nrf52 board consuming 16mA when idle

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casouri
 
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nrf52 board consuming 16mA when idle

Post by casouri »

Running the following code consumes 16mA current on my nrf52 board. I guess something other than the nrf52 chip is drawing that current, but I can't figure out what's the problem.

Code: Select all

void setup()
{
  suspendLoop();
}

void loop() {}

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casouri
 
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Re: nrf52 board consuming 16mA when idle

Post by casouri »

I should add that I'm measuring the current by connecting my PC to a usb power meter to the micro usb port on the nrf52 board. Maybe that doesn't give the actual power consumption?

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jevada
 
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Re: nrf52 board consuming 16mA when idle

Post by jevada »

nRF52, as in "nRF52832"? Because that has a CP2102 or something like that on board that takes power. Also, are there any LEDs lit on on the board?
You can probably reduce the total power consumption by removing the CP2102 and enable DCDC by writing the DCDCEN bit: NRF_POWER->DCDCEN = 1;

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casouri
 
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Re: nrf52 board consuming 16mA when idle

Post by casouri »

Yes, nrf52832. I enabled dcdc and it seems to save me 1mA, thanks. Are you saying that if I measure the power consumption through the micro usb port, the port itself consumes some amount of current?

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Re: nrf52 board consuming 16mA when idle

Post by jevada »

casouri wrote:Yes, nrf52832. I enabled dcdc and it seems to save me 1mA, thanks. Are you saying that if I measure the power consumption through the micro usb port, the port itself consumes some amount of current?
The nRF52832 itself does not feature a USB port. The PCB contains a component that acts as a USB port on one side and provides a serial port on the other side. That serial port is connected to the nRF52832. This component is known as a CP2104 (in my previous post I mentioned the CP2102, but it actually is a CP2104). When in operational mode, the CP2104 can consume up to 18.5 mA (!).

Further more, you mention the use of a "USB power meter". These things usually are not the most accurate at low currents (if at all). Do you have more information on that device? Exact type for example?

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casouri
 
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Re: nrf52 board consuming 16mA when idle

Post by casouri »

When in operational mode, the CP2104 can consume up to 18.5 mA (!).
I see that the normal operating current is 17-18mA for this chip, and the non-operating current is 100-200uA. Is it safe to assume that when the usb port is not plugged in, the feather board consumes ~1mA? Is there any way to confirm this without any expensive equipment?
Further more, you mention the use of a "USB power meter". These things usually are not the most accurate at low currents (if at all). Do you have more information on that device? Exact type for example?
The usb power meter I use is this one https://www.makerhawk.com/products/make ... ester-at34 I'm content with anything in the proximity of 1mA, hopefully the resolution of this usb power meter isn't too bad...

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jevada
 
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Re: nrf52 board consuming 16mA when idle

Post by jevada »

I don't think that "power meter" thing is up to the task. A spec like "Current measurement resolution: 0.001A" sounds like accuracy is severely restricted (0.001A = 1 mA). And "Current measurement accuracy: ± (1% + 4 words) @ ​​25 ° C" is a very weird specification (what is a "word" in this case?). I can only assume they mean "4 digit full scale uncertainty" which really doesn't mean a thing without knowing measurement scales.

Abyway, powerconsumption of the nRF52832 peaks at just a tad under 9 mA during advertising (at Vcc = 3V, radio gain cranked up to +4dB), see https://devzone.nordicsemi.com/power/w/ ... uetooth-le. On average, under 100 uA with the "standard" 20ms advertising interval. Increasing the interval to, for example, 250 ms easily halfs that. I can attest that these numbers are pretty close to reality.

Lots of tips to reduce power consumption: https://devzone.nordicsemi.com/nordic/n ... 52-designs (but these may go beyond the normal capabilities the Adafruit runtime environment provide - the platform isn't power optimized!).

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