nRF9160 System Off Mode Bus Fault Error

Question

Hey, 
 
 I'm trying to put the nRF9160 into System Off mode and am getting a bus fault error when writing to the REGULATORS module. This is the error output: 
 
 ***** BUS FAULT ***** Precise data bus error BFAR Address: 0x40004500 ***** Hardware exception ***** Current thread ID = 0x200245f8 Faulting instruction address = 0x412da Fatal fault in thread 0x200245f8! Aborting. 
 
 I first set the modem to power off using ```lte_power_off()```, and then call ```nrf_regulators_system_off(NRF_REGULATORS_NS);``` 
 
 I'm calling this from a non-secure app. Do I have to add configuration in the bootloader to allow non-secure access to the REGULATORS registers? Are there additional steps to configure before going into System Off mode? 
 
 - Jack

Martin Lesund · Answer

Hi Jack, Sorry for my confusion. 
 
 Basically we need to set the regulators in non-secure to be able to use it: 
 To set the Regulators in non-secure we can add this in the spm.c : 
 PERIPH("NRF_REGULATORS", NRF_REGULATORS_S, CONFIG_SPM_NRF_REGULATORS_NS), 
 And we need to set it as default non-secure in the Kconfig file: 
 config SPM_NRF_REGULATORS_NS
	bool "Regulators is Non-Secure"
	default y 
 
 From the serial output you can confirm that the Regulators are set in Non-Secure: 
 
 Best Regards, 
 Martin L.