nRF52840 UARTE+GPIOTE current consumption as compared to nRF52832

RE: nRF52840 UARTE+GPIOTE current consumption as compared to nRF52832

Einar Thorsrud — Wed, 17 Apr 2019 07:24:34 GMT

Hi,

I am sorry, I read your initial question too quickly, so I did not noise that you intended to test with the UART active. These numbers make sense. The UARTE peripheral has a higher current consumption than the UART peripheral, due to the added current consumption of the DMA bus. (This is the same for all peripherals where you have DMA and non-DMA alternatives, due to the DMA logic.)

There is no way to bring down this current consumption specifically, other than making sure that you enable the DC/DC. You should also make sure that you only enable peripherals when they are needed, and disable them immediately after, so that you reduce the average current consumption.

RE: nRF52840 UARTE+GPIOTE current consumption as compared to nRF52832

catsunami — Tue, 16 Apr 2019 22:04:08 GMT

Hi Einar, as stated in my post, I am using the UART peripheral. Below is a sample main function that I am using. Here, with UART I am getting about 0.8mA. Is this expected? With UARTE I see about 1.2mA. Is there any way to bring this current down?

I am testing on the nRF52840 DK, and using a 50kHz Keysight DMM to measure (so I'm sure it's accurate enough for this purpose).

int main()
{
   {NRF_UART0->ENABLE = UART_ENABLE_ENABLE_Disabled << UART_ENABLE_ENABLE_Pos; \
                        *(volatile uint32_t *)0x40002FFC = 0; \
                        *(volatile uint32_t *)0x40002FFC; \
                        *(volatile uint32_t *)0x40002FFC = 1;}
    
   NRF_P0->DIRSET = 0xFFFFFFFC;
   NRF_P0->OUTCLR = 0xFFFFFFFC;
   NRF_P1->DIRSET = 0xFFFFFFFF;
   NRF_P1->OUTCLR = 0xFFFFFFFF;
  
   NRF_CLOCK->TASKS_HFCLKSTART = 1;
   while(NRF_CLOCK->EVENTS_HFCLKSTARTED == 0)
   {
   
   }
   NRF_CLOCK->EVENTS_HFCLKSTARTED = 0;
   NRF_UART0->ENABLE = UART_ENABLE_ENABLE_Enabled << UART_ENABLE_ENABLE_Pos;
   
   
   NRF_UART0->TASKS_STARTRX = 1;
    
   NRF_POWER->DCDCEN = POWER_DCDCEN_DCDCEN_Disabled << POWER_DCDCEN_DCDCEN_Pos;
   NRF_POWER->DCDCEN0 = POWER_DCDCEN0_DCDCEN_Disabled << POWER_DCDCEN0_DCDCEN_Pos;
   
   for (uint32_t i = 0; i < 5000000; i++)
   {
      __NOP();
   }
   
   while(1)
   {
      __WFE();
      //__SEV();
      //__WFE();
   }
}

RE: nRF52840 UARTE+GPIOTE current consumption as compared to nRF52832

Einar Thorsrud — Mon, 15 Apr 2019 12:46:07 GMT

Hi,

It is difficult to say without knowing more about your app and HW, which peripherals etc. are active. Generally you should only get about 2-3 μA in low power mode (calling sd_app_evt_wait()) provided you are not using any additional resources at that time.