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Topic: Nano 33 BLE Sense System ON/OFF Minimum Power Consumption (Read 540 times) previous topic - next topic

tangtangdn

Hi,
I would like to push Nano 33 BLE Sense into sleep modes (System ON) to reduce power consumption. I go through some similar or even the same posts in this forum, but it does not reduce to the current level mentioned by the Arduino support.

As the information from Arduino support, it said

Quote
Turn off the sensors:
digitalWrite(PIN_ENABLE_SENSORS_3V3, LOW);

Turn off the I2C pull-up resistors:
digitalWrite(PIN_ENABLE_I2C_PULLUP, LOW);

Cut the 3.3 V jumper on the bottom of the board. This will avoid the power usage of the MPM3610 step-down converter used to convert the 5 V power supply to the 3.3 V supported by the components on the Nano 33 BLE. You will then need to supply power to the board via the 3.3V pin, as it will no longer get power from the USB connection.

Turn off the power LED:
digitalWrite(LED_PWR, LOW);

Use delay() in your sketch when you aren't doing anything to put the nRF52840 to sleep.

Unplug the USB cable and power cycle the board. With that, you will get the power consumption numbers in the tens of microamps on the Nano 33 BLE Sense.

You can also use this code to shut down the processor.                
NRF_POWER->SYSTEMOFF = 1;
However, I cannot achieve tens of microamps at the system ON mode when the board is sleep. It is about 1mA. Please kindly see the details of the method that I measured the current:

I use a DC/DC converter called LM3671 to convert 3.7V to 3.3V. Then, supply the Nano 33 BLE Sense board from 3V3 pin with the 3v3 bridge cutting on the backside. The resistor connected in series in the circuit is 10 Ω. (Please see the attached image 1)


#include <ArduinoBLE.h>
void setup() {
digitalWrite(LED_PWR, LOW);
digitalWrite(PIN_ENABLE_SENSORS_3V3, LOW);
digitalWrite(PIN_ENABLE_I2C_PULLUP, LOW);
}

void loop() {
delay (5000);
}

The voltage of V1 and V2 are measured with the Digilent Analog Discovery 2. It can be seen the voltage of the resistor (V2) is 10mV, which means the current is about 1mA (I have removed the USB cable and repowered the board from 3V3 pin). (Please see the attached image 2)


After adding NRF_POWER->SYSTEMOFF = 1, the voltage of the resistor (V2) is reduced to about 1mV, which means the current is about 100 uA. (Please see the attached image 3)


I also tried to switch PIN_ENABLE_SENSORS_3V3 and PIN_ENABLE_I2C_PULLUP in the pins_arduino.h file, but it has no significant effect.

Could anyone kindly help to see whether my measurement method has problems? Or this is the minimum power consumption of this Nano 33 BLE Sense board?

Thank you so much in advance.

Kind regards,
Tang

kbaggen

Hi, not sure I understand it all, but I have brought 3 , and had to return 2. But meerly all have had some issues, see below.

One had broken attenna, 
other one smoked at attaching usb power, 
the 3rd even working did not show the yellow light at bootloader (did not brother to send back), 
and as of today I fund out that the last one I played with do never get lower than 20 mAh even in 3.3v cut mode and all the coding to reduce power it should get way lower. 
Hence, out of 5, only one seems to be working as it should?!??!

My code hold in avange 1.6 mAh, and seems working fine for those 2 there is now working.


Hence, they seem to me to be very faulty, and you might have one there never really go low in power.

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