Increase sleep current after implementing a workaround for nrf52832 errata 220

[pd@learner]

Hi,

I have a custom board using nrf 52832. I am using SDK 15.2.0 and softdevice s132 v6.1.0.

I have referred following link

https://devzone.nordicsemi.com/f/nordic-q-a/58652/additional-questions-to-nrf52832-errata-220-clearification.

Also referred nRF52 Series > nRF52832 > Errata > nRF52832 Revision 2 Errata > New and inherited anomalies.

By using the above link I am trying to implement a workaround for errata 220.

I have written a simple application that reads battery status after every 60 sec and transmitted it in mfg data. I have made changes in the nrf_pwr_mgmt_run function as below.

void nrf_pwr_mgmt_run(void)
{
    PWR_MGMT_FPU_SLEEP_PREPARE();
    PWR_MGMT_SLEEP_LOCK_ACQUIRE();
    PWR_MGMT_CPU_USAGE_MONITOR_SECTION_ENTER();
    PWR_MGMT_DEBUG_PIN_SET();

    // Wait for an event.
#ifdef SOFTDEVICE_PRESENT
    if (nrf_sdh_is_enabled())
    {
			// commented by prashant test purpose 10082020
				
//        ret_code_t ret_code = sd_app_evt_wait();
//        ASSERT((ret_code == NRF_SUCCESS) || (ret_code == NRF_ERROR_SOFTDEVICE_NOT_ENABLED));
//        UNUSED_VARIABLE(ret_code);
//			
			// added by prashant for test purpose
			SCB->SCR |= SCB_SCR_SEVONPEND_Msk;
			__disable_irq();
			__WFE();
			__nop();__nop();__nop();__nop();
			__enable_irq();
			
			////////////////////////////////////////////
						
    }
    else
#endif // SOFTDEVICE_PRESENT
    {
        // Wait for an event.
			  __WFE();										
		  // Clear the internal event register.
        __SEV();
				__WFE();										
			
    }

    PWR_MGMT_DEBUG_PIN_CLEAR();
    PWR_MGMT_CPU_USAGE_MONITOR_SECTION_EXIT();
    PWR_MGMT_SLEEP_LOCK_RELEASE();
}

But After implementing the above code sleep current increases. kindly find below images for sleep current with and without a workaround implementation.

a) Without Workaround implementation.

b) With Workaround implementation.

[Vidar Berg]

Hello,

I suspect the increased current may be related to the following errata: [75] MWU: Increased current consumption. This workaround is normally taken care of by the sd_app_evt_wait() function. Please try to disable the MWU prior to entering idle and see if it helps.

[pd@learner]

I am using softdevice s132 v6.1.0.  

I have used sd_app_evt_wait function to put a device in sleep mode.

Is it necessary to apply this workaround( errata 220 and 75 ) in our code?

[Vidar Berg]

It is necessary if you need to eliminate this risk. But my experience is that the errata 220 issue is very rare and that it can't be triggered with just any BLE application. As you can see from the errata description, the condition for this to occur is a specific sequence of very accurately timed events. 

Missing the first write on wake-up will likely lead to a fault exception.