howto reset nrf51422 from reset pin

[Adib]

Hello,

I have a design where nrf51422 works as companion chip together with an other uC as main controller (STM32F4). I need to reset the NRF from the main controller.

I have SDWCLK pulled low by 91kOhm and the SWDIO switched by mosfet down to ground in series to 200Ohm.

Now we encounter that the reset pulse is present but the NRF does not reset.

Here in the forum there where rumor to decrease the resistance of the pulldown on SWDCLK to 470Ohm. We did so.

But still we have no quaranteed reset behavious on all pcbs. Some does, some does not reset.

So what is the recommended RESET cicuit for external reset?

Best regards, Adib.

[Stian Røed Hafskjold]

Are you sure the chip is not in debug mode? In debug mode the NRF_POWER->RESET register has to be set, and the SWDIO must be pulled low for more than 100us.