Sample code for 2.2uA current draw test

[anupamvarghese]

For our custom nrf9151 board,

The following is the prj.conf:

CONFIG_SERIAL=n
CONFIG_UART_CONSOLE=n
CONFIG_LOG=n
CONFIG_LOG_BACKEND_RTT=n
CONFIG_LOG_BACKEND_UART=n

CONFIG_NRF_MODEM_LIB=n 
CONFIG_NETWORKING=n 
CONFIG_I2C=n
CONFIG_ADC=n
CONFIG_CBPRINTF_FP_SUPPORT=n
CONFIG_INPUT=n
CONFIG_PWM=n
CONFIG_PWM_NRFX=n

CONFIG_NVS=n
CONFIG_FLASH=n

There are no pullups on any GPIO and for now, assume there are no peripherals connected,

but there is a flash chip W25Q32JVZPIQ with the following pinout:

WP: 11
DI: 10
CLK: 9
RST: 8
DO:12
CS: 13

The following is called in main:

static const struct device *const port0 = DEVICE_DT_GET(DT_NODELABEL(gpio0));


ret = gpio_pin_configure(port0, 0, GPIO_OUTPUT_LOW );
ret = gpio_pin_configure(port0, 1, GPIO_OUTPUT_LOW );
ret = gpio_pin_configure(port0, 2, GPIO_OUTPUT_LOW );
ret = gpio_pin_configure(port0, 3, GPIO_OUTPUT_LOW );
ret = gpio_pin_configure(port0, 4, GPIO_OUTPUT_LOW );
ret = gpio_pin_configure(port0, 5, GPIO_OUTPUT_LOW );

ret = gpio_pin_configure(port0, 6, GPIO_OUTPUT_LOW );
ret = gpio_pin_configure(port0, 7, GPIO_OUTPUT_LOW );

ret = gpio_pin_configure(port0, 8, GPIO_OUTPUT_LOW );
ret = gpio_pin_configure(port0, 9, GPIO_OUTPUT_LOW );
ret = gpio_pin_configure(port0, 10, GPIO_OUTPUT_LOW );
ret = gpio_pin_configure(port0, 11, GPIO_OUTPUT_LOW );
ret = gpio_pin_configure(port0, 12, GPIO_OUTPUT_LOW );

ret = gpio_pin_configure(port0, 13, GPIO_OUTPUT_LOW );

ret = gpio_pin_configure(port0, 14, GPIO_OUTPUT_LOW );
ret = gpio_pin_configure(port0, 15, GPIO_OUTPUT_LOW );
ret = gpio_pin_configure(port0, 16, GPIO_OUTPUT_LOW );

ret = gpio_pin_configure(port0, 17, GPIO_OUTPUT_LOW );
ret = gpio_pin_configure(port0, 18, GPIO_OUTPUT_LOW );
ret = gpio_pin_configure(port0, 19, GPIO_OUTPUT_LOW );
ret = gpio_pin_configure(port0, 20, GPIO_OUTPUT_LOW );	

ret = gpio_pin_configure(port0, 21, GPIO_OUTPUT_LOW );


ret = gpio_pin_configure(port0, 22, GPIO_OUTPUT_LOW );
ret = gpio_pin_configure(port0, 23, GPIO_OUTPUT_LOW );
ret = gpio_pin_configure(port0, 24, GPIO_OUTPUT_LOW );
ret = gpio_pin_configure(port0, 25, GPIO_OUTPUT_LOW );

ret = gpio_pin_configure(port0, 26, GPIO_OUTPUT_LOW );
ret = gpio_pin_configure(port0, 27, GPIO_OUTPUT_LOW );

ret = gpio_pin_configure(port0, 29, GPIO_OUTPUT_LOW );

ret = gpio_pin_configure(port0, 30, GPIO_OUTPUT_LOW );
ret = gpio_pin_configure(port0, 31, GPIO_OUTPUT_LOW );

NRF_REGULATORS->SYSTEMOFF = 1;

Essentially, all pins are pulled LOW and SYSTEM_OFF is invoked.

For some strange reason, I can see a current draw of 3.5mA !


What am I missing?
How do I test a low power scenario for my board?


How do I reach 2.2uA?

IMCUON1 | MCU on IDLE, modem off, RTC on | 2.2 µA

as described in: 
https://docs.nordicsemi.com/bundle/ps_nrf9151/page/_tmp/alta.nRF9151/autodita/APPLICATION.CURRENT/parameters.id_current_sleep.html

[Håkon Alseth]

Shall all your pins be output and set to low? You have to check your design to see if this is indeed the correct idle level.

Kind regards,

Håkon

[anupamvarghese]

Thanks for that tip!
The W25Q32JVZPIQ has CS active LOW.
Set that to high and now I am seeing 7.2uA. Which is great, but I seem to be still missing something.

Other than that
pin 28 -- buzzer -- gnd
pin 05 -- switch -- gnd
pin 04 -- led -- gnd
pin 15, 21, 48,  -- EN_PIN for 3 x SIP32431DR3-T1GE3 load switch (active HIGH, should have nA quiescent)
pin 27 -- UART Tx (not connected)
pin 26 -- UART Rx (not connected)

[Håkon Alseth]

Hi,

 

anupamvarghese said:

now I am seeing 7.2uA. Which is great, but I seem to be still missing something.

You need to check the datasheet of your external components, and add the sleep currents of those.

A flash usually draws up to 10 uA, depending on the sleep mode its in.

 

Kind regards,

Håkon