QN908x and AN01786

[xaviervilajosan]

Hi,

I looked at the AN01786 and tried to reproduce the measurements. I followed all the steps as indicated in the document. To give further details:

1) using MCUXpresso in WIndows

2) SDK 2.2 Beta

3) user project: qn908xcdk_wireless_examples_bluetooth_power_profiling_freertos

4) added the symbol cQN_UsePowerDownMode in the project configuration.

I flashed the code in the board and executed while running the debugger. The button interaction seems correct and leds change color until the device starts advertising. 

Then I moved forward and stopped the debugger and tried to measure consumption. The first think I noticed is that after pressing 1 time the button number 1 the device stops to be responsive, i.e despite I press the button 100 times it does not execute the next step in the state machine (i.e changing led color to green, red, etc...)

I started digging into the code and some things are not working well.

1) the Code example says the application starts in PM1 but looking the hardware_init function it starts in sleep

#if (cQN_UsePowerDownMode)
SetGpioWakeupLevel(BOARD_SW_GPIO, BOARD_SW1_GPIO_PIN, 0U);
SetGpioWakeupLevel(BOARD_SW_GPIO, BOARD_SW2_GPIO_PIN, 0U);
PM_SetReq(kPmSleep, kPmReqUserPolicy); // kPmReqBle);kPmPowerDown0
#endif

looking at the state machine in the function 

void BleApp_HandleKeys(key_event_t events)

I can see that the correct Power Levels are set  

... e.g., 

PM_SetReq(kPmPowerDown0, kPmReqUserPolicy);

and I assume those are entered not at tha moment but when the Idle task is executed, when the 

PM_PowerManagement();

function is called

My feeling is that the GPIO state interrupts from the buttons are not stored/recovered after kPmPowerDown0 and hence the board cannot wake up from the sleep mode. I tried several things such as calling the function 

/* Reinitialize peripherals after waked up from PD, this function will be called in critical area */
void BOARD_WakeupRestore(void)
{
/* Enable FPU after sleep */
#if ((__FPU_PRESENT == 1) && (__FPU_USED == 1)) || (defined(__VFP_FP__) && !defined(__SOFTFP__))
SCB->CPACR |= 0x00f00000; /* set CP10, CP11 Full Access */
#endif

/* initialize all the GPIO pins for keyboard */
GPIO_SetFallingEdgeInterrupt(GPIOA , sw_pins_mask);
GPIO_EnableInterrupt(GPIOA, sw_pins_mask);
NVIC_EnableIRQ(GPIOA_IRQn);

}

in board.c. I looked what component is calling that function and nobody calls it in this example. (Maybe the PM_Management internally but I looked at the assembler code and it does not look so)

Can you please let me know what I am missing? I assume that if someone has done the AN01786 the used code should be available somewhere. 

I also did another test. I took the code in the qn908xcdk_demo_apps_power_mode_switch example application. In there I can see a simple state machine that according to the sleep mode executes the required actions. As the code works (because I tested and measured it) I assumed that would work too if I replace the

PM_PowerManagement() function call in the Idle task.

Hence my idle task looked like this now:

static void App_Idle(void)
{
//PM_PowerManagement();
power_mode_t status = getPowerModeStatus(); // gets the status set by the button handler function
switch (status)
{
case kPmActive:
break;
case kPmSleep:
CLOCK_DisableClock(kCLOCK_Flexcomm0);
POWER_EnterSleep();
CLOCK_EnableClock(kCLOCK_Flexcomm0);
break;
case kPmPowerDown0:
__disable_irq();
switch_to_OSC32M();
POWER_LatchIO();
CLOCK_DisableClock(kCLOCK_Flexcomm0);
POWER_EnterPowerDown(0);
CLOCK_EnableClock(kCLOCK_Flexcomm0);
POWER_RestoreIO();
switch_to_XTAL();
/* after waking up from pwoer down, usart config is lost, recover it */
BOARD_WakeupRestore();
__enable_irq();
break;
case kPmPowerDown1:
/* Enable GPIO wakeup */
NVIC_ClearPendingIRQ(EXT_GPIO_WAKEUP_IRQn);
NVIC_EnableIRQ(EXT_GPIO_WAKEUP_IRQn);
__disable_irq();
switch_to_OSC32M();
#if (defined(BOARD_XTAL1_CLK_HZ) && (BOARD_XTAL1_CLK_HZ == CLK_RCO_32KHZ))
POWER_WritePmuCtrl1(SYSCON, SYSCON_PMU_CTRL1_RCO32K_DIS_MASK, SYSCON_PMU_CTRL1_RCO32K_DIS(1U));
#elif(defined(BOARD_XTAL1_CLK_HZ) && (BOARD_XTAL1_CLK_HZ == CLK_XTAL_32KHZ))
POWER_WritePmuCtrl1(SYSCON, SYSCON_PMU_CTRL1_XTAL32K_DIS_MASK, SYSCON_PMU_CTRL1_XTAL32K_DIS(1U));
#endif
POWER_LatchIO();
POWER_EnterPowerDown(0);
POWER_RestoreIO();
switch_to_XTAL();

NVIC_DisableIRQ(EXT_GPIO_WAKEUP_IRQn);
NVIC_ClearPendingIRQ(EXT_GPIO_WAKEUP_IRQn);

#if (defined(BOARD_XTAL1_CLK_HZ) && (BOARD_XTAL1_CLK_HZ == CLK_RCO_32KHZ))
POWER_WritePmuCtrl1(SYSCON, SYSCON_PMU_CTRL1_RCO32K_DIS_MASK, SYSCON_PMU_CTRL1_RCO32K_DIS(0U));
#elif(defined(BOARD_XTAL1_CLK_HZ) && (BOARD_XTAL1_CLK_HZ == CLK_XTAL_32KHZ))
POWER_WritePmuCtrl1(SYSCON, SYSCON_PMU_CTRL1_XTAL32K_DIS_MASK, SYSCON_PMU_CTRL1_XTAL32K_DIS(0U));
#endif
/* after waking up from pwoer down, usart config is lost, recover it */
BOARD_WakeupRestore();
__enable_irq();
break;
default:
break;
}
}

I tested again, and the same happens. While with the debugger I can execute correctly the application (I assume that PM is not executed when SWD or JTAG are active) as soon as I stop the debugger the device stays in PM0 and cannot recover it. 

To reflash it I need to reset it right before the debugger starts as it stays in PM0 and seems to be not responsive to the JTAG otherwise.

any help on this is welcome!

X

-

[james_zhang]

Hello Xavier,

All power modes were verified before public release. The symbol cQN_UsePowerDownMode  should not be needed for enabling the low power mode. All power modes should be enabled in the power profiling project. Thanks,

James

[gerardo_rodriguez]

Hello Xavier,

The application note AN01786 is based on a power profiling demo from an older BLE stack which was not released. The power profiling demo which you are testing is from the Beta SDK and has the limitation that applications compiled with MCUXpresso don't support low power modes. You could try using IAR EWARM IDE for testing the power profiling demo.

Regards,