How to put the system in off mode nrf51822

[SumitS]

Hello,

I want to measure the current in system off mode. I am flashing the S110 softdevice and bootloader in the nrf51822 chip. Using BLE i am flashing an application code which does nothing but calls the function sd_power_system_off(). When we measure the current the it is about 1mA. We are using the Insight SIP evaluation kit. Also after flashing the code we restarted the system and removed the debugger.

Could you please guide us as to where we are wrong.

Thanks & Regards, Sumit Singhal

[SumitS]

i tried using pul up and pull down configuartion. But it still takes same amount of current. I am using a Insight SIP evaluation kit.

[Susheel Nuguru]

I am not so familiar with this evaluation kit, but are there any LED's on? i see that you do some pin clear, but on some devkits here the latches are inverted and the pin clear would light a LED.

Another thing is that you can try to flash your app without softdevice and bootloader (clear the chip and flash your app to ROM address 0). Then make measurements and see if the current consumption drops. We can then isolate the softdevice and bootloader from this.

[Susheel Nuguru]

I am not sure if this will work but worth a shot. Can you add this line just before going to system off

NRF_POWER->TASKS_LOWPWR = 1;

explanation is here

[SumitS]

Added this line. But it still draws the same current.

Also when i dont flash the S110 softdevice and bootloader it takes about 2.5mA current.

[Susheel Nuguru]

OK, then we can remove softdevice and bootloader from the picture And the code with pull settings changed looks good too. To make sure that your board is in system off, check if it gets reset when it you press the wakeup button. If there is reset, then the wake of from system off worked, else the chip might not have gone in system off mode at all. Otherwise it should be something with the board. My guess is that there is some leakage somewhere. Check with the board schematics to see if it is following our reference designs. I would recommend you to contact the company who made this custom boards.