timer is forcing use of LF XOSC? With would force the main resonator to remain on and may be a source of the ~0.8mA I'm seeing.

/*
 *  ======== timerled.c ========
 */

#include <stddef.h>

/* Driver Header files */
#include <ti/drivers/GPIO.h>
#include <ti/drivers/Timer.h>
#include <ti/sysbios/knl/Task.h>

/* Board Header file */
#include "ti_drivers_config.h"

/* Callback used for toggling the LED. */
void timerCallback(Timer_Handle myHandle, int_fast16_t status);

/*
 *  ======== mainThread ========
 */
void* mainThread(void *arg0) {
	Timer_Handle timer0;
	Timer_Params params;

	/* Call driver init functions */
	GPIO_init();
	Timer_init();

	/* Configure the LED pin */
	GPIO_setConfig(LED_0, GPIO_CFG_OUT_STD | GPIO_CFG_OUT_LOW);

	/* Turn off user LED */
	GPIO_write(LED_0, CONFIG_GPIO_LED_OFF);

	/*
	 * Setting up the timer in continuous callback mode that calls the callback
	 * function every 1,000,000 microseconds, or 1 second.
	 */
	Timer_Params_init(&params);
	params.period = 1000000;
	params.periodUnits = Timer_PERIOD_US;
	params.timerMode = Timer_CONTINUOUS_CALLBACK;
	params.timerCallback = timerCallback;

//	timer0 = Timer_open(CONFIG_TIMER_0, &params);
//	if (timer0 == NULL) {
//		/* Failed to initialized timer */
//		while (1) {
//		}
//	}
//
//	if (Timer_start(timer0) == Timer_STATUS_ERROR) {
//		/* Failed to start timer */
//		while (1) {
//		}
//	}

//	return(NULL);

	while(1) {
		Task_sleep(100000);
		GPIO_toggle(LED_0);
	}
}

/*
 * This callback is called every 1,000,000 microseconds, or 1 second. Because
 * the LED is toggled each time this function is called, the LED will blink at
 * a rate of once every 2 seconds.
 */
void timerCallback(Timer_Handle myHandle, int_fast16_t status) {
	GPIO_toggle(LED_0);
}

As you can see from the table in Section 5.5 (Power Consumption - Power Modes) of the Datasheet, the difference in power consumption between XOSC_LF and RCOSC_LF is a matter of 0.1 µA.  Both are also available in standby mode (Table 6-1).  What happens when you leave SysConfig at the LF XOSC source setting?

Regards,
Ryan

These two measures are the code above (Task_sleep in while loop), LED off, only difference is XOSC_LF vs. RCOSC_LF. That said, using RCOSC_LF with the timer doesn't 'fix' anything—LED off current with RCOSC_LF using the timer is 0.84mA.

Hi Matt,

Please refer to SWRA649 and SWRA499.  Do you know what the behavior is with the LP-CC2652RB which has an external LF crystal?

Regards,
Ryan

Ryan, refer to what parts? Is there something in there that resolves my issue (using Timer)? I don't know the behavior with the LP/external crystal. The point of using BAW for me is to reduce BOM.

All of SWRA649, I don't know, and apologies for my previous comment which was made without thinking through the device which is being used.  What is your SIMPLELINK-CC13X2-26X2-SDK version?

Regards,
Ryan

I don't see anything that would help me with this issue in SWRA649. I'm not migrating. I'm using LF RCOSC because it's low cost and low power. SDK simplelink_cc13x2_26x2_sdk_4_40_00_44. Thanks

Hey Matt,

I apologize for the confusion.  ~860 µA is expected when using the timer peripheral according to this E2E post, regardless of LFOSC source.  Z-Stack and others use util_timer which allows for standby mode operation.

Regards,
Ryan